1X11VNC(1) User Commands X11VNC(1)
2
6 x11vnc - allow VNC connections to real X11 displays
7 version: 0.9.14, lastmod: 2013-11-21
8
10 x11vnc [OPTION]...
11
13 Typical usage is:
14 Run this command in a shell on the remote machine "far-host"
16 with X session you wish to view:
17 x11vnc -display :0
19 Then run this in another window on the machine you are sitting
21 at:
22 vncviewer far-host:0
24 Once x11vnc establishes connections with the X11 server and starts lis‐
26 tening as a VNC server it will print out a string: PORT=XXXX where XXXX
27 is typically 5900 (the default VNC server port). One would next run
28 something like this on the local machine: "vncviewer hostname:N" where
29 "hostname" is the name of the machine running x11vnc and N is XXXX -
30 5900, i.e. usually "vncviewer hostname:0".
31 By default x11vnc will not allow the screen to be shared and it will
33 exit as soon as the client disconnects. See -shared and -forever below
34 to override these protections. See the FAQ for details how to tunnel
35 the VNC connection through an encrypted channel such as ssh(1). In
36 brief:
37 ssh -t -L 5900:localhost:5900 far-host 'x11vnc -localhost -dis‐
39 play :0'
40 % vncviewer -encodings 'copyrect tight zrle hextile' localhost:0
42 Also, use of a VNC password (-rfbauth or -passwdfile) is strongly rec‐
44 ommended.
45 For additional info see: http://www.karlrunge.com/x11vnc/ and
47 http://www.karlrunge.com/x11vnc/faq.html
48 Config file support: if the file $HOME/.x11vncrc exists then each line
50 in it is treated as a single command line option. Disable with -norc.
51 For each option name, the leading character "-" is not required. E.g.
52 a line that is either "forever" or "-forever" may be used and are
53 equivalent. Likewise "wait 100" or "-wait 100" are acceptable and
54 equivalent lines. The "#" character comments out to the end of the
55 line in the usual way (backslash it for a literal). Leading and trail‐
56 ing whitespace is trimmed off. Lines may be continued with a "\" as
57 the last character of a line (it becomes a space character).
58
60 -display disp
61 X11 server display to connect to, usually :0. The X server
63 process must be running on same machine and support MIT-SHM.
64 Equivalent to setting the DISPLAY environment variable to disp.
65 See the description below of the "-display WAIT:..." exten‐
67 sions, where alias "-find" will find the user's display automat‐
68 ically, and "-create" will create a Xvfb session if no session
69 is found.
70 -auth file
72 Set the X authority file to be file, equivalent to setting the
74 XAUTHORITY environment variable to file before startup. Same as
75 -xauth file. See Xsecurity(7) , xauth(1) man pages for more
76 info.
77 Use '-auth guess' to have x11vnc use its -findauth mechanism
79 (described below) to try to guess the XAUTHORITY filename and
80 use it.
81 XDM/GDM/KDM: if you are running x11vnc as root and want to find
83 the XAUTHORITY before anyone has logged into an X session yet,
84 use: x11vnc -env FD_XDM=1 -auth guess ... (This will also find
85 the XAUTHORITY if a user is already logged into the X session.)
86 When running as root, FD_XDM=1 will be tried if the initial
87 -auth guess fails.
88 -N
90 If the X display is :N, try to set the VNC display to also be :N
92 This just sets the -rfbport option to 5900+N The program will
93 exit immediately if that port is not available. The -N option
94 only works with normal -display usage, e.g. :0 or :8, -N is
95 ignored in the -display WAIT:..., -create, -find, -svc, -redi‐
96 rect, etc modes.
97 -autoport n
99 Automatically probe for a free VNC port starting at n. The
101 default is to start probing at 5900. Use this to stay away from
102 other VNC servers near 5900.
103 -rfbport str
105 The VNC port to listen on (a LibVNCServer option), e.g. 5900,
107 5901, etc. If specified as "-rfbport PROMPT" then the x11vnc
108 -gui is used to prompt the user to enter the port number.
109 -6
111 IPv6 listening support. In addition to IPv4, the IPv6 address
113 is listened on for incoming connections. The same port number
114 as IPv4 is used.
115 NOTE: This x11vnc binary was compiled to have the "-6" IPv6
117 listening mode ENABLED by default (CPPFLAGS -DX11VNC_LISTEN6=1).
118 So to disable IPv6 listening mode you MUST supply the "-no6"
119 option (see below.)
120 The "-6" mode works for both normal connections and -ssl
122 encrypted ones. Nearly everything is supported for the IPv6
123 case, but there are a few exceptions. See -stunnel for its IPv6
124 support.
125 Currently, for absolutely everything to work correctly the
127 machine may need to have some IPv4 support, at the least for the
128 loopback interface. However, for nearly all usage modes no IPv4
129 support is required. See -nopiv4.
130 If you have trouble compiling or running in IPv6 mode, set
132 -DX11VNC_IPV6=0 in CPPFLAGS when configuring to disable IPv6
133 support.
134 -no6
136 Disable IPv6 listening support (only useful if the "-6" mode is
138 compiled in to be the default; see the X11VNC_LISTEN6 descrip‐
139 tion above under "-6".)
140 -noipv6
142 Do not try to use IPv6 for any listening or connecting sockets.
144 This includes both the listening service port(s) and outgoing
145 connections from -connect, -connect_or_exit, or -proxy. Use
146 this if you are having problems due to IPv6.
147 -noipv4
149 Do not try to use IPv4 for any listening or connecting sockets.
151 This is mainly for exploring the behavior of x11vnc on an
152 IPv6-only system, but may have other uses.
153 -reopen
155 If the X server connection is disconnected, try to reopen the X
157 display (up to one time.) This is of use for display managers
158 like GDM (KillInitClients option) that kill x11vnc just after
159 the user logs into the X session. Note: the reopened state may
160 be unstable. Set X11VNC_REOPEN_DISPLAY=n to reopen n times and
161 set X11VNC_REOPEN_SLEEP_MAX to the number of seconds, default
162 10, to keep trying to reopen the display (once per second.)
163 Update: as of 0.9.9, x11vnc tries to automatically avoid being
165 killed by the display manager by delaying creating windows or
166 using XFIXES. So you shouldn't need to use KillInit‐
167 Clients=false as long as you log in quickly enough (within 45
168 seconds of connecting.) You can disable this by setting
169 X11VNC_AVOID_WINDOWS=never. You can also set it to the number
170 of seconds to delay.
171 -reflect host:N
173 Instead of connecting to and polling an X display, connect to
175 the remote VNC server host:N and be a reflector/repeater for it.
176 This is useful for trying to manage the case of many simultane‐
177 ous VNC viewers (e.g. classroom broadcasting) where, e.g. you
178 put a repeater on each network switch, etc, to improve perfor‐
179 mance by distributing the load and network traffic. Implies
180 -shared (use -noshared as a later option to disable). See the
181 discussion below under -rawfb vnc:host:N for more details.
182 -id windowid
184 Show the X window corresponding to windowid not the entire dis‐
186 play. New windows like popup menus, transient toplevels, etc,
187 may not be seen or may be clipped. Disabling SaveUnders or
188 BackingStore in the X server may help show them. x11vnc may
189 crash if the window is initially partially obscured, changes
190 size, is iconified, etc. Some steps are taken to avoid this and
191 the -xrandr mechanism is used to track resizes. Use xwininfo(1)
192 to get the window id, or use "-id pick" to have x11vnc run xwin‐
193 info(1) for you and extract the id. The -id option is useful
194 for exporting very simple applications (e.g. the current view on
195 a webcam).
196 -sid windowid
198 As -id, but instead of using the window directly it shifts a
200 root view to it: this shows SaveUnders menus, etc, although they
201 will be clipped if they extend beyond the window.
202 -tag str
204 This option is ignored, but allows you to specify a unique
206 string on the x11vnc command line, for example "-tag
207 test34934z", this could enable a reliable way to identify dif‐
208 ferent x11vnc processes via their command lines (see ps(1) ,
209 pgrep(1) , and pkill(1) and /proc/PID/cmdline.)
210 -appshare
212 Simple application sharing based on the -id/-sid mechanism.
214 Every new toplevel window that the application creates induces a
215 new viewer window via a reverse connection. The -id/-sid and
216 -connect options are required. Run 'x11vnc -appshare -help' for
217 more info.
218 -clip WxH+X+Y
220 Only show the sub-region of the full display that corresponds to
222 the rectangle geometry with size WxH and offset +X+Y. The VNC
223 display has size WxH (i.e. smaller than the full display). This
224 also works for -id/-sid mode where the offset is relative to the
225 upper left corner of the selected window. An example use of
226 this option would be to split a large (e.g. Xinerama) display
227 into two parts to be accessed via separate viewers by running a
228 separate x11vnc on each part.
229 Use '-clip xinerama0' to clip to the first xinerama sub-screen
231 (if xinerama is active). xinerama1 for the 2nd sub-screen, etc.
232 This way you don't need to figure out the WxH+X+Y of the desired
233 xinerama sub-screen. screens are sorted in increasing distance
234 from the (0,0) origin (I.e. not the Xserver's order).
235 -flashcmap
237 In 8bpp indexed color, let the installed colormap flash as the
239 pointer moves from window to window (slow). Also try the -8to24
240 option to avoid flash altogether.
241 -shiftcmap n
243 Rare problem, but some 8bpp displays use less than 256 color‐
245 cells (e.g. 16-color grayscale, perhaps the other bits are used
246 for double buffering) *and* also need to shift the pixels values
247 away from 0, .., ncells. n indicates the shift to be applied to
248 the pixel values. To see the pixel values set DEBUG_CMAP=1 to
249 print out a colormap histogram. Example: -shiftcmap 240
250 -notruecolor
252 For 8bpp displays, force indexed color (i.e. a colormap) even if
254 it looks like 8bpp TrueColor (rare problem).
255 -advertise_truecolor
257 If the X11 display is indexed color, lie to clients when they
259 first connect by telling them it is truecolor. To workaround
260 RealVNC: inPF has colourMap but not 8bpp Use '-advertise_true‐
261 color reset' to reset client fb too.
262 -visual n
264 This option probably does not do what you think. It simply
266 *forces* the visual used for the framebuffer; this may be a bad
267 thing... (e.g. messes up colors or cause a crash). It is useful
268 for testing and for some workarounds. n may be a decimal num‐
269 ber, or 0x hex. Run xdpyinfo(1) for the values. One may also
270 use "TrueColor", etc. see <X11/X.h> for a list. If the string
271 ends in ":m" then for better or for worse the visual depth is
272 forced to be m. You may want to use -noshm when using this
273 option (so XGetImage may automatically translate the pixel
274 data).
275 -overlay
277 Handle multiple depth visuals on one screen, e.g. 8+24 and 24+8
279 overlay visuals (the 32 bits per pixel are packed with 8 for
280 PseudoColor and 24 for TrueColor).
281 Currently -overlay only works on Solaris via XReadScreen(3X11)
283 and IRIX using XReadDisplay(3). On Solaris there is a problem
284 with image "bleeding" around transient popup menus (but not for
285 the menu itself): a workaround is to disable SaveUnders by pass‐
286 ing the "-su" argument to Xsun (in /etc/dt/config/Xservers).
287 Use -overlay as a workaround for situations like these: Some
289 legacy applications require the default visual to be 8bpp
290 (8+24), or they will use 8bpp PseudoColor even when the default
291 visual is depth 24 TrueColor (24+8). In these cases colors in
292 some windows will be incorrect in x11vnc unless -overlay is
293 used. Another use of -overlay is to enable showing the exact
294 mouse cursor shape (details below).
295 Under -overlay, performance will be somewhat slower due to the
297 extra image transformations required. For optimal performance
298 do not use -overlay, but rather configure the X server so that
299 the default visual is depth 24 TrueColor and try to have all
300 apps use that visual (e.g. some apps have -use24 or -visual
301 options).
302 -overlay_nocursor
304 Sets -overlay, but does not try to draw the exact mouse cursor
306 shape using the overlay mechanism.
307 -8to24 [opts]
309 Try this option if -overlay is not supported on your OS, and you
311 have a legacy 8bpp app that you want to view on a multi-depth
312 display with default depth 24 (and is 32 bpp) OR have a default
313 depth 8 display with depth 24 overlay windows for some apps.
314 This option may not work on all X servers and hardware (tested
315 on XFree86/Xorg mga driver and Xsun). The "opts" string is not
316 required and is described below.
317 This mode enables a hack where x11vnc monitors windows within 3
319 levels from the root window. If it finds any that are 8bpp it
320 extracts the indexed color pixel values using XGetImage() and
321 then applies a transformation using the colormap(s) to create
322 TrueColor RGB values that it in turn inserts into bits 1-24 of
323 the framebuffer. This creates a depth 24 "view" of the display
324 that is then exported via VNC.
325 Conversely, for default depth 8 displays, the depth 24 regions
327 are read by XGetImage() and everything is transformed and
328 inserted into a depth 24 TrueColor framebuffer.
329 Note that even if there are *no* depth 24 visuals or windows
331 (i.e. pure 8bpp), this mode is potentially an improvement over
332 -flashcmap because it avoids the flashing and shows each window
333 in the correct color.
334 This method works OK, but may still have bugs and it does hog
336 resources. If there are multiple 8bpp windows using different
337 colormaps, one may have to iconify all but one for the colors to
338 be correct.
339 There may be painting errors for clipping and switching between
341 windows of depths 8 and 24. Heuristics are applied to try to
342 minimize the painting errors. One can also press 3 Alt_L's in a
343 row to refresh the screen if the error does not repair itself.
344 Also the option -fixscreen 8=3.0 or -fixscreen V=3.0 may be used
345 to periodically refresh the screen at the cost of bandwidth
346 (every 3 sec for this example).
347 The [opts] string can contain the following settings. Multiple
349 settings are separated by commas.
350 For for some X servers with default depth 24 a speedup may be
352 achieved via the option "nogetimage". This enables a scheme
353 were XGetImage() is not used to retrieve the 8bpp data.
354 Instead, it assumes that the 8bpp data is in bits 25-32 of the
355 32bit X pixels. There is no requirement that the X server
356 should put the data there for our poll requests, but some do and
357 so the extra steps to retrieve it can be skipped. Tested with
358 mga driver with XFree86/Xorg. For the default depth 8 case this
359 option is ignored.
360 To adjust how often XGetImage() is used to poll the non-default
362 visual regions for changes, use the option "poll=t" where "t" is
363 a floating point time. (default: 0.05)
364 Setting the option "level2" will limit the search for non-
366 default visual windows to two levels from the root window. Do
367 this on slow machines where you know the window manager only
368 imposes one extra window between the app window and the root
369 window.
370 Also for very slow machines use "cachewin=t" where t is a float‐
372 ing point amount of time to cache XGetWindowAttributes results.
373 E.g. cachewin=5.0. This may lead to the windows being unnoticed
374 for this amount of time when deiconifying, painting errors, etc.
375 While testing on a very old SS20 these options gave tolerable
377 response: -8to24 poll=0.2,cachewin=5.0. For this machine -over‐
378 lay is supported and gives better response.
379 Debugging for this mode can be enabled by setting "dbg=1",
381 "dbg=2", or "dbg=3".
382 -24to32
384 Very rare problem: if the framebuffer (X display or -rawfb) is
386 24bpp instead of the usual 32bpp, then dynamically transform the
387 pixels to 32bpp. This will be slower, but can be used to work
388 around problems where VNC viewers cannot handle 24bpp (e.g.
389 "main: setPF: not 8, 16 or 32 bpp?"). See the FAQ for more
390 info.
391 In the case of -rawfb mode, the pixels are directly modified by
393 inserting a 0 byte to pad them out to 32bpp. For X displays, a
394 kludge is done that is equivalent to "-noshm -visual True‐
395 Color:32". (If better performance is needed for the latter,
396 feel free to ask).
397 -scale fraction
399 Scale the framebuffer by factor fraction. Values less than 1
401 shrink the fb, larger ones expand it. Note: the image may not be
402 sharp and response may be slower. If fraction contains a deci‐
403 mal point "." it is taken as a floating point number, alterna‐
404 tively the notation "m/n" may be used to denote fractions
405 exactly, e.g. -scale 2/3
406 To scale asymmetrically in the horizontal and vertical direc‐
408 tions, specify a WxH geometry to stretch to: e.g. '-scale
409 1024x768', or also '-scale 0.9x0.75'
410 Scaling Options: can be added after fraction via ":", to supply
412 multiple ":" options use commas. If you just want a quick,
413 rough scaling without blending, append ":nb" to fraction (e.g.
414 -scale 1/3:nb). No blending is the default for 8bpp indexed
415 color, to force blending for this case use ":fb".
416 To disable -scrollcopyrect and -wirecopyrect under -scale use
418 ":nocr". If you need to to enable them use ":cr" or specify
419 them explicitly on the command line. If a slow link is
420 detected, ":nocr" may be applied automatically. Default: :cr
421 More esoteric options: for compatibility with vncviewers the
423 scaled width is adjusted to be a multiple of 4: to disable this
424 use ":n4". ":in" use interpolation scheme even when shrinking,
425 ":pad" pad scaled width and height to be multiples of scaling
426 denominator (e.g. 3 for 2/3).
427 -geometry WxH
429 Same as -scale WxH
431 -scale_cursor frac
433 By default if -scale is supplied the cursor shape is scaled by
435 the same factor. Depending on your usage, you may want to scale
436 the cursor independently of the screen or not at all. If you
437 specify -scale_cursor the cursor will be scaled by that factor.
438 When using -scale mode to keep the cursor at its "natural" size
439 use "-scale_cursor 1". Most of the ":" scaling options apply
440 here as well.
441 -viewonly
443 All VNC clients can only watch (default off).
445 -shared
447 VNC display is shared, i.e. more than one viewer can connect at
449 the same time (default off).
450 -once
452 Exit after the first successfully connected viewer disconnects,
454 opposite of -forever. This is the Default.
455 -forever
457 Keep listening for more connections rather than exiting as soon
459 as the first client(s) disconnect. Same as -many
460 To get the standard non-shared VNC behavior where when a new VNC
462 client connects the existing VNC client is dropped use: -never‐
463 shared -forever This method can also be used to guard against
464 hung TCP connections that do not go away.
465 -loop
467 Create an outer loop restarting the x11vnc process whenever it
469 terminates. -bg and -inetd are ignored in this mode (however
470 see -loopbg below).
471 Useful for continuing even if the X server terminates and
473 restarts (at that moment the process will need permission to
474 reconnect to the new X server of course).
475 Use, e.g., -loop100 to sleep 100 millisecs between restarts,
477 etc. Default is 2000ms (i.e. 2 secs) Use, e.g. -loop300,5 to
478 sleep 300 ms and only loop 5 times.
479 If -loopbg (plus any numbers) is specified instead, the "-bg"
481 option is implied and the mode approximates inetd(8) usage to
482 some degree. In this case when it goes into the background any
483 listening sockets (i.e. ports 5900, 5800) are closed, so the
484 next one in the loop can use them. This mode will only be of
485 use if a VNC client (the only client for that process) is
486 already connected before the process goes into the background,
487 for example, usage of -display WAIT:.., -svc, and -connect can
488 make use of this "poor man's" inetd mode. The default wait time
489 is 500ms in this mode. This usage could use useful: -svc -bg
490 -loopbg
491 -timeout n
493 Exit unless a client connects within the first n seconds after
495 startup.
496 If there have been no connection attempts after n seconds x11vnc
498 exits immediately. If a client is trying to connect but has not
499 progressed to the normal operating state, x11vnc gives it a few
500 more seconds to finish and exits if it does not make it to the
501 normal state.
502 For reverse connections via -connect or -connect_or_exit a time‐
504 out of n seconds will be set for all reverse connects. If the
505 connect timeout alarm goes off, x11vnc will exit immediately.
506 -sleepin n
508 At startup sleep n seconds before proceeding (e.g. to allow
510 redirs and listening clients to start up)
511 If a range is given: '-sleepin min-max', a random value between
513 min and max is slept. E.g. '-sleepin 0-20' and ´-sleepin 10-30'.
514 Floats are allowed too.
515 -inetd
517 Launched by inetd(8): stdio instead of listening socket. Note:
519 if you are not redirecting stderr to a log file (via shell 2> or
520 -o option) you MUST also specify the -q option, otherwise the
521 stderr goes to the viewer which will cause it to abort. Speci‐
522 fying both -inetd and -q and no -o will automatically close the
523 stderr.
524 If the libvncserver used supports non AF_INET sockets (the one
526 bundled in x11vnc 0.9.13 and later does), then -inetd mode can
527 be used for a raw stdio pipe. For example, using the SSVNC
528 viewer exec=... mechanism:
529 ssvnc -viewer exec="ssh -tt -e none user@host \ ´x11vnc -inetd
531 -o log.txt -display :0'"
532 where the long cmdline has been split. In the above the only
534 TCP connection is that of the ssh connection. There is no port
535 redirection (-L), etc.; raw stdio is used on both sides of the
536 ssh. In some cases the -tt option is not needed.
537 -tightfilexfer
539 Enable the TightVNC file transfer extension. Note that that when
541 the -viewonly option is supplied all file transfers are dis‐
542 abled. Also clients that log in viewonly cannot transfer files.
543 However, if the remote control mechanism is used to change the
544 global or per-client viewonly state the filetransfer permissions
545 will NOT change.
546 IMPORTANT: please understand if -tightfilexfer is specified and
548 you run x11vnc as root for, say, inetd or display manager (gdm,
549 kdm, ...) access and you do not have it switch users via the
550 -users option, then VNC Viewers that connect are able to do
551 filetransfer reads and writes as *root*.
552 Also, tightfilexfer is disabled in -unixpw mode.
554 -ultrafilexfer
556 Note: to enable UltraVNC filetransfer and to get it to work you
558 probably need to supply these LibVNCServer options: "-rfbversion
559 3.6 -permitfiletransfer" "-ultrafilexfer" is an alias for this
560 combination.
561 IMPORTANT: please understand if -ultrafilexfer is specified and
563 you run x11vnc as root for, say, inetd or display manager (gdm,
564 kdm, ...) access and you do not have it switch users via the
565 -users option, then VNC Viewers that connect are able to do
566 filetransfer reads and writes as *root*.
567 Note that sadly you cannot do both -tightfilexfer and -ultra‐
569 filexfer at the same time because the latter requires setting
570 the version to 3.6 and tightvnc will not do filetransfer when it
571 sees that version number.
572 -http
574 Instead of using -httpdir (see below) to specify where the Java
576 vncviewer applet is, have x11vnc try to *guess* where the direc‐
577 tory is by looking relative to the program location and in stan‐
578 dard locations (/usr/local/share/x11vnc/classes, etc). Under
579 -ssl or -stunnel the ssl classes subdirectory is sought.
580 -http_ssl
582 As -http, but force lookup for ssl classes subdir.
584 Note that for HTTPS, single-port Java applet delivery you can
586 set X11VNC_HTTPS_DOWNLOAD_WAIT_TIME to the max number of seconds
587 to wait for the applet download to finish. The default is 15.
588 -avahi
590 Use the Avahi/mDNS ZeroConf protocol to advertise this VNC
592 server to the local network. (Related terms: Rendezvous, Bon‐
593 jour). Depending on your setup, you may need to start avahi-
594 daemon and open udp port 5353 in your firewall.
595 You can set X11VNC_AVAHI_NAME, X11VNC_AVAHI_HOST, and/or
597 X11VNC_AVAHI_PORT environment variables to override the default
598 values. For example: -env X11VNC_AVAHI_NAME=wally
599 If the avahi API cannot be found at build time, a helper program
601 like avahi- publish(1) or dns- sd(1) will be tried
602 -mdns
604 Same as -avahi.
606 -zeroconf
608 Same as -avahi.
610 -connect string
612 For use with "vncviewer -listen" reverse connections. If string
614 has the form "host" or "host:port" the connection is made once
615 at startup.
616 Use commas for a list of host's and host:port's. E.g. -connect
618 host1,host2 or host1:0,host2:5678. Note that to reverse connect
619 to multiple hosts at the same time you will likely need to also
620 supply: -shared
621 Note that unlike most vnc servers, x11vnc will require a pass‐
623 word for reverse as well as for forward connections. (provided
624 password auth has been enabled, -rfbauth, etc) If you do not
625 want to require a password for reverse connections set
626 X11VNC_REVERSE_CONNECTION_NO_AUTH=1 in your environment before
627 starting x11vnc.
628 If string contains "/" it is instead interpreted as a file to
630 periodically check for new hosts. The first line is read and
631 then the file is truncated. Be careful about the location of
632 this file if x11vnc is running as root (e.g. via gdm(1) , etc).
633 Repeater mode: Some services provide an intermediate "vnc
635 repeater": http://www.uvnc.com/addons/repeater.html (and also
636 http://koti.mbnet.fi/jtko/ for linux port) that acts as a
637 proxy/gateway. Modes like these require an initial string to be
638 sent for the reverse connection before the VNC protocol is
639 started. Here are the ways to do this:
640 -connect pre=some_string+host:port -connect
642 pre128=some_string+host:port -connect repeater=ID:1234+host:port
643 -connect repeater=23.45.67.89::5501+host:port
644 SSVNC notation is also supported:
646 -connect repeater://host:port+ID:1234
648 As with normal -connect usage, if the repeater port is not sup‐
650 plied 5500 is assumed.
651 The basic idea is between the special tag, e.g. "pre=" and "+"
653 is the pre-string to be sent. Note that in this case host:port
654 is the repeater server, NOT the vnc viewer. Somehow the pre-
655 string tells the repeater server how to find the vnc viewer and
656 connect you to it.
657 In the case pre=some_string+host:port, "some_string" is simply
659 sent. In the case preNNN=some_string+host:port "some_string" is
660 sent in a null padded buffer of length NNN. repeater= is the
661 same as pre250=, this is the ultravnc repeater buffer size.
662 Strings like "\n" and "\r", etc. are expanded to newline and
664 carriage return. "\c" is expanded to "," since the connect
665 string is comma separated.
666 See also the -proxy option below for additional ways to plumb
668 reverse connections.
669 Reverse SSL: using -connect in -ssl mode makes x11vnc act as an
671 SSL client (initiates SSL connection) rather than an SSL server.
672 The idea is x11vnc might be connecting to stunnel on the viewer
673 side with the viewer in listening mode. If you do not want this
674 behavior, use -env X11VNC_DISABLE_SSL_CLIENT_MODE=1. With this
675 the viewer side can act as the SSL client as it normally does
676 for forward connections.
677 Reverse SSL Repeater mode: This will work, but note that if the
679 VNC Client does any sort of a 'Fetch Cert' action before con‐
680 necting, then the Repeater will likely drop the connection and
681 both sides will need to restart. Consider the use of -con‐
682 nect_or_exit and -loop300,2 to have x11vnc reconnect once to the
683 repeater after the fetch. You will probably also want to supply
684 -sslonly to avoid x11vnc thinking the delay in response means
685 the connection is VeNCrypt. The env var X11VNC_DIS‐
686 ABLE_SSL_CLIENT_MODE=1 discussed above may also be useful (i.e.
687 the viewer can do a forward connection as it normally does.)
688 IPv6: as of x11vnc 0.9.10 the -connect option should connect to
690 IPv6 hosts properly. If there are problems you can disable IPv6
691 by setting -DX11VNC_IPV6=0 in CPPFLAGS when configuring. If
692 there problems connecting to IPv6 hosts consider a relay like
693 the included inet6to4 script or the -proxy option.
694 -connect_or_exit str
696 As with -connect, except if none of the reverse connections suc‐
698 ceed, then x11vnc shuts down immediately
699 An easier to type alias for this option is '-coe'
701 By the way, if you do not want x11vnc to listen on ANY interface
703 use -rfbport 0 which is handy for the -connect_or_exit mode.
704 -proxy string
706 Use proxy in string (e.g. host:port) as a proxy for making
708 reverse connections (-connect or -connect_or_exit options).
709 Web proxies are supported, but note by default most of them only
711 support destination connections to ports 443 or 563, so this
712 might not be very useful (the viewer would need to listen on
713 that port or the router would have to do a port redirection).
714 A web proxy may be specified by either "host:port" or
716 "http://host:port" (the port is required even if it is the com‐
717 mon choices 80 or 8080)
718 SOCKS4, SOCKS4a, and SOCKS5 are also supported. SOCKS proxies
720 normally do not have restrictions on the destination port num‐
721 ber.
722 Use a format like this: socks://host:port or socks5://host:port.
724 Note that ssh -D does not support SOCKS4a, so use socks5://.
725 For socks:// SOCKS4 is used on a numerical IP and "localhost",
726 otherwise SOCKS4a is used (and so the proxy tries to do the DNS
727 lookup).
728 An experimental mode is "-proxy http://host:port/..." Note the
730 "/" after the port that distinguishes it from a normal web
731 proxy. The port must be supplied even if it is the default 80.
732 For this mode a GET is done to the supplied URL with the string
733 host=H&port=P appended. H and P will be the -connect reverse
734 connect host and port. Use the string "__END__" to disable the
735 appending. The basic idea here is that maybe some cgi script
736 provides the actual viewer hookup and tunnelling. How to actu‐
737 ally achieve this within cgi, php, etc. is not clear... A cus‐
738 tom web server or apache module would be straight-forward.
739 Another experimental mode is "-proxy ssh://user@host" in which
741 case a SSH tunnel is used for the proxying. "user@" is not
742 needed unless your unix username is different on "host". For a
743 non-standard SSH port use ssh://user@host:port. If proxies are
744 chained (see next paragraph) then the ssh one must be the first
745 one. If ssh-agent is not active, then the ssh password needs to
746 be entered in the terminal where x11vnc is running. Examples:
747 -connect localhost:0 -proxy ssh://me@friends-pc:2222
749 -connect snoopy:0 -proxy ssh://ssh.company.com
751 Multiple proxies may be chained together in case one needs to
753 ricochet off of a number of hosts to finally reach the VNC
754 viewer. Up to 3 may be chained, separate them by commas in the
755 order they are to be connected to. E.g.:
756 http://host1:port1,socks5://host2:port2 or three like:
757 first,second,third
758 IPv6: as of x11vnc 0.9.10 the -proxy option should connect to
760 IPv6 hosts properly. If there are problems you can disable IPv6
761 by setting -DX11VNC_IPV6=0 in CPPFLAGS when configuring. If
762 there problems connecting to IPv6 hosts consider a relay like
763 the included inet6to4 script.
764 -vncconnect, -novncconnect
766 Monitor the VNC_CONNECT X property set by the standard VNC pro‐
768 gram vncconnect(1). When the property is set to "host" or
769 "host:port" establish a reverse connection. Using xprop(1)
770 instead of vncconnect may work (see the FAQ). The -remote con‐
771 trol mechanism uses X11VNC_REMOTE channel, and this option dis‐
772 ables/enables it as well. Default: -vncconnect
773 To use different names for these X11 properties (e.g. to have
775 separate communication channels for multiple x11vnc's on the
776 same display) set the VNC_CONNECT or X11VNC_REMOTE env. vars. to
777 the string you want, for example: -env
778 X11VNC_REMOTE=X11VNC_REMOTE_12345 Both sides of the channel must
779 use the same unique name. The same can be done for the internal
780 X11VNC_TICKER property (heartbeat and timestamp) if desired.
781 -allow host1[,host2..]
783 Only allow client connections from hosts matching the comma sep‐
785 arated list of hostnames or IP addresses. By ending in a ".",
786 it can also be a numerical IP prefix, e.g. "192.168.100." to
787 match a simple subnet, for more control build LibVNCServer with
788 libwrap support (See the FAQ). If the list contains a "/" it
789 instead is a interpreted as a file containing addresses or pre‐
790 fixes that is re-read each time a new client connects. Lines
791 can be commented out with the "#" character in the usual way.
792 -allow applies in -ssl mode, but not in -stunnel mode.
794 IPv6: as of x11vnc 0.9.10 a host can be specified in IPv6 numer‐
796 ical format, e.g. 2001:4860:b009::93
797 Env. vars: Set -env X11VNC_DEBUG_ACCESS=1 to print out debugging
799 info during the check_access() call. Set -env
800 X11VNC_ALLOW_FULLMATCH=1 to force a full string match, that is,
801 no subnet "." matching will be performed.
802 Unix sockets: if -unixsock is being used and you want to limit
804 TCP access also you must also include the path to the unix
805 socket prefixed with "unix=" in the allow list, e.g.: -allow
806 192.168.100.3,unix=/tmp/mysock If the socket is not a named one,
807 e.g. created via socketpair(2) with -inetd, then you must supply
808 the generic name x11vnc gives to it, e.g. -allow
809 192.168.100.3,UNNAMED_AF_UNIX In both cases it must be an exact
810 string match to be allowed to connect. Note that since you com‐
811 pletely control these local non-TCP access methods by file sys‐
812 tem permissions, etc., it is not useful to guard against them
813 with -allow, however you still need to have them in the allow
814 list to let them connect.
815 -localhost
817 Basically the same as "-allow 127.0.0.1".
819 Note: if you want to restrict which network interface x11vnc
821 listens on, see the -listen option below. E.g. "-listen local‐
822 host" or "-listen 192.168.3.21". As a special case, the option
823 "-localhost" implies "-listen localhost".
824 A rare case, but for non-localhost -listen usage, if you use the
826 remote control mechanism (-R) to change the -listen interface
827 you may need to manually adjust the -allow list (and vice versa)
828 to avoid situations where no connections (or too many) are
829 allowed.
830 If you do not want x11vnc to listen on ANY TCP interface (evi‐
832 dently you are using -connect or -connect_or_exit, or plan to
833 use remote control: -R connect:host, or to use -unixsock), spec‐
834 ify -rfbport 0
835 IPv6: if IPv6 is supported, this option automatically implies
837 the IPv6 loopback address '::1' as well.
838 -unixsock str
840 In addition to the regular TCP port, listen on the unix socket
842 (AF_UNIX) 'str' for incoming connections. This mode is for
843 either local connections or a tunnel endpoint where one wants
844 the file permission of the unix socket file to determine what
845 can connect to it. Example: mkdir ~/s; chmod 700 ~/s; x11vnc
846 -unixsock ~/s/mysock -rfbport 0 ... same as: x11vnc -unixsock‐
847 only ~/s/mysock ... (see -unixsockonly below.)
848 This mode currently requires the modified libvncserver bundled
850 in the the x11vnc 0.9.13 tarball and later.
851 Note that the SSVNC unix vncviewer can connect to unix sockets,
853 for example: ssvnc -viewer unix=./s/mysock
854 As a special mechanism, if 'str' for either -unixsock or -unix‐
856 sockonly is of the form "fd=n" where n is a non-negative decimal
857 integer, then instead of creating a unix socket, that file
858 descriptor (assumed already opened and O_RDWR) will be attached
859 as a VNC client. Perhaps the program that execs x11vnc has cre‐
860 ated a socketpair(2) to communicate over. Use this mechanism if
861 -inetd (which is basically fd=0) is not flexible enough for you.
862 -unixsockonly str
864 Listen on unix socket 'str' only, no TCP ports. First note that
866 one can disable all tcp listening ports by specifying '-rfbport
867 0'. The option '-unixsockonly str' is functionally equivalent to
868 '-unixsock str -rfbport 0'
869 -listen6 str
871 When in IPv6 listen mode "-6", listen only on the network inter‐
873 face with address str. It also works for link scope addresses
874 (fe80::219:dbff:fee5:3f92%eth0) and IPv6 hostname strings (e.g.
875 ipv6.google.com.) Use LibVNCServer -listen option for the IPv4
876 interface.
877 -nolookup
879 Do not use gethostbyname() or gethostbyaddr() to look up host
881 names or IP numbers. Use this if name resolution is incorrectly
882 set up and leads to long pauses as name lookups time out, etc.
883 -input string
885 Fine tuning of allowed user input. If string does not contain a
887 comma "," the tuning applies only to normal clients. Otherwise
888 the part before "," is for normal clients and the part after for
889 view-only clients. "K" is for Keystroke input, "M" for Mouse-
890 motion input, "B" for Button-click input, "C" is for Clipboard
891 input, and "F" is for File transfer (ultravnc only). Their
892 presence in the string enables that type of input. E.g. "-input
893 M" means normal users can only move the mouse and "-input
894 KMBCF,M" lets normal users do anything and enables view-only
895 users to move the mouse. This option is ignored when a global
896 -viewonly is in effect (all input is discarded in that case).
897 -grabkbd
899 When VNC viewers are connected, attempt to the grab the keyboard
901 so a (non-malicious) user sitting at the physical display is not
902 able to enter keystrokes. This method uses XGrabKeyboard(3X11)
903 and so it is not secure and does not rule out the person at the
904 physical display injecting keystrokes by flooding the server
905 with them, grabbing the keyboard himself, etc. Some degree of
906 cooperation from the person at the display is assumed. This is
907 intended for remote help-desk or educational usage modes.
908 Note: on some recent (12/2010) X servers and/or desktops,
910 -grabkbd no longer works: it prevents the window manager from
911 resizing windows and similar things. Try -ungrabboth below
912 (might not work.)
913 -grabptr
915 As -grabkbd, but for the mouse pointer using XGrabPointer(3X11).
917 Unfortunately due to the way the X server works, the mouse can
918 still be moved around by the user at the physical display, but
919 he will not be able to change window focus with it. Also some
920 window managers that call XGrabServer(3X11) for resizes, etc,
921 will act on the local user's input. Again, some degree of coop‐
922 eration from the person at the display is assumed.
923 -ungrabboth
925 Whenever there is any input (either keyboard or pointer), ungrab
927 *both* the keyboard and the pointer while injecting the syn‐
928 thetic input. This is to allow window managers, etc. a chance
929 to grab.
930 -grabalways
932 Apply both -grabkbd and -grabptr even when no VNC viewers are
934 connected. If you only want one of them, use the -R remote con‐
935 trol to turn the other back on, e.g. -R nograbptr.
936 (PASSWORDS: Note that the LibVNCServer password options
938 "-rfbauth file" and "-passwd str" are described at the bottom of
939 the help output.)
940 -viewpasswd string
942 Supply a 2nd password for view-only logins. The -passwd (full-
944 access) password must also be supplied.
945 -passwdfile filename
947 Specify the LibVNCServer password via the first line of the file
949 filename (instead of via -passwd on the command line where oth‐
950 ers might see it via ps(1) ).
951 See the descriptions below for how to supply multiple passwords,
953 view-only passwords, to specify external programs for the
954 authentication, and other features.
955 If the filename is prefixed with "rm:" it will be removed after
957 being read. Perhaps this is useful in limiting the readability
958 of the file. In general, the password file should not be read‐
959 able by untrusted users (BTW: neither should the VNC -rfbauth
960 file: it is NOT encrypted, only obscured with a fixed key).
961 If the filename is prefixed with "read:" it will periodically be
963 checked for changes and reread. It is guaranteed to be reread
964 just when a new client connects so that the latest passwords
965 will be used.
966 If filename is prefixed with "cmd:" then the string after the
968 ":" is run as an external command: the output of the command
969 will be interpreted as if it were read from a password file (see
970 below). If the command does not exit with 0, then x11vnc termi‐
971 nates immediately. To specify more than 1000 passwords this way
972 set X11VNC_MAX_PASSWDS before starting x11vnc. The environment
973 variables are set as in -accept.
974 Note that due to the VNC protocol only the first 8 characters of
976 a password are used (DES key).
977 If filename is prefixed with "custom:" then a custom password
979 checker is supplied as an external command following the ":".
980 The command will be run when a client authenticates. If the
981 command exits with 0 the client is accepted, otherwise it is
982 rejected. The environment variables are set as in -accept.
983 The standard input to the custom command will be a decimal digit
985 "len" followed by a newline. "len" specifies the challenge size
986 and is usually 16 (the VNC spec). Then follows len bytes which
987 is the random challenge string that was sent to the client. This
988 is then followed by len more bytes holding the client's response
989 (i.e. the challenge string encrypted via DES with the user pass‐
990 word in the standard situation).
991 The "custom:" scheme can be useful to implement dynamic pass‐
993 words or to implement methods where longer passwords and/or dif‐
994 ferent encryption algorithms are used. The latter will require
995 customizing the VNC client as well. One could create an MD5SUM
996 based scheme for example. See also -unixpw_cmd below.
997 File format for -passwdfile:
999 If multiple non-blank lines exist in the file they are all taken
1001 as valid passwords. Blank lines are ignored. Password lines
1002 may be "commented out" (ignored) if they begin with the charac‐
1003 ter "#" or the line contains the string "__SKIP__". Lines may
1004 be annotated by use of the "__COMM__" string: from it to the end
1005 of the line is ignored. An empty password may be specified via
1006 the "__EMPTY__" string on a line by itself (note your viewer
1007 might not accept empty passwords).
1008 If the string "__BEGIN_VIEWONLY__" appears on a line by itself,
1010 the remaining passwords are used for viewonly access. For com‐
1011 patibility, as a special case if the file contains only two
1012 password lines the 2nd one is automatically taken as the
1013 viewonly password. Otherwise the "__BEGIN_VIEWONLY__" token
1014 must be used to have viewonly passwords. (tip: make the 3rd and
1015 last line be "__BEGIN_VIEWONLY__" to have 2 full-access pass‐
1016 words)
1017 -showrfbauth filename
1019 Print to the screen the obscured VNC password kept in the
1021 rfbauth file filename and then exit.
1022 -usepw
1024 If no other password method was supplied on the command line,
1026 first look for ~/.vnc/passwd and if found use it with -rfbauth;
1027 next, look for ~/.vnc/passwdfile and use it with -passwdfile;
1028 otherwise, prompt the user for a password to create
1029 ~/.vnc/passwd and use it with the -rfbauth option. If none of
1030 these succeed x11vnc exits immediately.
1031 -storepasswd pass file
1033 Store password pass as the VNC password in the file file. Once
1035 the password is stored the program exits. Use the password via
1036 "-rfbauth file"
1037 If called with no arguments, "x11vnc -storepasswd", the user is
1039 prompted for a password and it is stored in the file
1040 ~/.vnc/passwd. Called with one argument, that will be the file
1041 to store the prompted password in.
1042 -nopw
1044 Disable the big warning message when you use x11vnc without some
1046 sort of password.
1047 -accept string
1049 Run a command (possibly to prompt the user at the X11 display)
1051 to decide whether an incoming client should be allowed to con‐
1052 nect or not. string is an external command run via system(3) or
1053 some special cases described below. Be sure to quote string if
1054 it contains spaces, shell characters, etc. If the external com‐
1055 mand returns 0 the client is accepted, otherwise the client is
1056 rejected. See below for an extension to accept a client view-
1057 only.
1058 If x11vnc is running as root (say from inetd(8) or from display
1060 managers xdm(1) , gdm(1) , etc), think about the security impli‐
1061 cations carefully before supplying this option (likewise for the
1062 -gone option).
1063 Environment: The RFB_CLIENT_IP environment variable will be set
1065 to the incoming client IP number and the port in RFB_CLIENT_PORT
1066 (or -1 if unavailable). Similarly, RFB_SERVER_IP and
1067 RFB_SERVER_PORT (the x11vnc side of the connection), are set to
1068 allow identification of the tcp virtual circuit. The x11vnc
1069 process id will be in RFB_X11VNC_PID, a client id number in
1070 RFB_CLIENT_ID, and the number of other connected clients in
1071 RFB_CLIENT_COUNT. RFB_MODE will be "accept". RFB_STATE will be
1072 PROTOCOL_VERSION, SECURITY_TYPE, AUTHENTICATION, INITIALISATION,
1073 NORMAL, or UNKNOWN indicating up to which state the client has
1074 achieved. RFB_LOGIN_VIEWONLY will be 0, 1, or -1 (unknown).
1075 RFB_USERNAME, RFB_LOGIN_TIME, and RFB_CURRENT_TIME may also be
1076 set.
1077 If string is "popup" then a builtin popup window is used. The
1079 popup will time out after 120 seconds, use "popup:N" to modify
1080 the timeout to N seconds (use 0 for no timeout).
1081 In the case of "popup" and when the -unixpw option is specified,
1083 then a *second* window will be popped up after the user success‐
1084 fully logs in via his UNIX password. This time the user will be
1085 identified as UNIX:username@hostname, the "UNIX:" prefix indi‐
1086 cates which user the viewer logged as via -unixpw. The first
1087 popup is only for whether to allow him to even *try* to login
1088 via unix password.
1089 If string is "xmessage" then an xmessage(1) invocation is used
1091 for the command. xmessage must be installed on the machine for
1092 this to work.
1093 Both "popup" and "xmessage" will present an option for accepting
1095 the client "View-Only" (the client can only watch). This option
1096 will not be presented if -viewonly has been specified, in which
1097 case the entire display is view only.
1098 If the user supplied command is prefixed with something like
1100 "yes:0,no:*,view:3 mycommand ..." then this associates the
1101 numerical command return code with the actions: accept, reject,
1102 and accept-view-only, respectively. Use "*" instead of a number
1103 to indicate the default action (in case the command returns an
1104 unexpected value). E.g. "no:*" is a good choice.
1105 Note that x11vnc blocks while the external command or popup is
1107 running (other clients may see no updates during this period).
1108 So a person sitting a the physical display is needed to respond
1109 to an popup prompt. (use a 2nd x11vnc if you lock yourself out).
1110 More -accept tricks: use "popupmouse" to only allow mouse clicks
1112 in the builtin popup to be recognized. Similarly use "popupkey"
1113 to only recognize keystroke responses. These are to help avoid
1114 the user accidentally accepting a client by typing or clicking.
1115 All 3 of the popup keywords can be followed by +N+M to supply a
1116 position for the popup window. The default is to center the
1117 popup window.
1118 -afteraccept string
1120 As -accept, except to run a user supplied command after a client
1122 has been accepted and authenticated. RFB_MODE will be set to
1123 "afteraccept" and the other RFB_* variables are as in -accept.
1124 Unlike -accept, the command return code is not interpreted by
1125 x11vnc. Example: -afteraccept 'killall xlock &'
1126 -gone string
1128 As -accept, except to run a user supplied command when a client
1130 goes away (disconnects). RFB_MODE will be set to "gone" and the
1131 other RFB_* variables are as in -accept. The "popup" actions
1132 apply as well. Unlike -accept, the command return code is not
1133 interpreted by x11vnc. Example: -gone 'xlock &'
1134 -unixpw [list]
1136 Use Unix username and password authentication. x11vnc will use
1138 the su(1) program to verify the user's password. [list] is an
1139 optional comma separated list of allowed Unix usernames. If the
1140 [list] string begins with the character "!" then the entire list
1141 is taken as an exclude list. See below for per-user options
1142 that can be applied.
1143 A familiar "login:" and "Password:" dialog is presented to the
1145 user on a black screen inside the vncviewer. The connection is
1146 dropped if the user fails to supply the correct password in 3
1147 tries or does not send one before a 45 second timeout. Existing
1148 clients are view-only during this period.
1149 If the first character received is "Escape" then the unix user‐
1151 name will not be displayed after "login:" as it is typed. This
1152 could be of use for VNC viewers that automatically type the
1153 username and password.
1154 Since the detailed behavior of su(1) can vary from OS to OS and
1156 for local configurations, test the mode before deployment to
1157 make sure it is working properly. x11vnc will attempt to be
1158 conservative and reject a login if anything abnormal occurs.
1159 One case to note: FreeBSD and the other BSD's by default it is
1161 impossible for the user running x11vnc to validate his *own*
1162 password via su(1) (commenting out the pam_self.so entry in
1163 /etc/pam.d/su eliminates this behavior). So the x11vnc login
1164 will always *FAIL* for this case (even when the correct password
1165 is supplied).
1166 A possible workaround for this on *BSD would be to start x11vnc
1168 as root with the "-users +nobody" option to immediately switch
1169 to user nobody where the su'ing will proceed normally.
1170 Another source of potential problems are PAM modules that prompt
1172 for extra info, e.g. password aging modules. These logins will
1173 fail as well even when the correct password is supplied.
1174 **IMPORTANT**: to prevent the Unix password being sent in *clear
1176 text* over the network, one of two schemes will be enforced: 1)
1177 the -ssl builtin SSL mode, or 2) require both -localhost and
1178 -stunnel be enabled.
1179 Method 1) ensures the traffic is encrypted between viewer and
1181 server. A PEM file will be required, see the discussion under
1182 -ssl below (under some circumstances a temporary one can be
1183 automatically generated).
1184 Method 2) requires the viewer connection to appear to come from
1186 the same machine x11vnc is running on (e.g. from a ssh -L port
1187 redirection). And that the -stunnel SSL mode be used for
1188 encryption over the network. (see the description of -stunnel
1189 below).
1190 Note: as a convenience, if you ssh(1) in and start x11vnc it
1192 will check if the environment variable SSH_CONNECTION is set and
1193 appears reasonable. If it does, then the -ssl or -stunnel
1194 requirement will be dropped since it is assumed you are using
1195 ssh for the encrypted tunnelling. -localhost is still enforced.
1196 Use -ssl or -stunnel to force SSL usage even if SSH_CONNECTION
1197 is set.
1198 To override the above restrictions you can set environment vari‐
1200 ables before starting x11vnc:
1201 Set UNIXPW_DISABLE_SSL=1 to disable requiring either -ssl or
1203 -stunnel (as under SSH_CONNECTION.) Evidently you will be using
1204 a different method to encrypt the data between the vncviewer and
1205 x11vnc: perhaps ssh(1) or an IPSEC VPN. -localhost is still
1206 enforced (however, see the next paragraph.)
1207 Set UNIXPW_DISABLE_LOCALHOST=1 to disable the -localhost
1209 requirement in -unixpw modes. One should never do this (i.e.
1210 allow the Unix passwords to be sniffed on the network.) This
1211 also disables the localhost requirement for reverse connections
1212 (see below.)
1213 Note that use of -localhost with ssh(1) (and no -unixpw) is
1215 roughly the same as requiring a Unix user login (since a Unix
1216 password or the user's public key authentication is used by sshd
1217 on the machine where x11vnc runs and only local connections from
1218 that machine are accepted).
1219 Regarding reverse connections (e.g. -R connect:host and -connect
1221 host), when the -localhost constraint is in effect then reverse
1222 connections can only be used to connect to the same machine
1223 x11vnc is running on (default port 5500). Please use a ssh or
1224 stunnel port redirection to the viewer machine to tunnel the
1225 reverse connection over an encrypted channel.
1226 In -inetd mode the Method 1) will be enforced (not Method 2).
1228 With -ssl in effect reverse connections are disabled. If you
1229 override this via env. var, be sure to also use encryption from
1230 the viewer to inetd. Tip: you can also have your own stunnel
1231 spawn x11vnc in -inetd mode (thereby bypassing inetd). See the
1232 FAQ for details.
1233 The user names in the comma separated [list] may have per-user
1235 options after a ":", e.g. "fred:opts" where "opts" is a "+" sep‐
1236 arated list of "viewonly", "fullaccess", "input=XXXX", or
1237 "deny", e.g. "karl,wally:viewonly,boss:input=M". For "input="
1238 it is the K,M,B,C described under -input.
1239 If an item in the list is "*" that means those options apply to
1241 all users. It ALSO implies all users are allowed to log in
1242 after supplying a valid password. Use "deny" to explicitly deny
1243 some users if you use "*" to set a global option. If [list]
1244 begins with the "!" character then "*" is ignored for checking
1245 if the user is allowed, but the option values associated with it
1246 do apply as normal.
1247 There are also some utilities for checking passwords if [list]
1249 starts with the "%" character. See the quick_pw() function for
1250 more details. Description: "%-" or "%stdin" means read one line
1251 from stdin of form user:pass. "%stdin2" means read the username
1252 from the first stdin line and the password from the second stdin
1253 line. "%pipe" means the first line of stdin is user:pass, if
1254 UNIXPW_CMD_STDIN is set then that string is piped into the
1255 UNIXPW_CMD command (see next paragraph), otherwise the 2nd line
1256 of stdin is read, if it a positive number that many bytes are
1257 read from stdin and are piped into the command, if it is -1 then
1258 one more line, up to 8000 bytes, is read from stdin and piped to
1259 the command. "%env" means user:pass is in UNIXPW env var. A
1260 leading "%/" or "%." means read the first line from the filename
1261 that follows after the % character. % by itself means prompt for
1262 the username and password. Otherwise: %user:pass For example:
1263 -unixpw %fred:swordfish For the other cases user:pass is read
1264 from the indicated source. If the password is correct 'Y user'
1265 is printed and the program exit code is 0. If the password is
1266 incorrect it prints 'N user' and the exit code is 1. If there
1267 is some other error the exit code is 2. This feature enables
1268 x11vnc to be a general unix user password checking tool; it
1269 could be used from scripts or other programs. These % password
1270 checks, except for "%pipe", also apply to the -unixpw_nis and
1271 -unixpw_cmd options.
1272 For the % password check, if the env. var. UNIXPW_CMD is set to
1274 a command then it is run as the user (assuming the password is
1275 correct.) The output of the command is not printed, the program
1276 or script must manage that by some other means. The exit code
1277 of x11vnc will depend on the exit code of the command that is
1278 run.
1279 When interacting with /bin/su to login x11vnc tries to emulate
1281 typing in the pty, set X11VNC_SLOW_PW_MS to tune this (default
1282 50 ms between characters.)
1283 Use -nounixpw to disable unixpw mode if it was enabled earlier
1285 in the cmd line (e.g. -svc mode)
1286 -unixpw_nis [list]
1288 As -unixpw above, however do not use su(1) but rather use the
1290 traditional getpwnam(3) + crypt(3) method to verify passwords.
1291 All of the above -unixpw options and constraints apply.
1292 This mode requires that the encrypted passwords be readable.
1294 Encrypted passwords stored in /etc/shadow will be inaccessible
1295 unless x11vnc is run as root.
1296 This is called "NIS" mode simply because in most NIS setups user
1298 encrypted passwords are accessible (e.g. "ypcat passwd") by an
1299 ordinary user and so that user can authenticate ANY user.
1300 NIS is not required for this mode to work (only that getpwnam(3)
1302 return the encrypted password is required), but it is unlikely
1303 it will work (as an ordinary user) for most modern environments
1304 unless NIS is available. On the other hand, when x11vnc is run
1305 as root it will be able to to access /etc/shadow even if NIS is
1306 not available (note running as root is often done when running
1307 x11vnc from inetd and xdm/gdm/kdm).
1308 Looked at another way, if you do not want to use the su(1)
1310 method provided by -unixpw (i.e. su_verify()), you can run
1311 x11vnc as root and use -unixpw_nis. Any users with passwords in
1312 /etc/shadow can then be authenticated.
1313 In -unixpw_nis mode, under no circumstances is x11vnc's user
1315 password verifying function based on su called (i.e. the func‐
1316 tion su_verify() that runs /bin/su in a pseudoterminal to verify
1317 passwords.) However, if -unixpw_nis is used in conjunction with
1318 the -find and -create -display WAIT:... modes then, if x11vnc is
1319 running as root, /bin/su may be called externally to run the
1320 find or create commands.
1321 -unixpw_cmd cmd
1323 As -unixpw above, however do not use su(1) but rather run the
1325 externally supplied command cmd. The first line of its stdin
1326 will be the username and the second line the received password.
1327 If the command exits with status 0 (success) the VNC user will
1328 be accepted. It will be rejected for any other return status.
1329 Dynamic passwords and non-unix passwords, e.g. LDAP, can be
1331 implemented this way by providing your own custom helper pro‐
1332 gram. Note that the remote viewer is given 3 tries to enter the
1333 correct password, and so the program may be called in a row that
1334 many (or more) times.
1335 If a list of allowed users is needed to limit who can log in,
1337 use -unixpw [list] in addition to this option.
1338 In FINDDISPLAY and FINDCREATEDISPLAY modes the cmd will also be
1340 run with the RFB_UNIXPW_CMD_RUN env. var. non-empty and set to
1341 the corresponding display find/create command. The first two
1342 lines of input are the username and passwd as in the normal case
1343 described above. To support FINDDISPLAY and FINDCREATEDISPLAY,
1344 cmd should run the requested command as the user (and most
1345 likely refusing to run it if the password is not correct.) Here
1346 is an example script (note it has a hardwired bogus password
1347 "abc"!)
1348 #!/bin/sh # Example x11vnc -unixpw_cmd script. # Read the first
1350 two lines of stdin (user and passwd) read user read pass
1351 debug=0 if [ $debug = 1 ]; then echo "user: $user" 1>&2 echo
1353 "pass: $pass" 1>&2 env | egrep -i 'rfb|vnc' 1>&2 fi
1354 # Check if the password is valid. # (A real example would use
1356 ldap lookup, etc!) if [ "X$pass" != "Xabc" ]; then exit 1 #
1357 incorrect password fi
1358 if [ "X$RFB_UNIXPW_CMD_RUN" = "X" ]; then exit 0 # correct
1360 password else # Run the requested command (finddisplay) if [
1361 $debug = 1 ]; then echo "run: $RFB_UNIXPW_CMD_RUN" 1>&2 fi exec
1362 /bin/su - "$user" -c "$RFB_UNIXPW_CMD_RUN" fi exit 1
1363 In -unixpw_cmd mode, under no circumstances is x11vnc's user
1365 password verifying function based on su called (i.e. the func‐
1366 tion su_verify() that runs /bin/su in a pseudoterminal to verify
1367 passwords.) It is up to the supplied unixpw_cmd to do user
1368 switching if desired and if it has the permissions to do so.
1369 See also "-passwdfile custom:..." above for a non unix username
1371 based custom password checking interface.
1372 -find
1374 Find the user's display using FINDDISPLAY. This is an alias for
1376 "-display WAIT:cmd=FINDDISPLAY".
1377 Note: if a -display occurs later on the command line it will
1379 override the -find setting.
1380 For this and the next few options see -display WAIT:... below
1382 for all of the details.
1383 -finddpy
1385 Run the FINDDISPLAY program, print out the found display (if
1387 any) and exit. Output is like: DISPLAY=:0.0 DIS‐
1388 PLAY=:0.0,XPID=12345 or DISPLAY=:0.0,VT=7. XPID is the process
1389 ID of the found X server. VT is the Linux virtual terminal of
1390 the X server.
1391 -listdpy
1393 Have the FINDDISPLAY program list all of your displays (i.e. all
1395 the X displays on the local machine that you have access rights
1396 to). x11vnc then exits.
1397 -findauth [disp]
1399 Apply the -find/-finddpy heuristics to try to guess the XAUTHOR‐
1401 ITY file for DISPLAY 'disp'. If 'disp' is not supplied, then
1402 the value in the -display on the cmdline is used; failing that
1403 $DISPLAY is used; and failing that ":0" is used. x11vnc then
1404 exits.
1405 If nothing is printed out, that means no XAUTHORITY was found
1407 for 'disp'; i.e. failure. If "XAUTHORITY=" is printed out, that
1408 means use the default (i.e. do not set XAUTHORITY). If "XAU‐
1409 THORITY=/path/to/file" is printed out, then use that file.
1410 XDM/GDM/KDM: if you are running x11vnc as root and want to find
1412 the XAUTHORITY before anyone has logged into an X session yet,
1413 use: x11vnc -env FD_XDM=1 -findauth ... (This will also find
1414 the XAUTHORITY if a user is already logged into the X session.)
1415 When running as root, FD_XDM=1 will be tried if the initial
1416 -findauth fails.
1417 -create
1419 First try to find the user's display using FINDDISPLAY, if that
1421 doesn't succeed create an X session via the FINDCREATEDISPLAY
1422 method. This is an alias for "-display WAIT:cmd=FINDCREATEDIS‐
1423 PLAY-Xvfb".
1424 Note: if a -display occurs later on the command line it will
1426 override the -create setting.
1427 SSH NOTE: for both -find and -create you can (should!) add the
1429 "-localhost" option to force SSH tunnel access.
1430 -xdummy
1432 As in -create, except Xdummy instead of Xvfb.
1434 -xvnc
1436 As in -create, except Xvnc instead of Xvfb.
1438 -xvnc_redirect
1440 As in -create, except Xvnc.redirect instead of Xvfb.
1442 -xdummy_xvfb
1444 Sets WAIT:cmd=FINDCREATEDISPLAY-Xdummy,Xvfb
1446 -create_xsrv str
1448 Sets WAIT:cmd=FINDCREATEDISPLAY-<str> Can be on cmdline after
1450 anything that sets WAIT:.. and other things (e.g. -svc, -xdmsvc)
1451 to adjust the X server list. Example: -svc ... -create_xsrv
1452 Xdummy,X
1453 -svc
1455 Terminal services mode based on SSL access. Alias for -display
1457 WAIT:cmd=FINDCREATEDISPLAY-Xvfb -unixpw -users unixpw= -ssl SAVE
1458 Also "-service".
1459 Note: if a -display, -unixpw, -users, or -ssl occurs later on
1461 the command line it will override the -svc setting.
1462 -svc_xdummy
1464 As -svc except Xdummy instead of Xvfb.
1466 -svc_xvnc
1468 As -svc except Xvnc instead of Xvfb.
1470 -svc_xdummy_xvfb
1472 As -svc with Xdummy,Xvfb.
1474 -xdmsvc
1476 Display manager Terminal services mode based on SSL. Alias for
1478 -display WAIT:cmd=FINDCREATEDISPLAY-Xvfb.xdmcp -unixpw -users
1479 unixpw= -ssl SAVE Also "-xdm_service".
1480 Note: if a -display, -unixpw, -users, or -ssl occurs later on
1482 the command line it will override the -xdmsvc setting.
1483 To create a session a user will have to first log in to the
1485 -unixpw dialog and then log in again to the XDM/GDM/KDM prompt.
1486 Subsequent re-connections will only require the -unixpw pass‐
1487 word. See the discussion under -display WAIT:... for more
1488 details about XDM, etc configuration.
1489 Remember to enable XDMCP in the xdm-config, gdm.conf, or kdmrc
1491 configuration file. See -display WAIT: for more info.
1492 -sshxdmsvc
1494 Display manager Terminal services mode based on SSH. Alias for
1496 -display WAIT:cmd=FINDCREATEDISPLAY-Xvfb.xdmcp -localhost.
1497 The -localhost option constrains connections to come in via a
1499 SSH tunnel (which will require a login). To create a session a
1500 user will also have to log into the XDM GDM KDM prompt. Subse‐
1501 quent re-connections will only only require the SSH login. See
1502 the discussion under -display WAIT:... for more details about
1503 XDM, etc configuration.
1504 Remember to enable XDMCP in the xdm-config, gdm.conf, or kdmrc
1506 configuration file. See -display WAIT: for more info.
1507 -unixpw_system_greeter
1509 Present a "Press 'Escape' for System Greeter" option to the con‐
1511 necting VNC client in combined -unixpw and xdmcp FINDCREATEDIS‐
1512 PLAY modes (e.g. -xdmsvc).
1513 Normally in a -unixpw mode the VNC client must supply a valid
1515 username and password to gain access. However, if -unixpw_sys‐
1516 tem_greeter is supplied AND the FINDCREATEDISPLAY command
1517 matches 'xdmcp', then the user has the option to press Escape
1518 and then get a XDM/GDM/KDM login/greeter panel instead. They
1519 will then supply a username and password directly to the
1520 greeter.
1521 Otherwise, in xdmcp FINDCREATEDISPLAY mode the user must supply
1523 his username and password TWICE. First to the initial unixpw
1524 login dialog, and second to the subsequent XDM/GDM/KDM greeter.
1525 Note that if the user re-connects and supplies his username and
1526 password in the unixpw dialog the xdmcp greeter is skipped and
1527 he is connected directly to his existing X session. So the
1528 -unixpw_system_greeter option avoids the extra password at X
1529 session creation time.
1530 Example: x11vnc -xdmsvc -unixpw_system_greeter See -unixpw and
1532 -display WAIT:... for more info.
1533 The special options after a colon at the end of the username
1535 (e.g. user:solid) described under -display WAIT: are also
1536 applied in this mode if they are typed in before the user hits
1537 Escape. The username is ignored but the colon options are not.
1538 The default message is 2 lines in a small font, set the env.
1540 var. X11VNC_SYSTEM_GREETER1=true for a 1 line message in a
1541 larger font.
1542 If the user pressed Escape the FINDCREATEDISPLAY command will be
1544 run with the env. var. X11VNC_XDM_ONLY=1.
1545 Remember to enable XDMCP in the xdm-config, gdm.conf, or kdmrc
1547 configuration file. See -display WAIT: for more info.
1548 -redirect port
1550 As in FINDCREATEDISPLAY-Xvnc.redirect mode except redirect imme‐
1552 diately (i.e. without X session finding or creation) to a VNC
1553 server listening on port. You can also supply host:port to redi‐
1554 rect to a different machine.
1555 If 0 <= port < 200 it is taken as a VNC display (5900 is added
1557 to get the actual port), if port < 0 then -port is used.
1558 Probably the only reason to use the -redirect option is in con‐
1560 junction with SSL support, e.g. -ssl SAVE. This provides an
1561 easy way to add SSL encryption to a VNC server that does not
1562 support SSL (e.g. Xvnc or vnc.so) In fact, the protocol does not
1563 even need to be VNC, and so "-rfbport port1 -ssl SAVE -redirect
1564 host:port2" can act as a replacement for stunnel(1).
1565 This mode only allows one redirected connection. The -forever
1567 option does not apply. Use -inetd or -loop for persistent ser‐
1568 vice.
1569 -display WAIT:...
1571 A special usage mode for the normal -display option. Useful
1573 with -unixpw, but can be used independently of it. If the dis‐
1574 play string begins with WAIT: then x11vnc waits until a VNC
1575 client connects before opening the X display (or -rawfb device).
1576 This could be useful for delaying opening the display for cer‐
1578 tain usage modes (say if x11vnc is started at boot time and no X
1579 server is running or users logged in yet).
1580 If the string is, e.g. WAIT:0.0 or WAIT:1, i.e. "WAIT" in front
1582 of a normal X display, then that indicated display is used.
1583 One can also insert a geometry between colons, e.g.
1585 WAIT:1280x1024:... to set the size of the display the VNC client
1586 first attaches to since some VNC viewers will not automatically
1587 adjust to a new framebuffer size.
1588 A more interesting case is like this:
1590 WAIT:cmd=/usr/local/bin/find_display
1592 in which case the command after "cmd=" is run to dynamically
1594 work out the DISPLAY and optionally the XAUTHORITY data. The
1595 first line of the command output must be of the form DIS‐
1596 PLAY=<xdisplay>. On Linux if the virtual terminal is known
1597 append ",VT=n" to this string and the chvt(1) program will also
1598 be run. Any remaining output is taken as XAUTHORITY data. It
1599 can be either of the form XAUTHORITY=<file> or raw xauthority
1600 data for the display. For example;
1601 xauth extract - $DISPLAY"
1603 NOTE: As specified in the previous paragraph, you can supply
1605 your own WAIT:cmd=... program or script, BUT there are two very
1606 useful *BUILT-IN* ones: FINDDISPLAY (alias -find above) and
1607 FINDCREATEDISPLAY (alias -create above.) Most people use these
1608 instead of creating their own script. Read the following (espe‐
1609 cially the BUILT-IN modes sections) to see how to configure
1610 these two useful builtin -display WAIT: modes.
1611 In the case of -unixpw (and -unixpw_nis only if x11vnc is run‐
1613 ning as root), then the cmd= command is run as the user who just
1614 authenticated via the login and password prompt.
1615 In the case of -unixpw_cmd, the commands will also be run as the
1617 logged-in user, as long as the user-supplied helper program sup‐
1618 ports RFB_UNIXPW_CMD_RUN (see the -unixpw_cmd option.)
1619 Also in the case of -unixpw, the user logging in can place a
1621 colon at the end of her username and supply a few options:
1622 scale=, scale_cursor= (or sc=), solid (or so), id=, clear_mods
1623 (or cm), clear_keys (or ck), clear_all (or ca), repeat, speeds=
1624 (or sp=), readtimeout= (or rd=), viewonly (or vo), nodisplay=
1625 (or nd=), rotate= (or ro=), or noncache (or nc), all separated
1626 by commas if there is more than one. After the user logs in
1627 successfully, these options will be applied to the VNC screen.
1628 For example,
1629 login: fred:scale=3/4,sc=1,repeat Password: ...
1631 login: runge:sp=modem,rd=120,solid
1633 for convenience m/n implies scale= e.g. fred:3/4 If you type
1635 and enter your password incorrectly, to retrieve your long
1636 "login:" line press the Up arrow once (before typing anything
1637 else).
1638 Most of these colon options only apply to the builtin FINDDIS‐
1640 PLAY and FINDCREATEDISPLAY modes, but note that they are passed
1641 to the extrenal command in the environment as well and so could
1642 be used.
1643 In the login panel, press F1 to get a list of the available
1645 options that you can add after the username.
1646 Another option is "geom=WxH" or "geom=WxHxD" (or ge=). This only
1648 has an effect in FINDCREATEDISPLAY mode when a virtual X server
1649 such as Xvfb is going to be created. It sets the width and
1650 height of the new display, and optionally the color depth as
1651 well.
1652 You can also supply "gnome", "kde", "twm", "fvwm", "mwm",
1654 "dtwm", "wmaker", "xfce", "lxde", "enlightenment", "Xsession",
1655 or "failsafe" (same as "xterm") to have the created display use
1656 that mode for the user session.
1657 Specify "tag=..." to set the unique FD_TAG desktop session tag
1659 described below. Note: this option will be ignored if the
1660 FD_TAG env. var. is already set or if the viewer-side supplied
1661 value is not completely composed of alphanumeric or '_' or '-'
1662 characters.
1663 User preferences file: Instead of having the user type in
1665 geom=WxH,... etc. every time he logs in to find or create his X
1666 session, if you set FD_USERPREFS to a string that does not con‐
1667 tain the "/" character, then the user's home directory is
1668 prepended to that string and if the file exists its first line
1669 is read and appended to any options he supplied at the login:
1670 prompt. For example -env FD_USERPREFS=.x11vnc_create and the
1671 user put "geom=1600x1200" in his ~/.x11vnc_create file.
1672 To disable the option setting set the environment variable
1674 X11VNC_NO_UNIXPW_OPTS=1 before starting x11vnc. To set any
1675 other options, the user can use the gui (x11vnc -gui connect) or
1676 the remote control method (x11vnc -R opt:val) during his VNC
1677 session.
1678 So we see the combination of -display WAIT:cmd=... and -unixpw
1680 allows automatic pairing of an unix authenticated VNC user with
1681 his desktop. This could be very useful on SunRays and also any
1682 system where multiple users share a given machine. The user
1683 does not need to remember special ports or passwords set up for
1684 his desktop and VNC.
1685 A nice way to use WAIT:cmd=... is out of inetd(8) (it automati‐
1687 cally forks a new x11vnc for each user). You can have the
1688 x11vnc inetd spawned process run as, say, root or nobody. When
1689 run as root (for either inetd or display manager), you can also
1690 supply the option "-users unixpw=" to have the x11vnc process
1691 switch to the user as well. Note: there will be a 2nd SSL
1692 helper process that will not switch, but it is only encoding and
1693 decoding the encrypted stream at that point.
1694 BUILT-IN modes:
1696 -- Automatic Finding of User X Sessions --
1698 As a special case, WAIT:cmd=FINDDISPLAY will run a script that
1700 works on most Unixes to determine a user's DISPLAY variable and
1701 xauthority data (see who(1) ).
1702 NOTE: The option "-find" is an alias for this mode.
1704 To have this default script printed to stdout (e.g. for cus‐
1706 tomization) run with WAIT:cmd=FINDDISPLAY-print To have the
1707 script run to print what display it would find use "-finddpy" or
1708 WAIT:cmd=FINDDISPLAY-run
1709 The standard script runs xdpyinfo(1) run on potential displays.
1711 If your X server(s) have a login greeter that exclusively grabs
1712 the Xserver, then xdpyinfo blocks forever and this mode will not
1713 work. See www.karlrunge.com/x11vnc/faq.html#faq-display-manager
1714 for how to disable this for dtgreet on Solaris and possibly for
1715 other greeters.
1716 In -find/cmd=FINDDISPLAY mode, if you set FD_XDM=1, e.g. 'x11vnc
1718 -env FD_XDM=1 -find ...' and x11vnc is running as root (e.g.
1719 inetd) then it will try to find the XAUTHORITY file of a running
1720 XDM/GDM/KDM login greeter (i.e. no user has logged into an X
1721 session yet.)
1722 As another special case, WAIT:cmd=HTTPONCE will allow x11vnc to
1724 service one http request and then exit. This is usually done in
1725 -inetd mode to run on, say, port 5800 and allow the Java
1726 vncviewer to be downloaded by client web browsers. For example:
1727 5815 stream tcp nowait root /usr/sbin/tcpd /.../x11vnc \ -inetd
1729 -q -http_ssl -prog /.../x11vnc \ -display WAIT:cmd=HTTPONCE
1730 Where /.../x11vnc is the full path to x11vnc. It is used in the
1732 Apache SSL-portal example (see FAQ).
1733 In this mode you can set X11VNC_SKIP_DISPLAY to a comma sepa‐
1735 rated list of displays (e.g. ":0,:1") to ignore in the finding
1736 process. The ":" is optional. Ranges n-m e.g. 0-20 can also be
1737 supplied. This string can also be set by the connecting user via
1738 "nd=" using "+" instead of "," If "nd=all" or you set
1739 X11VNC_SKIP_DISPLAY=all then all display finding fails as if you
1740 set X11VNC_FINDDISPLAY_ALWAYS_FAILS=1 (below.)
1741 On some systems lsof(1) can be very slow. Set the env. var.
1743 FIND_DISPLAY_NO_LSOF=1 to skip using lsof to try to find the
1744 Linux VT the X server is running on. set FIND_DIS‐
1745 PLAY_NO_VT_FIND=1 to avoid looking at all.
1746 -- Automatic Creation of User X Sessions --
1748 An interesting option is WAIT:cmd=FINDCREATEDISPLAY that is like
1750 FINDDISPLAY in that is uses the same method to find an existing
1751 display. However, if it does not find one it will try to
1752 *start* up an X server session for the user. This is the only
1753 time x11vnc tries to actually start up an X server.
1754 NOTE: The option "-create" is an alias for this mode.
1756 It will start looking for an open display number at :20 Override
1758 via X11VNC_CREATE_STARTING_DISPLAY_NUMBER=n By default 80 X dis‐
1759 plays are allowed (i.e. going to :99) Override via X11VNC_CRE‐
1760 ATE_MAX_DISPLAYS=n
1761 For its heuristics, the create display script sets LC_ALL=C so
1763 that command output is uniform. By default it will try to
1764 restore LC_ALL right before starting the user session. However,
1765 if you don't mind it keeping LC_ALL=C set the env. var.:
1766 X11VNC_CREATE_LC_ALL_C_OK=1
1767 By default FINDCREATEDISPLAY will try Xvfb and then Xdummy:
1769 The Xdummy wrapper is part of the x11vnc source code
1771 (x11vnc/misc/Xdummy) It should be available in PATH and have
1772 run "Xdummy -install" once to create the shared library. Xdummy
1773 only works on Linux. As of 12/2009 it no longer needs to be run
1774 as root, and the default is to not run as root. In some circum‐
1775 stances permissions may require running it as root, in these
1776 cases specify FD_XDUMMY_RUN_AS_ROOT=1, this is the same as sup‐
1777 plying -root to the Xdummy cmdline.
1778 Xvfb is available on most platforms and does not require root.
1780 An advantage of Xdummy over Xvfb is that Xdummy supports RANDR
1782 dynamic screen resizing.
1783 When x11vnc exits (i.e. user disconnects) the X server session
1785 stays running in the background. The FINDDISPLAY will find it
1786 directly next time. The user must exit the X session in the
1787 usual way for it to terminate (or kill the X server process if
1788 all else fails).
1789 To troubleshoot the FINDCREATEDISPLAY mechanism, set the follow‐
1791 ing env. var. to an output log file, e.g -env CREATE_DIS‐
1792 PLAY_OUTPUT=/tmp/mydebug.txt
1793 So this is a somewhat odd mode for x11vnc in that it will start
1795 up and poll virtual X servers! This can be used from, say,
1796 inetd(8) to provide a means of definitely getting a desktop
1797 (either real or virtual) on the machine. E.g. a desktop ser‐
1798 vice:
1799 5900 stream tcp nowait root /usr/sbin/tcpd /.../x11vnc -inetd -q
1801 -http -ssl SAVE -unixpw -users unixpw=\ -passwd secret -prog
1802 /.../x11vnc \ -display WAIT:cmd=FINDCREATEDISPLAY
1803 Where /.../x11vnc is the full path to x11vnc.
1805 See the -svc/-service option alias above.
1807 If for some reason you do not want x11vnc to ever try to find an
1809 existing display set the env. var X11VNC_FINDDIS‐
1810 PLAY_ALWAYS_FAILS=1 (also -env ...) This is the same as setting
1811 X11VNC_SKIP_DISPLAY=all or supplying "nd=all" after "username:"
1812 Use WAIT:cmd=FINDCREATEDISPLAY-print to print out the script
1814 that is used for this.
1815 You can specify the preferred X server order via e.g.,
1817 WAIT:cmd=FINDCREATEDISPLAY-Xdummy,Xvfb,X and/or leave out ones
1818 you do not want. The the case "X" means try to start up a real,
1819 hardware X server using xinit(1) or startx(1). If there is
1820 already an X server running the X case may only work on Linux
1821 (see startx(1) ).
1822 "Xvnc" will start up a VNC X server (real- or tight-vnc, e.g.
1824 use if Xvfb is not available). "Xsrv" will start up the server
1825 program in the variable "FD_XSRV" if it is non-empty. You can
1826 make this be a wrapper script if you like (it must handle :N,
1827 -geometry, and -depth and other X server options).
1828 You can set the environment variable FD_GEOM (or X11VNC_CRE‐
1830 ATE_GEOM) to WxH or WxHxD to set the width and height and
1831 optionally the color depth of the created display. You can also
1832 set FD_SESS to be the session (short name of the windowmanager:
1833 kde, gnome, twm, failsafe, etc.). FD_OPTS contains extra options
1834 to pass to the X server. You can also set FD_PROG to be the full
1835 path to the session/windowmanager program.
1836 More FD tricks: FD_CUPS=port or FD_CUPS=host:port will set the
1838 cups printing environment. Similarly for FD_ESD=port or
1839 FD_ESD=host:port for esddsp sound redirection. Set FD_EXTRA to
1840 a command to be run a few seconds after the X server starts up.
1841 Set FD_TAG to be a unique name for the session, it is set as an
1842 X property, that makes FINDDISPLAY only find sessions with that
1843 tag value.
1844 Set FD_XDMCP_IF to the network interface that the display man‐
1846 ager is running on; default is 'localhost' but you may need to
1847 set it to '::1' on some IPv6 only systems or misconfigured dis‐
1848 play managers.
1849 Set FD_NOLISTEN to override the default '-nolisten tcp'
1851 If you want the FINDCREATEDISPLAY session to contact an XDMCP
1853 login manager (xdm/gdm/kdm) on the same machine, then use
1854 "Xvfb.xdmcp" instead of "Xvfb", etc. The user will have to sup‐
1855 ply his username and password one more time (but he gets to
1856 select his desktop type so that can be useful). For this to
1857 work, you will need to enable localhost XDMCP (udp port 177) for
1858 the display manager. This seems to be:
1859 for gdm in gdm.conf: Enable=true in section [xdmcp] for kdm in
1861 kdmrc: Enable=true in section [Xdmcp] for xdm in xdm-con‐
1862 fig: DisplayManager.requestPort: 177
1863 See the shorthand options above "-svc", "-xdmsvc" and
1865 "-sshxdmsvc" that specify the above options for some useful
1866 cases.
1867 If you set the env. var WAITBG=1 x11vnc will go into the back‐
1869 ground once listening in wait mode.
1870 Another special mode is FINDCREATEDISPLAY-Xvnc.redirect, (or
1872 FINDDISPLAY-Xvnc.redirect). In this case it will start up Xvnc
1873 as above if needed, but instead of polling it in its normal way,
1874 it simply does a socket redirection of the connected VNC viewer
1875 to the Xvnc.
1876 So in Xvnc.redirect x11vnc does no VNC but merely transfers the
1878 data back and forth. This should be faster then x11vnc's
1879 polling method, but not as fast as connecting directly to the
1880 Xvnc with the VNC Viewer. The idea here is to take advantage of
1881 x11vnc's display finding/creating scheme, SSL, and perhaps a few
1882 others. Most of x11vnc's options do not apply in this mode.
1883 Xvnc.redirect should also work for the vnc.so X server module
1885 for the h/w display however it will work only for finding the
1886 display and the user must already be logged into the X console.
1887 -vencrypt mode
1889 The VeNCrypt extension to the VNC protocol allows encrypted
1891 SSL/TLS connections. If the -ssl mode is enabled, then VeNCrypt
1892 is enabled as well BY DEFAULT (they both use a SSL/TLS tunnel,
1893 only the protocol handshake is a little different.)
1894 To control when and how VeNCrypt is used, specify the mode
1896 string. If mode is "never", then VeNCrypt is not used. If mode
1897 is "support" (the default) then VeNCrypt is supported. If mode
1898 is "only", then the similar and older ANONTLS protocol is not
1899 simultaneously supported. x11vnc's normal SSL mode (vncs://)
1900 will be supported under -ssl unless you set mode to "force".
1901 If mode is prefixed with "nodh:", then Diffie Hellman anonymous
1903 key exchange is disabled. If mode is prefixed with "nox509:",
1904 then X509 key exchange is disabled.
1905 To disable all Anonymous Diffie-Hellman access (susceptible to
1907 Man-In-The-Middle attack) you will need to supply "-vencrypt
1908 nodh:support -anontls never" or "-vencrypt nodh:only"
1909 If mode is prefixed with "newdh:", then new Diffie Hellman
1911 parameters are generated for each connection (this can be time
1912 consuming: 1-60 secs; see -dhparams below for a faster way)
1913 rather than using the fixed values in the program. Using fixed,
1914 publicly known values is not known to be a security problem.
1915 This setting applies to ANONTLS as well.
1916 Long example: -vencrypt newdh:nox509:support
1918 Also, if mode is prefixed with "plain:", then if -unixpw mode is
1920 active the VeNCrypt "*Plain" username+passwd method is enabled
1921 for Unix logins. Otherwise in -unixpw mode the normal login
1922 panel is provided.
1923 You *MUST* supply the -ssl option for VeNCrypt to be active.
1925 The -vencrypt option only fine-tunes its operation.
1926 -anontls mode
1928 The ANONTLS extension to the VNC protocol allows encrypted
1930 SSL/TLS connections. If the -ssl mode is enabled, then ANONTLS
1931 is enabled as well BY DEFAULT (they both use a SSL/TLS tunnel,
1932 only the protocol handshake is a little different.)
1933 ANONTLS is an older SSL/TLS mode introduced by vino.
1935 It is referred to as 'TLS' for its registered VNC security-type
1937 name, but we use the more descriptive ´ANONTLS' here because it
1938 provides only Anonymous Diffie-Hellman encrypted connections,
1939 and hence no possibility for certificate authentication.
1940 To control when and how ANONTLS is used, specify the mode
1942 string. If mode is "never", then ANONTLS is not used. If mode
1943 is "support" (the default) then ANONTLS is supported. If mode
1944 is "only", then the similar VeNCrypt protocol is not simultane‐
1945 ously supported. x11vnc's normal SSL mode (vncs://) will be
1946 supported under -ssl unless you set mode to "force".
1947 If mode is prefixed with "newdh:", then new Diffie Hellman
1949 parameters are generated for each connection (this can be time
1950 consuming: 1-60 secs; see -dhparams below for a faster way)
1951 rather than using the fixed values in the program. Using fixed,
1952 publicly known values is not known to be a security problem.
1953 This setting applies to VeNCrypt as well. See the description
1954 of "plain:" under -vencrypt.
1955 Long example: -anontls newdh:plain:support
1957 You *MUST* supply the -ssl option for ANONTLS to be active. The
1959 -anontls option only fine-tunes its operation.
1960 -sslonly
1962 Same as: "-vencrypt never -anontls never" i.e. it disables the
1964 VeNCrypt and ANONTLS encryption methods and only allows standard
1965 SSL tunneling. You must also supply the -ssl ... option (see
1966 below.)
1967 -dhparams file
1969 For some operations a set of Diffie Hellman parameters (prime
1971 and generator) is needed. If so, use the parameters in file. In
1972 particular, the VeNCrypt and ANONTLS anonymous DH mode need
1973 them. By default a fixed set is used. If you do not want to do
1974 that you can specify "newdh:" to the -vencrypt and -anontls
1975 options to generate a new set each session. If that is too slow
1976 for you, use -dhparams file to a set you created manually via
1977 "openssl dhparam -out file 1024"
1978 -nossl
1980 Disable the -ssl option (see below). Since -ssl is off by
1982 default -nossl would only be used on the commandline to unset
1983 any *earlier* -ssl option (or -svc...)
1984 -ssl [pem]
1986 Use the openssl library (www.openssl.org) to provide a built-in
1988 encrypted SSL/TLS tunnel between VNC viewers and x11vnc. This
1989 requires libssl support to be compiled into x11vnc at build
1990 time. If x11vnc is not built with libssl support it will exit
1991 immediately when -ssl is prescribed. See the -stunnel option
1992 below for an alternative.
1993 The VNC Viewer-side needs to support SSL/TLS as well. See this
1995 URL and also the discussion below for ideas on how to enable SSL
1996 support for the viewer: http://www.karl‐
1997 runge.com/x11vnc/faq.html#faq-ssl-tun nel-viewers . x11vnc pro‐
1998 vides an SSL enabled Java viewer applet in the classes/ssl
1999 directory (-http or -httpdir options.) The SSVNC viewer package
2000 supports SSL tunnels too.
2001 If the VNC Viewer supports VeNCrypt or ANONTLS (vino's encryp‐
2003 tion mode) they are also supported by the -ssl mode (see the
2004 -vencrypt and -anontls options for more info; use -sslonly to
2005 disable both of them.)
2006 Use "-ssl /path/to/mycert.pem" to specify an SSL certificate
2008 file in PEM format to use to identify and provide a key for this
2009 server. See openssl(1) for more info about PEMs and the
2010 -sslGenCert and "-ssl SAVE" options below for how to create
2011 them.
2012 The connecting VNC viewer SSL tunnel can (at its option) authen‐
2014 ticate this server if it has the public key part of the certifi‐
2015 cate (or a common certificate authority, CA, is a more sophisti‐
2016 cated way to verify this server's cert, see -sslGenCA below).
2017 This authentication is done to prevent Man-In-The-Middle
2018 attacks. Otherwise, if the VNC viewer simply accepts this
2019 server's key WITHOUT verification, the traffic is protected from
2020 passive sniffing on the network, but *NOT* from Man-In-The-Mid‐
2021 dle attacks. There are hacker tools like dsniff/webmitm and cain
2022 that implement SSL Man-In-The-Middle attacks.
2023 If [pem] is empty or the string "SAVE" then the openssl(1) com‐
2025 mand must be available to generate the certificate the first
2026 time. A self-signed certificate is generated (see -sslGenCA and
2027 -sslGenCert for use of a Certificate Authority.) It will be
2028 saved to the file ~/.vnc/certs/server.pem. On subsequent calls
2029 if that file already exists it will be used directly.
2030 Use "SAVE_NOPROMPT" to avoid being prompted to protect the gen‐
2032 erated key with a passphrase. However in -inetd and -bg modes
2033 there will be no prompting for a passphrase in either case.
2034 If [pem] is "SAVE_PROMPT" the server.pem certificate will be
2036 created based on your answers to its prompts for all info such
2037 as OrganizationalName, CommonName, etc.
2038 Use "SAVE-<string>" and "SAVE_PROMPT-<string>" to refer to the
2040 file ~/.vnc/certs/server-<string>.pem instead (it will be gener‐
2041 ated if it does not already exist). E.g. "SAVE-charlie" will
2042 store to the file ~/.vnc/certs/server-charlie.pem
2043 Examples: x11vnc -ssl SAVE -display :0 ... x11vnc -ssl SAVE-
2045 someother -display :0 ...
2046 If [pem] is "TMP" and the openssl(1) utility command exists in
2048 PATH, then a temporary, self-signed certificate will be gener‐
2049 ated for this session. If openssl(1) cannot be used to generate
2050 a temporary certificate x11vnc exits immediately. The temporary
2051 cert will be discarded when x11vnc exits.
2052 If successful in using openssl(1) to generate a temporary cer‐
2054 tificate in "SAVE" or "TMP" creation modes, the public part of
2055 it will be displayed to stderr (e.g. one could copy it to the
2056 client-side to provide authentication of the server to VNC view‐
2057 ers.)
2058 NOTE: In "TMP" mode, unless you safely copy the public part of
2060 the temporary Cert to the viewer for authenticate *every time*
2061 (unlikely...), then only passive sniffing attacks are prevented
2062 and you are still open to Man-In-The-Middle attacks. This is
2063 why the default "SAVE" mode is preferred (and more sophisticated
2064 CA mode too). Only with saved keys AND the VNC viewer authenti‐
2065 cating them (via the public certificate), are Man-In-The-Middle
2066 attacks prevented.
2067 If [pem] is "ANON" then the Diffie-Hellman anonymous key
2069 exchange method is used. In this mode there are *no* SSL cer‐
2070 tificates and so it is not possible to authenticate either the
2071 VNC server or VNC client. Thus only passive network sniffing
2072 attacks are avoided: the "ANON" method is susceptible to Man-In-
2073 The-Middle attacks. "ANON" is not recommended; instead use a
2074 SSL PEM you created or the default "SAVE" method.
2075 See -ssldir below to use a directory besides the default
2077 ~/.vnc/certs
2078 If your x11vnc binary was not compiled with OpenSSL library sup‐
2080 port, use of the -ssl option will induce an immediate failure
2081 and exit. For such binaries, consider using the -stunnel option
2082 for SSL encrypted connections.
2083 Misc Info: In temporary cert creation mode "TMP", set the env.
2085 var. X11VNC_SHOW_TMP_PEM=1 to have x11vnc print out the entire
2086 certificate, including the PRIVATE KEY part, to stderr. There
2087 are better ways to get/save this info. See "SAVE" above and
2088 "-sslGenCert" below.
2089 -ssltimeout n
2091 Set SSL read timeout to n seconds. In some situations (i.e. an
2093 iconified viewer in Windows) the viewer stops talking and the
2094 connection is dropped after the default timeout (25s for about
2095 the first minute, 43200s later). Set to zero to poll forever.
2096 Set to a negative value to use the builtin setting.
2097 Note that this value does NOT apply to the *initial* ssl init
2099 connection. The default timeout for that is 20sec. Use -env
2100 SSL_INIT_TIMEOUT=n to modify it.
2101 -sslnofail
2103 Exit at the first SSL connection failure. Useful when scripting
2105 SSL connections (e.g. x11vnc is started via ssh) and you do not
2106 want x11vnc waiting around for more connections, tying up ports,
2107 etc.
2108 -ssldir dir
2110 Use dir as an alternate ssl certificate and key management
2112 toplevel directory. The default is ~/.vnc/certs
2113 This directory is used to store server and other certificates
2115 and keys and also other materials. E.g. in the simplest case,
2116 "-ssl SAVE" will store the x11vnc server cert in dir/server.pem
2117 Use of alternate directories via -ssldir allows you to manage
2119 multiple VNC Certificate Authority (CA) keys. Another use is if
2120 ~/.vnc/cert is on an NFS share you might want your certificates
2121 and keys to be on a local filesystem to prevent network snooping
2122 (for example -ssldir /var/lib/x11vnc-certs).
2123 -ssldir affects nearly all of the other -ssl* options, e.g. -ssl
2125 SAVE, -sslGenCert, etc..
2126 -sslverify path
2128 For either of the -ssl or -stunnel modes, use path to provide
2130 certificates to authenticate incoming VNC *Client* connections
2131 (normally only the server is authenticated in SSL.) This can be
2132 used as a method to replace standard password authentication of
2133 clients.
2134 If path is a directory it contains the client (or CA) certifi‐
2136 cates in separate files. If path is a file, it contains one or
2137 more certificates. See special tokens below. These correspond
2138 to the "CApath = dir" and "CAfile = file" stunnel options. See
2139 the stunnel(8) manpage for details.
2140 Examples: x11vnc -ssl -sslverify ~/my.crt x11vnc -ssl -sslverify
2142 ~/my_pem_dir/
2143 Note that if path is a directory, it must contain the certs in
2145 separate files named like <HASH>.0, where the value of <HASH> is
2146 found by running the command "openssl x509 -hash -noout -in
2147 file.crt". Evidently one uses <HASH>.1 if there is a colli‐
2148 sion...
2149 The the key-management utility "-sslCertInfo HASHON" and
2151 "-sslCertInfo HASHOFF" will create/delete these hashes for you
2152 automatically (via symlink) in the HASH subdirs it manages.
2153 Then you can point -sslverify to the HASH subdir.
2154 Special tokens: in -ssl mode, if path is not a file or a direc‐
2156 tory, it is taken as a comma separated list of tokens that are
2157 interpreted as follows:
2158 If a token is "CA" that means load the CA/cacert.pem file from
2160 the ssl directory. If a token is "clients" then all the files
2161 clients/*.crt in the ssl directory are loaded. Otherwise the
2162 file clients/token.crt is attempted to be loaded. As a kludge,
2163 use a token like ../server-foo to load a server cert if you find
2164 that necessary.
2165 Use -ssldir to use a directory different from the ~/.vnc/certs
2167 default.
2168 Note that if the "CA" cert is loaded you do not need to load any
2170 of the certs that have been signed by it. You will need to load
2171 any additional self-signed certs however.
2172 Examples: x11vnc -ssl -sslverify CA x11vnc -ssl -sslverify
2174 self:fred,self:jim x11vnc -ssl -sslverify CA,clients
2175 Usually "-sslverify CA" is the most effective. See the
2177 -sslGenCA and -sslGenCert options below for how to set up and
2178 manage the CA framework.
2179 Note that if the Client's (vncviewer) certificate has been
2181 signed by a well-known CA then the CA's certificate may already
2182 be installed on the system. So, for example, on a debian based
2183 system one could use: -sslverify /etc/ssl/certs.
2184 NOTE: the following utilities, -sslGenCA, -sslGenCert,
2186 -sslEncKey, -sslCertInfo, and -sslCRL are provided for complete‐
2187 ness, but for casual usage they are overkill.
2188 They provide VNC Certificate Authority (CA) key creation and
2190 server / client key generation and signing. So they provide a
2191 basic Public Key management framework for VNC-ing with x11vnc.
2192 (note that they require openssl(1) be installed on the system)
2193 However, the simplest usage mode, "-ssl TMP" (where x11vnc auto‐
2195 matically generates its own, self-signed, temporary key and the
2196 VNC viewers always accept it, e.g. accepting via a dialog box)
2197 is probably safe enough for most scenarios. CA management is
2198 not needed.
2199 To protect against Man-In-The-Middle attacks the "TMP" mode can
2201 be improved by using "-ssl SAVE" (same as "-ssl", i.e. the
2202 default) to have x11vnc create a longer term self-signed cer‐
2203 tificate, and then (safely) copy the corresponding public key
2204 cert to the desired client machines (care must be taken the pri‐
2205 vate key part is not stolen; you will be prompted for a
2206 passphrase).
2207 So keep in mind no CA key creation or management (-sslGenCA and
2209 -sslGenCert) is needed for either of the above two common usage
2210 modes.
2211 One might want to use -sslGenCA and -sslGenCert if you had a
2213 large number of VNC client and server workstations. That way
2214 the administrator could generate a single CA key with -sslGenCA
2215 and distribute its certificate part to all of the workstations.
2216 Next, he could create signed VNC server keys (-sslGenCert server
2218 ...) for each workstation or user that then x11vnc would use to
2219 authenticate itself to any VNC client that has the CA cert.
2220 Optionally, the admin could also make it so the VNC clients
2222 themselves are authenticated to x11vnc (-sslGenCert client ...)
2223 For this -sslverify would be pointed to the CA cert (and/or
2224 self-signed certs).
2225 x11vnc will be able to use all of these cert and key files. On
2227 the VNC client side, they will need to be "imported" somehow.
2228 Web browsers have "Manage Certificates" actions as does the Java
2229 applet plugin Control Panel. stunnel can also use these files
2230 (see the ss_vncviewer example script in the FAQ and SSVNC.)
2231 -sslCRL path
2233 Set the Certificate Revocation Lists (CRL) to path. This set‐
2235 ting applies for both -ssl and -stunnel modes.
2236 If path is a file, the file contains one or more CRLs in PEM
2238 format. If path is a directory, it contains hash named files of
2239 CRLs in the usual OpenSSL manner. See the OpenSSL and stun‐
2240 nel(8) documentation for more info.
2241 This option only applies if -sslverify has been supplied: it
2243 checks for revocation along the certificate chain used to verify
2244 the VNC client. The -sslCRL setting will be ignored when
2245 -sslverify is not specified.
2246 Note that if a CRL's expiration date has passed, all SSL connec‐
2248 tions will fail regardless of if they are related to the subject
2249 of the CRL or not.
2250 Only rarely will one's x11vnc -ssl infrastructure be so large
2252 that this option would be useful (since normally maintaining the
2253 contents of the -sslverify file or directory should be enough.)
2254 However, when using x11vnc with a Certificate Authority (see
2255 -sslGenCA) to authenticate Clients via SSL/TLS, the -sslCRL
2256 option can be useful to revoke users' certs whose private SSL
2257 keys were lost or stolen (e.g. laptop.) This way a new CA
2258 cert+key does not need to be created and new signed client keys
2259 generated and distributed to all users.
2260 To create a CRL file with revoked certificates the commands
2262 'openssl ca -revoke ...' and 'openssl ca -gencrl ...' are use‐
2263 ful. (Run them in ~/.vnc/certs)
2264 -sslGenCA [dir]
2266 Generate your own Certificate Authority private key, certifi‐
2268 cate, and other files in directory [dir]. x11vnc then exits.
2269 If [dir] is not supplied, a -ssldir setting is used, or other‐
2271 wise ~/.vnc/certs is used.
2272 This command also creates directories where server and client
2274 certs and keys will be stored. The openssl(1) program must be
2275 installed on the system and available in PATH.
2276 After the CA files and directories are created the x11vnc com‐
2278 mand exits; the VNC server is not run.
2279 You will be prompted for information to put into the CA certifi‐
2281 cate. The info does not have to be accurate just as long as
2282 clients accept the cert for VNC connections. You will also need
2283 to supply a passphrase of at least 4 characters for the CA pri‐
2284 vate key.
2285 Once you have generated the CA you can distribute its certifi‐
2287 cate part, [dir]/CA/cacert.pem, to other workstations where VNC
2288 viewers will be run. One will need to "import" this certificate
2289 in the applications, e.g. Web browser, Java applet plugin, stun‐
2290 nel, etc. Next, you can create and sign keys using the CA with
2291 the -sslGenCert option below.
2292 Examples: x11vnc -sslGenCA x11vnc -sslGenCA ~/myCAdir x11vnc
2294 -ssldir ~/myCAdir -sslGenCA
2295 (the last two lines are equivalent)
2297 -sslGenCert type name
2299 Generate a VNC server or client certificate and private key pair
2301 signed by the CA created previously with -sslGenCA. The
2302 openssl(1) program must be installed on the system and available
2303 in PATH.
2304 After the Certificate is generated x11vnc exits; the VNC server
2306 is not run.
2307 The type of key to be generated is the string type. It is
2309 either "server" (i.e. for use by x11vnc) or "client" (for a VNC
2310 viewer). Note that typically only "server" is used: the VNC
2311 clients authenticate themselves by a non-public-key method (e.g.
2312 VNC or unix password). type is required.
2313 An arbitrary default name you want to associate with the key is
2315 supplied by the name string. You can change it at the various
2316 prompts when creating the key. name is optional.
2317 If name is left blank for clients keys then "nobody" is used.
2319 If left blank for server keys, then the primary server key:
2320 "server.pem" is created (this is the saved one referenced by
2321 "-ssl SAVE" when the server is started)
2322 If name begins with the string "self:" then a self-signed cer‐
2324 tificate is created instead of one signed by your CA key.
2325 If name begins with the string "req:" then only a key (.key) and
2327 a certificate signing *request* (.req) are generated. You can
2328 then send the .req file to an external CA (even a professional
2329 one, e.g. Thawte) and then combine the .key and the received
2330 cert into the .pem file with the same basename.
2331 The distinction between "server" and "client" is simply the
2333 choice of output filenames and sub-directory. This makes it so
2334 the -ssl SAVE-name option can easily pick up the x11vnc PEM file
2335 this option generates. And similarly makes it easy for the
2336 -sslverify option to pick up your client certs.
2337 There is nothing special about the filename or directory loca‐
2339 tion of either the "server" and "client" certs. You can rename
2340 the files or move them to wherever you like.
2341 Precede this option with -ssldir [dir] to use a directory other
2343 than the default ~/.vnc/certs You will need to run -sslGenCA on
2344 that directory first before doing any -sslGenCert key creation.
2345 Note you cannot recreate a cert with exactly the same distigu‐
2347 ished name (DN) as an existing one. To do so, you will need to
2348 edit the [dir]/CA/index.txt file to delete the line.
2349 Similar to -sslGenCA, you will be prompted to fill in some
2351 information that will be recorded in the certificate when it is
2352 created.
2353 Tip: if you know the fully-qualified hostname other people will
2355 be connecting to, you can use that as the CommonName "CN" to
2356 avoid some applications (e.g. web browsers and java plugin) com‐
2357 plaining that it does not match the hostname.
2358 You will also need to supply the CA private key passphrase to
2360 unlock the private key created from -sslGenCA. This private key
2361 is used to sign the server or client certificate.
2362 The "server" certs can be used by x11vnc directly by pointing to
2364 them via the -ssl [pem] option. The default file will be
2365 ~/.vnc/certs/server.pem. This one would be used by simply typ‐
2366 ing -ssl SAVE. The pem file contains both the certificate and
2367 the private key. server.crt file contains the cert only.
2368 The "client" cert + private key file will need to be copied and
2370 imported into the VNC viewer side applications (Web browser,
2371 Java plugin, stunnel, etc.) Once that is done you can delete
2372 the "client" private key file on this machine since it is only
2373 needed on the VNC viewer side. The, e.g.
2374 ~/.vnc/certs/clients/<name>.pem contains both the cert and pri‐
2375 vate key. The <name>.crt contains the certificate only.
2376 NOTE: It is very important to know one should generate new keys
2378 with a passphrase. Otherwise if an untrusted user steals the
2379 key file he could use it to masquerade as the x11vnc server (or
2380 VNC viewer client). You will be prompted whether to encrypt the
2381 key with a passphrase or not. It is recommended that you do.
2382 One inconvenience to a passphrase is that it must be typed in
2383 EVERY time x11vnc or the client app is started up.
2384 Examples:
2386 x11vnc -sslGenCert server x11vnc -ssl SAVE -display :0 ...
2388 and then on viewer using ss_vncviewer stunnel wrapper (see the
2390 FAQ): ss_vncviewer -verify ./cacert.crt hostname:0
2391 (this assumes the cacert.crt cert from -sslGenCA was safely
2393 copied to the VNC viewer machine where ss_vncviewer is run)
2394 Example using a name:
2396 x11vnc -sslGenCert server charlie x11vnc -ssl SAVE-charlie -dis‐
2398 play :0 ...
2399 Example for a client certificate (rarely used):
2401 x11vnc -sslGenCert client roger scp
2403 ~/.vnc/certs/clients/roger.pem somehost:. rm
2404 ~/.vnc/certs/clients/roger.pem
2405 x11vnc is then started with the option -sslverify
2407 ~/.vnc/certs/clients/roger.crt (or simply -sslverify roger), and
2408 on the viewer user on somehost could do for example:
2409 ss_vncviewer -mycert ./roger.pem hostname:0
2411 If you set the env. var REQ_ARGS='...' it will be passed to
2413 openssl req(1). A common use would be REQ_ARGS='-days 1095' to
2414 bump up the expiration date (3 years in this case).
2415 -sslEncKey pem
2417 Utility to encrypt an existing PEM file with a passphrase you
2419 supply when prompted. For that key to be used (e.g. by x11vnc)
2420 the passphrase must be supplied each time.
2421 The "SAVE" notation described under -ssl applies as well. (pre‐
2423 cede this option with -ssldir [dir] to refer a directory besides
2424 the default ~/.vnc/certs)
2425 The openssl(1) program must be installed on the system and
2427 available in PATH. After the Key file is encrypted the x11vnc
2428 command exits; the VNC server is not run.
2429 Examples: x11vnc -sslEncKey /path/to/foo.pem x11vnc -sslEncKey
2431 SAVE x11vnc -sslEncKey SAVE-charlie
2432 -sslCertInfo pem
2434 Prints out information about an existing PEM file. In addition
2436 the public certificate is also printed. The openssl(1) program
2437 must be in PATH. Basically the command "openssl x509 -text" is
2438 run on the pem.
2439 After the info is printed the x11vnc command exits; the VNC
2441 server is not run.
2442 The "SAVE" notation described under -ssl applies as well.
2444 Using "LIST" will give a list of all certs being managed (in
2446 the ~/.vnc/certs dir, use -ssldir to refer to another dir).
2447 "ALL" will print out the info for every managed key (this can be
2448 very long). Giving a client or server cert shortname will also
2449 try a lookup (e.g. -sslCertInfo charlie). Use "LISTL" or "LL"
2450 for a long (ls -l style) listing.
2451 Using "HASHON" will create subdirs [dir]/HASH and [dir]/HASH
2453 with OpenSSL hash filenames (e.g. 0d5fbbf1.0) symlinks pointing
2454 up to the corresponding *.crt file. ([dir] is ~/.vnc/certs or
2455 one given by -ssldir.) This is a useful way for other OpenSSL
2456 applications (e.g. stunnel) to access all of the certs without
2457 having to concatenate them. x11vnc will not use them unless you
2458 specifically reference them. "HASHOFF" removes these HASH sub‐
2459 dirs.
2460 The LIST, LISTL, LL, ALL, HASHON, HASHOFF words can also be low‐
2462 ercase, e.g. "list".
2463 -sslDelCert pem
2465 Prompts you to delete all .crt .pem .key .req files associated
2467 with [pem]. x11vnc then exits. "SAVE" and lookups as in
2468 -sslCertInfo apply as well.
2469 -sslScripts
2471 Prints out both the 'genCA' and 'genCert' x11vnc openssl wrapper
2473 scripts for you to examine, modify, etc. The scripts are
2474 printed to stdout and then the x11vnc program exits.
2475 -stunnel [pem]
2477 Use the stunnel(8) (stunnel.mirt.net) to provide an encrypted
2479 SSL tunnel between viewers and x11vnc.
2480 This external tunnel method was implemented prior to the inte‐
2482 grated -ssl encryption described above. It still works well and
2483 avoids the requirement of linking with the OpenSSL libraries.
2484 This mode requires stunnel to be installed on the system and
2485 available via PATH (n.b. stunnel is often installed in sbin
2486 directories). Version 4.x of stunnel is assumed (but see -stun‐
2487 nel3 below.)
2488 [pem] is optional, use "-stunnel /path/to/stunnel.pem" to spec‐
2490 ify a PEM certificate file to pass to stunnel. See the -ssl
2491 option for more info on certificate files.
2492 Whether or not your stunnel has its own certificate depends on
2494 your stunnel configuration; stunnel often generates one at
2495 install time. See your stunnel documentation for details. In
2496 any event, if you want to use this certificate you must supply
2497 the full path to it as [pem]. Note: the file may only be read‐
2498 able by root.
2499 [pem] may also be the special strings "TMP", "SAVE", and
2501 "SAVE..." as described in the -ssl option. If [pem] is not sup‐
2502 plied, "SAVE" is assumed.
2503 Note that the VeNCrypt, ANONTLS, and "ANON" modes are not sup‐
2505 ported in -stunnel mode.
2506 stunnel is started up as a child process of x11vnc and any SSL
2508 connections stunnel receives are decrypted and sent to x11vnc
2509 over a local socket. The strings "The SSL VNC desktop is ..."
2510 and "SSLPORT=..." are printed out at startup to indicate this.
2511 The -localhost option is enforced by default to avoid people
2513 routing around the SSL channel. Use -env STUNNEL_DISABLE_LOCAL‐
2514 HOST=1 to disable this security requirement.
2515 Set -env STUNNEL_DEBUG=1 for more debugging printout.
2517 Set -env STUNNEL_PROG=xxx to the full path of stunnel program
2519 you want to be used (e.g. /usr/bin/stunnel4).
2520 Set -env STUNNEL_LISTEN=xxx to the address of the network inter‐
2522 face to listen on (the default is to listen on all interfaces),
2523 e.g. STUNNEL_LISTEN=192.168.1.100.
2524 A simple way to add IPv6 support is STUNNEL_LISTEN=::
2526 Your VNC viewer will also need to be able to connect via SSL.
2528 Unfortunately not too many do this. See the information about
2529 SSL viewers under the -ssl option. The x11vnc project's SSVNC
2530 is an option.
2531 Also, in the x11vnc distribution, patched TightVNC and UltraVNC
2533 Java applet jar files are provided in the classes/ssl directory
2534 that do SSL connections. Enable serving them with the -http,
2535 -http_ssl, or -httpdir (see the option descriptions for more
2536 info.)
2537 Note that for the Java viewer applet usage the "?PORT=xxxx" in
2539 the various URLs printed at startup will need to be supplied to
2540 the web browser to connect properly.
2541 Currently the automatic "single port" HTTPS mode of -ssl is not
2543 fully supported in -stunnel mode. However, it can be emulated
2544 via:
2545 % x11vnc -stunnel -http_ssl -http_oneport ...
2547 In general, it is also not too difficult to set up an stunnel or
2549 other SSL tunnel on the viewer side. A simple example on Unix
2550 using stunnel 3.x is:
2551 % stunnel -c -d localhost:5901 -r remotehost:5900 % vncviewer
2553 localhost:1
2554 For Windows, stunnel has been ported to it and there are proba‐
2556 bly other such tools available. See the FAQ and SSVNC for more
2557 examples.
2558 -stunnel3 [pem]
2560 Use version 3.x stunnel command line syntax instead of version
2562 4.x. The -http/-httpdir Java applet serving is currently not
2563 available in this mode.
2564 -enc cipher:keyfile
2566 Use symmetric encryption with cipher "cipher" and secret key
2568 data in "keyfile". If keyfile is pw=<string> then "string" is
2569 used as the key data.
2570 NOTE: It is recommended that you use SSL via the -ssl option
2572 instead of this option because SSL is well understood and takes
2573 great care to establish unique session keys and is more compati‐
2574 ble with other software. Use this option if you do not want to
2575 deal with SSL certificates for authentication and do not want to
2576 use SSH but want some encryption for your VNC session. Or if
2577 you must interface with a symmetric key tunnel that you do not
2578 have control over.
2579 Note that this mode will NOT work with the UltraVNC DSM plugins
2581 because they alter the RFB protocol in addition to tunnelling
2582 with the symmetric cipher (an unfortunate choice of implementa‐
2583 tion...)
2584 cipher can be one of: arc4, aesv2, aes-cfb, blowfish, aes256,
2586 or 3des. See the OpenSSL documentation for more info. The key‐
2587 size is 128 bits (except for aes256). Here is one way to make a
2588 keyfile with that many bits:
2589 dd if=/dev/random of=./my.key bs=16 count=1
2591 you will need to securely share this key with the other side of
2593 the VNC connection (See SSVNC for examples).
2594 Example: -enc blowfish:./my.key Example: -enc blow‐
2596 fish:pw=swordfish
2597 By default 16 bytes of random salt followed by 16 bytes of ran‐
2599 dom initialization vector are sent at the very beginning of the
2600 stream. The other side must read these and initialize their
2601 cipher with them. These values make the session key unique
2602 (without them the security is minimal). Similarly, the other
2603 side must send us its random salt and IV with those same
2604 lengths.
2605 The salt and key data are combined to create a session key using
2607 an md5 hash as described in EVP_BytesToKey(3).
2608 The exact call is: EVP_BytesToKey(Cipher, EVP_md5(), salt, key‐
2610 data, len, 1, keystr, NULL); where salt is the random data as
2611 described above, and keydata is the shared secret key data.
2612 keystr is the resulting session key. The cipher is then seeded
2613 with keystr and uses the random initialization vector as its
2614 first block.
2615 To modify the amount of random salt and initialization vector
2617 use cipher@n,m where n is the salt length and m the initializa‐
2618 tion vector length. E.g.
2619 -enc aes-cfb@8,16:./my.key
2621 It is not a good idea to set either one to zero, although you
2623 may be forced to if the other side of the tunnel is not under
2624 your control.
2625 To skip the salt and EVP_BytesToKey MD5 entirely (no hashing is
2627 done: the keydata is directly inserted into the cipher) specify
2628 "-1" for the salt, e.g.
2629 -enc blowfish@-1,16:./my.key
2631 The message digest can also be changed to something besides the
2633 default MD5. Use cipher@md+n,m where "md" can be one of sha,
2634 sha1, md5, or ripe. For example:
2635 -enc arc4@sha+8,16:./my.key
2637 The SSVNC vnc viewer project supplies a symmetric encryption
2639 tool named "ultravnc_dsm_helper" that can be used on the viewer
2640 side. For example:
2641 ssvncviewer exec='ultravnc_dsm_helper arc4 my.key 0 h:p'
2643 (or replace 'ssvncviewer' with 'ssvnc -viewer') where h:p is the
2645 hostname and port of the x11vnc server. ultravnc_dsm_helper may
2646 also be used standalone to provide a symmetric encryption tunnel
2647 for any viewer or server (VNC or otherwise.) The cipher (1st
2648 arg) is basically the same syntax as we use above.
2649 Also see the 'Non-Ultra DSM' SSVNC option for the ´UltraVNC DSM
2651 Encryption Plugin' advanced option.
2652 For both ways of using the viewer, you can specify the salt,ivec
2654 sizes (in GUI or, e.g. arc4@8,16).
2655 -https [port]
2657 Use a special, separate HTTPS port (-ssl and -stunnel modes
2659 only) for HTTPS Java viewer applet downloading. I.e. not 5900
2660 and not 5800 (the defaults.)
2661 BACKGROUND: In -ssl mode, it turns out you can use the single
2663 VNC port (e.g. 5900) for both VNC and HTTPS connections. (HTTPS
2664 is used to retrieve a SSL-aware VncViewer.jar applet that is
2665 provided with x11vnc). Since both use SSL the implementation
2666 was extended to detect if HTTP traffic (i.e. GET) is taking
2667 place and handle it accordingly. The URL would be, e.g.:
2668 https://mymachine.org:5900/
2670 This is convenient for firewalls, etc, because only one port
2672 needs to be allowed in. However, this heuristic adds a few sec‐
2673 onds delay to each connection and can be unreliable (especially
2674 if the user takes much time to ponder the Certificate dialogs in
2675 his browser, Java VM, or VNC Viewer applet. That's right 3 sep‐
2676 arate "Are you sure you want to connect?" dialogs!)
2677 END OF BACKGROUND.
2679 USAGE: So use the -https option to provide a separate, more
2681 reliable HTTPS port that x11vnc will listen on. If [port] is
2682 not provided (or is 0), one is autoselected. The URL to use is
2683 printed out at startup.
2684 The SSL Java applet directory is specified via the -httpdir
2686 option. If not supplied, -https will try to guess the directory
2687 as though the -http option was supplied.
2688 -httpsredir [port]
2690 In -ssl mode with the Java applet retrieved via HTTPS, when the
2692 HTML file containing applet parameters ('index.vnc' or
2693 'proxy.vnc') is sent do NOT set the applet PORT parameter to the
2694 actual VNC port but set it to "port" instead. If "port" is not
2695 supplied, then the port number is guessed from the Host: HTTP
2696 header.
2697 This is useful when an incoming TCP connection redirection is
2699 performed by a router/gateway/firewall from one port to an
2700 internal machine where x11vnc is listening on a different port.
2701 The Java applet needs to connect to the firewall/router port,
2702 not the VNC port on the internal workstation. For example, one
2703 could redir from mygateway.com:443 to workstation:5900.
2704 This spares the user from having to type in https://mygate‐
2706 way.com/?PORT=443 into their web browser. Note that port 443 is
2707 the default https port; other ports must be explicitly indi‐
2708 cated, for example: https://mygateway.com:8000/?PORT=8000. To
2709 avoid having to include the PORT= in the browser URL, simply
2710 supply "-httpsredir" to x11vnc.
2711 This option does not work in -stunnel mode.
2713 More tricks: set the env var X11VNC_EXTRA_HTTPS_PARAMS to be
2715 extra URL parameters to use. This way you do not need to spec‐
2716 ify extra PARAMS in the index.vnc file. E.g. x11vnc -env
2717 X11VNC_EXTRA_HTTPS_PARAMS='?GET=1' ...
2718 If you do not want to expose the non-SSL HTTP port to the net‐
2720 work (i.e. you just want the single VNC/HTTPS port, e.g. 5900,
2721 open for connections) then specify the option -env
2722 X11VNC_HTTP_LISTEN_LOCALHOST=1 This way the connection to the
2723 LibVNCServer httpd server will only be available on localhost
2724 (note that in -ssl mode, HTTPS requests are redirected from SSL
2725 to the non-SSL LibVNCServer HTTP server.)
2726 -http_oneport
2728 For UN-encrypted connections mode (i.e. no -ssl, -stunnel, or
2730 -enc options), allow the Java VNC Viewer applet to be downloaded
2731 thru the VNC port via HTTP.
2732 That is to say, you can use a single port for Java applet viewer
2734 connections by using a URL in your web browser like this, for
2735 example:
2736 http://hostname:5900
2738 The regular, two-port mode, URL http://hostname:5800 will con‐
2740 tinue to work as well.
2741 As mentioned above, this mode will NOT work with the -ssl,
2743 -stunnel, or -enc encryption options. Note that is it equiva‐
2744 lent to '-enc none' (i.e. it uses the same detection mechanism
2745 as for HTTPS, but with no encryption.)
2746 HTTPS single-port is on by default in -ssl encrypted mode (and
2748 -enc too), so you only need -http_oneport when doing non-SSL
2749 encrypted connections.
2750 This mode could also be useful for SSH tunnels since it means
2752 only one port needs to be redirected.
2753 The -httpsredir option may also be useful for this mode when
2755 using an SSH tunnel as well as for router port redirections.
2756 Note that the -env X11VNC_HTTP_LISTEN_LOCALHOST=1 option
2758 described above under -httpsredir applies for the LibVNCServer
2759 httpd server in all cases (ssl or not.)
2760 -ssh user@host:disp
2762 Create a remote listening port on machine "host" via a SSH tun‐
2764 nel using the -R rport:localhost:lport method. lport will be the
2765 local x11vnc listening port, so a connection to rport
2766 (5900+disp) on "host" will reach x11vnc. E.g. fred@snoopy.com:0
2767 This could be useful if a firewall/router prevents incoming con‐
2769 nections to the x11vnc machine, but the ssh machine "host" can
2770 be reached by the VNC viewer. "user@" is not needed unless the
2771 remote unix username differs from the current one.
2772 By default the remote sshd is usually configured to listen only
2774 on localhost for rport, so the viewer may need to ssh -L redir
2775 to "host" as well (See SSVNC to automate this). The sshd set‐
2776 ting GatewayPorts enables listening on all interfaces for rport;
2777 viewers can reach it more easily.
2778 "disp" is the VNC display for the remote SSH side, e.g. 0 corre‐
2780 sponds to port 5900, etc. If disp is greater than 200 the value
2781 is used as the port. Use a negative value to force a low port,
2782 e.g. host:-80 will use port 80.
2783 If ssh-agent is not active, then the ssh password needs to be
2785 entered in the terminal where x11vnc is running.
2786 By default the remote ssh will issue a 'sleep 300' to wait for
2788 the incoming connection for 5 mins. To modify this use
2789 user@host:disp+secs.
2790 If the remote SSH server is on a non-standard port (i.e. not 22)
2792 use user@host:port:disp+secs.
2793 Note that the ssh process MAY NOT be killed when x11vnc exits.
2795 It tries by looking at ps(1) output.
2796 -users list
2798 If x11vnc is started as root (say from inetd(8) or from display
2800 managers xdm(1) , gdm(1) , etc), then as soon as possible after
2801 connections to the X display are established try to switch to
2802 one of the users in the comma separated list. If x11vnc is not
2803 running as root this option is ignored.
2804 Why use this option? In general it is not needed since x11vnc
2806 is already connected to the X display and can perform its pri‐
2807 mary functions. The option was added to make some of the
2808 *external* utility commands x11vnc occasionally runs work prop‐
2809 erly. In particular under GNOME and KDE to implement the
2810 "-solid color" feature external commands (gconftool-2 and dcop)
2811 unfortunately must be run as the user owning the desktop ses‐
2812 sion. Since this option switches userid it also affects the
2813 userid used to run the processes for the -accept and -gone
2814 options. It also affects the ability to read files for options
2815 such as -connect, -allow, and -remap and also the ultra and
2816 tight filetransfer feature if enabled. Note that the -connect
2817 file is also sometimes written to.
2818 So be careful with this option since in some situations its use
2820 can decrease security.
2821 In general the switch to a user will only take place if the dis‐
2823 play can still be successfully opened as that user (this is pri‐
2824 marily to try to guess the actual owner of the session). Exam‐
2825 ple: "-users fred,wilma,betty". Note that a malicious local
2826 user "barney" by quickly using "xhost +" when logging in may
2827 possibly get the x11vnc process to switch to user "fred". What
2828 happens next?
2829 Under display managers it may be a long time before the switch
2831 succeeds (i.e. a user logs in). To instead make it switch imme‐
2832 diately regardless if the display can be reopened prefix the
2833 username with the "+" character. E.g. "-users +bob" or "-users
2834 +nobody".
2835 The latter (i.e. switching immediately to user "nobody") is the
2837 only obvious use of the -users option that increases security.
2838 Use the following notation to associate a group with a user:
2840 user1.group1,user2.group2,... Note that initgroups(2) will
2841 still be called first to try to switch to ALL of a user's groups
2842 (primary and additional groups). Only if that fails or it is
2843 not available then the single group specified as above (or the
2844 user's primary group if not specified) is switched to with set‐
2845 gid(2). Use -env X11VNC_SINGLE_GROUP=1 to prevent trying init‐
2846 groups(2) and only switch to the single group. This sort of
2847 setting is only really needed to make the ultra or tight file‐
2848 transfer permissions work properly. This format applies to any
2849 comma separated list of users, even the special "=" modes
2850 described below.
2851 In -unixpw mode, if "-users unixpw=" is supplied then after a
2853 user authenticates himself via the -unixpw mechanism, x11vnc
2854 will try to switch to that user as though "-users +username" had
2855 been supplied. If you want to limit which users this will be
2856 done for, provide them as a comma separated list after "unixpw="
2857 Groups can also be specified as described above.
2858 Similarly, in -ssl mode, if "-users sslpeer=" is supplied then
2860 after an SSL client authenticates with his cert (the -sslverify
2861 option is required for this) x11vnc will extract a UNIX username
2862 from the "emailAddress" field (username@hostname.com) of the
2863 "Subject" of the x509 SSL cert and then try to switch to that
2864 user as though "-users +username" had been supplied. If you
2865 want to limit which users this will be done for, provide them as
2866 a comma separated list after "sslpeer=". Set the env. var
2867 X11VNC_SSLPEER_CN to use the Common Name (normally a hostname)
2868 instead of the Email field.
2869 NOTE: for sslpeer= mode the x11vnc administrator must take care
2871 that any client certs he adds to -sslverify have the intended
2872 UNIX username in the "emailAddress" field of the cert. Other‐
2873 wise a user may be able to log in as another. This command can
2874 be of use in checking: "openssl x509 -text -in file.crt", see
2875 the "Subject:" line. Also, along with the normal RFB_* env.
2876 vars. (see -accept) passed to external cmd= commands,
2877 RFB_SSL_CLIENT_CERT will be set to the client's x509 certificate
2878 string.
2879 The sslpeer= mode can aid finding X sessions via the FINDDISPLAY
2881 and FINDCREATEDISPLAY mechanisms.
2882 To immediately switch to a user *before* connections to the X
2884 display are made or any files opened use the "=" character:
2885 "-users =bob". That user needs to be able to open the X display
2886 and any files of course.
2887 The special user "guess=" means to examine the utmpx database
2889 (see who(1) ) looking for a user attached to the display number
2890 (from DISPLAY or -display option) and try him/her. To limit the
2891 list of guesses, use: "-users guess=bob,betty".
2892 Even more sinister is the special user "lurk=" that means to try
2894 to guess the DISPLAY from the utmpx login database as well. So
2895 it "lurks" waiting for anyone to log into an X session and then
2896 connects to it. Specify a list of users after the = to limit
2897 which users will be tried. To enable a different searching
2898 mode, if the first user in the list is something like ":0" or
2899 ":0-2" that indicates a range of DISPLAY numbers that will be
2900 tried (regardless of whether they are in the utmpx database) for
2901 all users that are logged in. Also see the "-display WAIT:..."
2902 functionality. Examples: "-users lurk=" and also "-users
2903 lurk=:0-1,bob,mary"
2904 Be especially careful using the "guess=" and "lurk=" modes.
2906 They are not recommended for use on machines with untrustworthy
2907 local users.
2908 -noshm
2910 Do not use the MIT-SHM extension for the polling. Remote dis‐
2912 plays can be polled this way: be careful this can use large
2913 amounts of network bandwidth. This is also of use if the local
2914 machine has a limited number of shm segments and -onetile is not
2915 sufficient.
2916 -flipbyteorder
2918 Sometimes needed if remotely polled host has different endian‐
2920 ness. Ignored unless -noshm is set.
2921 -onetile
2923 Do not use the new copy_tiles() framebuffer mechanism, just use
2925 1 shm tile for polling. Limits shm segments used to 3.
2926 To disable any automatic shm reduction set the env. var.
2928 X11VNC_NO_LIMIT_SHM.
2929 -solid [color]
2931 To improve performance, when VNC clients are connected try to
2933 change the desktop background to a solid color. The [color] is
2934 optional: the default color is "cyan4". For a different one
2935 specify the X color (rgb.txt name, e.g. "darkblue" or numerical
2936 "#RRGGBB").
2937 Currently this option only works on GNOME, KDE, CDE, XFCE, and
2939 classic X (i.e. with the background image on the root window).
2940 The "gconftool-2", "dcop" and "xfconf-query" external commands
2941 are run for GNOME, KDE, and XFCE respectively. This also works
2942 on native MacOSX. (There is no color selection for MacOSX or
2943 XFCE.) Other desktops won't work, (send us the corresponding
2944 commands if you find them). If x11vnc is running as root (
2945 inetd(8) or gdm(1) ), the -users option may be needed for GNOME,
2946 KDE, XFCE. If x11vnc guesses your desktop incorrectly, you can
2947 force it by prefixing color with "gnome:", "kde:", "cde:",
2948 "xfce:", or "root:".
2949 Update: -solid no longer works on KDE4.
2951 This mode works in a limited way on the Mac OS X Console with
2953 one color ('kelp') using the screensaver writing to the back‐
2954 ground. Look in "~/Library/Screen Savers" for VncSolidColor.png
2955 to change the color.
2956 -blackout string
2958 Black out rectangles on the screen. string is a comma separated
2960 list of WxH+X+Y type geometries for each rectangle. If one of
2961 the items on the list is the string "noptr" the mouse pointer
2962 will not be allowed to go into a blacked out region.
2963 -xinerama, -noxinerama
2965 If your screen is composed of multiple monitors glued together
2967 via XINERAMA, and that screen is not a rectangle this option
2968 will try to guess the areas to black out (if your system has
2969 libXinerama). default: -xinerama
2970 In general, we have noticed on XINERAMA displays you may need to
2972 use the "-xwarppointer" option if the mouse pointer misbehaves
2973 and it is enabled by default. Use "-noxwarppointer" if you do
2974 not want this.
2975 -xtrap
2977 Use the DEC-XTRAP extension for keystroke and mouse input inser‐
2979 tion. For use on legacy systems, e.g. X11R5, running an incom‐
2980 plete or missing XTEST extension. By default DEC-XTRAP will be
2981 used if XTEST server grab control is missing, use -xtrap to do
2982 the keystroke and mouse insertion via DEC-XTRAP as well.
2983 -xrandr [mode]
2985 If the display supports the XRANDR (X Resize, Rotate and Reflec‐
2987 tion) extension, and you expect XRANDR events to occur to the
2988 display while x11vnc is running, this options indicates x11vnc
2989 should try to respond to them (as opposed to simply crashing by
2990 assuming the old screen size). See the xrandr(1) manpage and
2991 run ´xrandr -q' for more info. [mode] is optional and described
2992 below.
2993 Since watching for XRANDR events and trapping errors increases
2995 polling overhead, only use this option if XRANDR changes are
2996 expected. For example on a rotatable screen PDA or laptop, or
2997 using a XRANDR-aware Desktop where you resize often. It is best
2998 to be viewing with a vncviewer that supports the NewFBSize
2999 encoding, since it knows how to react to screen size changes.
3000 Otherwise, LibVNCServer tries to do so something reasonable for
3001 viewers that cannot do this (portions of the screen may be
3002 clipped, unused, etc).
3003 Note: the default now is to check for XRANDR events, but do not
3005 trap every X call that may fail due to resize. If a resize
3006 event is received, the full -xrandr mode is enabled. To disable
3007 even checking for events supply: -noxrandr.
3008 "mode" defaults to "resize", which means create a new, resized,
3010 framebuffer and hope all viewers can cope with the change.
3011 "newfbsize" means first disconnect all viewers that do not sup‐
3012 port the NewFBSize VNC encoding, and then resize the frame‐
3013 buffer. "exit" means disconnect all viewer clients, and then
3014 terminate x11vnc.
3015 -rotate string
3017 Rotate and/or flip the framebuffer view exported by VNC. This
3019 transformation is independent of XRANDR and is done in software
3020 in main memory and so may be slower. This mode could be useful
3021 on a handheld with portrait or landscape modes that do not cor‐
3022 respond to the scanline order of the actual framebuffer. string
3023 can be:
3024 x flip along x-axis y flip along y-axis xy flip
3026 along x- and y-axes +90 rotate 90 degrees clockwise -90
3027 rotate 90 degrees counter-clockwise +90x rotate 90 degrees
3028 CW, then flip along x +90y rotate 90 degrees CW, then flip
3029 along y
3030 these give all possible rotations and reflections.
3032 Aliases: same as xy: yx, +180, -180, 180 same as -90: +270, 270
3034 same as +90: 90, (ditto for 90x, 90y)
3035 Like -scale, this transformation is applied at the very end of
3037 any chain of framebuffer transformations and so any options with
3038 geometries, e.g. -blackout, -clip, etc. are relative to the
3039 original X (or -rawfb) framebuffer, not the final one sent to
3040 VNC viewers.
3041 If you do not want the cursor shape to be rotated prefix string
3043 with "nc:", e.g. "nc:+90", "nc:xy", etc.
3044 -padgeom WxH
3046 Whenever a new vncviewer connects, the framebuffer is replaced
3048 with a fake, solid black one of geometry WxH. Shortly after‐
3049 wards the framebuffer is replaced with the real one. This is
3050 intended for use with vncviewers that do not support NewFBSize
3051 and one wants to make sure the initial viewer geometry will be
3052 big enough to handle all subsequent resizes (e.g. under -xrandr,
3053 -remote id:windowid, rescaling, etc.)
3054 In -unixpw mode this sets the size of the login screen. Use
3056 "once:WxH" it ignore padgeom after the login screen is set up.
3057 -o logfile
3059 Write stderr messages to file logfile instead of to the termi‐
3061 nal. Same as "-logfile file". To append to the file use "-oa
3062 file" or "-logappend file". If logfile contains the string
3063 "%VNCDISPLAY" it is expanded to the vnc display (the name may
3064 need to be guessed at.) "%HOME" works too.
3065 -flag file
3067 Write the "PORT=NNNN" (e.g. PORT=5900) string to file in addi‐
3069 tion to stdout. This option could be useful by wrapper script
3070 to detect when x11vnc is ready.
3071 -rmflag file
3073 Remove file at exit to signal when x11vnc is done. The file is
3075 created at startup if it does not already exist or if file is
3076 prefixed with "create:". If the file is created, the x11vnc PID
3077 is placed in the file. Otherwise the files contents is not
3078 changed. Use prefix "nocreate:" to prevent creation.
3079 -rc filename
3081 Use filename instead of $HOME/.x11vncrc for rc file.
3083 -norc
3085 Do not process any .x11vncrc file for options.
3087 -env VAR=VALUE
3089 Set the environment variable 'VAR' to value 'VALUE' at x11vnc
3091 startup. This is a convenience utility to avoid shell script
3092 wrappers, etc. to set the env. var. You may specify as many of
3093 these as needed on the command line.
3094 -prog /path/to/x11vnc
3096 Set the full path to the x11vnc program for cases when it cannot
3098 be determined from argv[0] (e.g. tcpd/inetd)
3099 -h, -help
3101 Print this help text. -?, -opts Only list the
3103 x11vnc options.
3104 -V, -version
3106 Print program version and last modification date.
3108 -license
3110 Print out license information. Same as -copying and -warranty.
3112 -dbg
3114 Instead of exiting after cleaning up, run a simple "debug crash
3116 shell" when fatal errors are trapped.
3117 -q, -quiet
3119 Be quiet by printing less informational output to stderr. (use
3121 -noquiet to undo an earlier -quiet.)
3122 The -quiet option does not eliminate all informational output,
3124 it only reduces it. It is ignored in most auxiliary usage
3125 modes, e.g. -storepasswd. To eliminate all output use:
3126 2>/dev/null 1>&2, etc.
3127 -v, -verbose
3129 Print out more information to stderr.
3131 -bg
3133 Go into the background after screen setup. Messages to stderr
3135 are lost unless -o logfile is used. Something like this could
3136 be useful in a script:
3137 port=`ssh -t $host "x11vnc -display :0 -bg" | grep PORT`
3139 port=`echo "$port" | sed -e 's/PORT=//'`
3141 port=`expr $port - 5900`
3143 vncviewer $host:$port
3145 -modtweak, -nomodtweak
3147 Option -modtweak automatically tries to adjust the AltGr and
3149 Shift modifiers for differing language keyboards between client
3150 and host. Otherwise, only a single key press/release of a Key‐
3151 code is simulated (i.e. ignoring the state of the modifiers:
3152 this usually works for identical keyboards). Also useful in
3153 resolving cases where a Keysym is bound to multiple keys (e.g.
3154 "<" + ">" and "," + "<" keys). Default: -modtweak
3155 If you are having trouble with with keys and -xkb or -noxkb, and
3157 similar things don't help, try -nomodtweak.
3158 On some HP-UX systems it is been noted that they have an odd
3160 keymapping where a single keycode will have a keysym, e.g. "#",
3161 up to three times. You can check via "xmodmap -pk" or the -dk
3162 option. The failure is when you try to type "#" it yields "3".
3163 If you see this problem try setting the environment variable
3164 MODTWEAK_LOWEST=1 to see if it helps.
3165 -xkb, -noxkb
3167 When in modtweak mode, use the XKEYBOARD extension (if the X
3169 display supports it) to do the modifier tweaking. This is pow‐
3170 erful and should be tried if there are still keymapping problems
3171 when using -modtweak by itself. The default is to check whether
3172 some common keysyms, e.g. !, @, [, are only accessible via -xkb
3173 mode and if so then automatically enable the mode. To disable
3174 this automatic detection use -noxkb.
3175 When -xkb mode is active you can set these env. vars. They
3177 apply only when there is ambiguity as to which key to choose
3178 (i.e the mapping is not one-to-one). NOKEYHINTS=1: for up ascii
3179 keystrokes do not use score hints saved when the key was pressed
3180 down. NOANYDOWN=1: for up keystrokes do not resort to searching
3181 through keys that are currently pressed down. KEYSDOWN=N:
3182 remember the last N keys press down for tie-breaking when an up
3183 keystroke comes in.
3184 -capslock
3186 When in -modtweak (the default) or -xkb mode, if a keysym in the
3188 range A-Z comes in check the X server to see if the Caps_Lock is
3189 set. If it is do not artificially press Shift to generate the
3190 keysym. This will enable the CapsLock key to behave correctly
3191 in some circumstances: namely *both* the VNC viewer machine and
3192 the x11vnc X server are in the CapsLock on state. If one side
3193 has CapsLock on and the other off and the keyboard is not behav‐
3194 ing as you think it should you should correct the CapsLock
3195 states (hint: pressing CapsLock inside and outside of the viewer
3196 can help toggle them both to the correct state). However, for
3197 best results do not use this option, but rather *only* enable
3198 CapsLock on the VNC viewer side (i.e. by pressing CapsLock out‐
3199 side of the viewer window, also -skip_lockkeys below). Also try
3200 -nomodtweak for a possible workaround.
3201 -skip_lockkeys, -noskip_lockkeys
3203 Have x11vnc ignore all Caps_Lock, Shift_Lock, Num_Lock,
3205 Scroll_Lock keysyms received from viewers. The idea is you
3206 press Caps_Lock on the VNC Viewer side but that does not change
3207 the lock state in the x11vnc-side X server. Nevertheless your
3208 capitalized letters come in over the wire and are applied cor‐
3209 rectly to the x11vnc-side X server. Note this mode probably
3210 won't do what you want in -nomodtweak mode. Also, a kludge for
3211 KP_n digits is always done in this mode: they are mapped to reg‐
3212 ular digit keysyms. See also -capslock above. The default is
3213 -noskip_lockkeys.
3214 -skip_keycodes string
3216 Ignore the comma separated list of decimal keycodes. Perhaps
3218 these are keycodes not on your keyboard but your X server thinks
3219 exist. Currently only applies to -xkb mode. Use this option to
3220 help x11vnc in the reverse problem it tries to solve: Keysym ->
3221 Keycode(s) when ambiguities exist (more than one Keycode per
3222 Keysym). Run 'xmodmap -pk' to see your keymapping. Example:
3223 "-skip_keycodes 94,114"
3224 -sloppy_keys
3226 Experimental option that tries to correct some "sloppy" key
3228 behavior. E.g. if at the viewer you press Shift+Key but then
3229 release the Shift before Key that could give rise to extra
3230 unwanted characters (usually only between keyboards of different
3231 languages). Only use this option if you observe problems with
3232 some keystrokes.
3233 -skip_dups, -noskip_dups
3235 Some VNC viewers send impossible repeated key events, e.g. key-
3237 down, key-down, key-up, key-up all for the same key, or 20 downs
3238 in a row for the same modifier key! Setting -skip_dups means to
3239 skip these duplicates and just process the first event. Note:
3240 some VNC viewers assume they can send down's without the corre‐
3241 sponding up's and so you should not set this option for these
3242 viewers (symptom: some keys do not autorepeat) Default:
3243 -noskip_dups
3244 -add_keysyms, -noadd_keysyms
3246 If a Keysym is received from a VNC viewer and that Keysym does
3248 not exist in the X server, then add the Keysym to the X server's
3249 keyboard mapping on an unused key. Added Keysyms will be
3250 removed periodically and also when x11vnc exits. Default:
3251 -add_keysyms
3252 -clear_mods
3254 At startup and exit clear the modifier keys by sending KeyRe‐
3256 lease for each one. The Lock modifiers are skipped. Used to
3257 clear the state if the display was accidentally left with any
3258 pressed down.
3259 -clear_keys
3261 As -clear_mods, except try to release ANY pressed key. Note
3263 that this option and -clear_mods can interfere with a person
3264 typing at the physical keyboard.
3265 -clear_all
3267 As -clear_keys, except try to release any CapsLock, NumLock,
3269 etc. locks as well.
3270 -remap string
3272 Read Keysym remappings from file named string. Format is one
3274 pair of Keysyms per line (can be name or hex value) separated by
3275 a space. If no file named string exists, it is instead inter‐
3276 preted as this form: key1-key2,key3-key4,... See
3277 <X11/keysymdef.h> header file for a list of Keysym names, or use
3278 xev(1).
3279 To map a key to a button click, use the fake Keysyms "Button1",
3281 ..., etc. E.g: "-remap Super_R-Button2" (useful for pasting on a
3282 laptop)
3283 I use these if the machine I am viewing from does not have a
3285 scrollwheel or I don't like using the one it has:
3286 -remap Super_R-Button4,Menu-Button5 -remap KP_Add-But‐
3288 ton4,KP_Enter-Button5
3289 the former would be used on a PC, the latter on a MacBook. This
3291 way those little used keys can be used to generate bigger hops
3292 than the Up and Down arrows provide. One can scroll through
3293 text or web pages more quickly this way (especially if x11vnc
3294 scroll detection is active.)
3295 Use Button44, Button12, etc. for multiple clicks.
3297 To disable a keysym (i.e. make it so it will not be injected),
3299 remap it to "NoSymbol" or "None".
3300 Dead keys: "dead" (or silent, mute) keys are keys that do not
3302 produce a character but must be followed by a 2nd keystroke.
3303 This is often used for accenting characters, e.g. to put "`" on
3304 top of "a" by pressing the dead key and then "a". Note that
3305 this interpretation is not part of core X11, it is up to the
3306 toolkit or application to decide how to react to the sequence.
3307 The X11 names for these keysyms are "dead_grave", "dead_acute",
3308 etc. However some VNC viewers send the keysyms "grave", "acute"
3309 instead thereby disabling the accenting. To work around this
3310 -remap can be used. For example "-remap grave-dead_grave,acute-
3311 dead_acute"
3312 As a convenience, "-remap DEAD" applies these remaps:
3314 g grave-dead_grave
3316 a acute-dead_acute
3317 c asciicircum-dead_circumflex
3318 t asciitilde-dead_tilde
3319 m macron-dead_macron
3320 b breve-dead_breve
3321 D abovedot-dead_abovedot
3322 d diaeresis-dead_diaeresis
3323 o degree-dead_abovering
3324 A doubleacute-dead_doubleacute
3325 r caron-dead_caron
3326 e cedilla-dead_cedilla
3327 If you just want a subset use the first letter label, e.g.
3329 "-remap DEAD=ga" to get the first two. Additional remaps may
3330 also be supplied via commas, e.g. "-remap DEAD=ga,Super_R-But‐
3331 ton2". Finally, "DEAD=missing" means to apply all of the above
3332 as long as the left hand member is not already in the X11
3333 keymap.
3334 -norepeat, -repeat
3336 Option -norepeat disables X server key auto repeat when VNC
3338 clients are connected and VNC keyboard input is not idle for
3339 more than 5 minutes. This works around a repeating keystrokes
3340 bug (triggered by long processing delays between key down and
3341 key up client events: either from large screen changes or high
3342 latency). Default: -norepeat
3343 You can set the env. var. X11VNC_IDLE_TIMEOUT to the number of
3345 idle seconds you want (5min = 300secs).
3346 Note: your VNC viewer side will likely do autorepeating, so this
3348 is no loss unless someone is simultaneously at the real X dis‐
3349 play.
3350 Use "-norepeat N" to set how many times norepeat will be reset
3352 if something else (e.g. X session manager) undoes it. The
3353 default is 2. Use a negative value for unlimited resets.
3354 -nofb
3356 Ignore video framebuffer: only process keyboard and pointer.
3358 Intended for use with Win2VNC and x2vnc dual-monitor setups.
3359 -nobell
3361 Do not watch for XBell events. (no beeps will be heard) Note:
3363 XBell monitoring requires the XKEYBOARD extension.
3364 -nosel
3366 Do not manage exchange of X selection/cutbuffer between VNC
3368 viewers and the X server at all.
3369 -noprimary
3371 Do not poll the PRIMARY selection for changes to send back to
3373 clients. (PRIMARY is still set on received changes, however).
3374 -nosetprimary
3376 Do not set the PRIMARY selection for changes received from VNC
3378 clients.
3379 -noclipboard
3381 Do not poll the CLIPBOARD selection for changes to send back to
3383 clients. (CLIPBOARD is still set on received changes, however).
3384 -nosetclipboard
3386 Do not set the CLIPBOARD selection for changes received from VNC
3388 clients.
3389 -seldir string
3391 If direction string is "send", only send the selection to view‐
3393 ers, and if it is "recv" only receive it from viewers. To work
3394 around apps setting the selection too frequently and messing up
3395 the other end. You can actually supply a comma separated list
3396 of directions, including "debug" to turn on debugging output.
3397 -cursor [mode], -nocursor
3399 Sets how the pointer cursor shape (little icon at the mouse
3401 pointer) should be handled. The "mode" string is optional and
3402 is described below. The default is to show some sort of cursor
3403 shape(s). How this is done depends on the VNC viewer and the X
3404 server. Use -nocursor to disable cursor shapes completely.
3405 Some VNC viewers support the TightVNC CursorPosUpdates and Cur‐
3407 sorShapeUpdates extensions (cuts down on network traffic by not
3408 having to send the cursor image every time the pointer is
3409 moved), in which case these extensions are used (see -nocursor‐
3410 shape and -nocursorpos below to disable). For other viewers the
3411 cursor shape is written directly to the framebuffer every time
3412 the pointer is moved or changed and gets sent along with the
3413 other framebuffer updates. In this case, there will be some lag
3414 between the vnc viewer pointer and the remote cursor position.
3415 If the X display supports retrieving the cursor shape informa‐
3417 tion from the X server, then the default is to use that mode.
3418 On Solaris this can be done with the SUN_OVL extension using
3419 -overlay (see also the -overlay_nocursor option). A similar
3420 overlay scheme is used on IRIX. Xorg (e.g. Linux) and recent
3421 Solaris Xsun servers support the XFIXES extension to retrieve
3422 the exact cursor shape from the X server. If XFIXES is present
3423 it is preferred over Overlay and is used by default (see -nox‐
3424 fixes below). This can be disabled with -nocursor, and also
3425 some values of the "mode" option below.
3426 Note that under XFIXES cursors with transparency (alpha channel)
3428 will usually not be exactly represented and one may find Overlay
3429 preferable. See also the -alphacut and -alphafrac options below
3430 as fudge factors to try to improve the situation for cursors
3431 with transparency for a given theme.
3432 The "mode" string can be used to fine-tune the displaying of
3434 cursor shapes. It can be used the following ways:
3435 "-cursor arrow" - just show the standard arrow nothing more or
3437 nothing less.
3438 "-cursor none" - same as "-nocursor"
3440 "-cursor X" - when the cursor appears to be on the root window,
3442 draw the familiar X shape. Some desktops such as GNOME cover up
3443 the root window completely, and so this will not work, try "X1",
3444 etc, to try to shift the tree depth. On high latency links or
3445 slow machines there will be a time lag between expected and the
3446 actual cursor shape.
3447 "-cursor some" - like "X" but use additional heuristics to try
3449 to guess if the window should have a windowmanager-like resizer
3450 cursor or a text input I-beam cursor. This is a complete hack,
3451 but may be useful in some situations because it provides a lit‐
3452 tle more feedback about the cursor shape.
3453 "-cursor most" - try to show as many cursors as possible. Often
3455 this will only be the same as "some" unless the display has
3456 overlay visuals or XFIXES extensions available. On Solaris and
3457 IRIX if XFIXES is not available, -overlay mode will be
3458 attempted.
3459 -cursor_drag
3461 Show cursor shape changes even when the mouse is being dragged
3463 with a mouse button down. This is useful if you want to be able
3464 to see Drag-and-Drop cursor icons, etc.
3465 -arrow n
3467 Choose an alternate "arrow" cursor from a set of some common
3469 ones. n can be 1 to 6. Default is: 1 Ignored when in XFIXES
3470 cursor-grabbing mode.
3471 -noxfixes
3473 Do not use the XFIXES extension to draw the exact cursor shape
3475 even if it is available.
3476 Note: To work around a crash in Xorg 1.5 and later some people
3478 needed to use -noxfixes. The Xorg crash occurred right after a
3479 Display Manager (e.g. GDM) login. Starting with x11vnc 0.9.9 it
3480 tries to automatically avoid using XFIXES until it is sure a
3481 window manager is running. See the -reopen option for more info
3482 and how to use X11VNC_AVOID_WINDOWS=never to disable it.
3483 -alphacut n
3485 When using the XFIXES extension for the cursor shape, cursors
3487 with transparency will not usually be displayed exactly (but
3488 opaque ones will). This option sets n as a cutoff for cursors
3489 that have transparency ("alpha channel" with values ranging from
3490 0 to 255) Any cursor pixel with alpha value less than n becomes
3491 completely transparent. Otherwise the pixel is completely
3492 opaque. Default 240
3493 -alphafrac fraction
3495 With the threshold in -alphacut some cursors will become almost
3497 completely transparent because their alpha values are not high
3498 enough. For those cursors adjust the alpha threshold until
3499 fraction of the non-zero alpha channel pixels become opaque.
3500 Default 0.33
3501 -alpharemove
3503 By default, XFIXES cursors pixels with transparency have the
3505 alpha factor multiplied into the RGB color values (i.e. that
3506 corresponding to blending the cursor with a black background).
3507 Specify this option to remove the alpha factor. (useful for
3508 light colored semi-transparent cursors).
3509 -noalphablend
3511 In XFIXES mode do not send cursor alpha channel data to LibVNC‐
3513 Server. The default is to send it. The alphablend effect will
3514 only be visible in -nocursorshape mode or for clients with cur‐
3515 sorshapeupdates turned off. (However there is a hack for 32bpp
3516 with depth 24, it uses the extra 8 bits to store cursor trans‐
3517 parency for use with a hacked vncviewer that applies the trans‐
3518 parency locally. See the FAQ for more info).
3519 -nocursorshape
3521 Do not use the TightVNC CursorShapeUpdates extension even if
3523 clients support it. See -cursor above.
3524 -cursorpos, -nocursorpos
3526 Option -cursorpos enables sending the X cursor position back to
3528 all vnc clients that support the TightVNC CursorPosUpdates
3529 extension. Other clients will be able to see the pointer
3530 motions. Default: -cursorpos
3531 -xwarppointer, -noxwarppointer
3533 Move the pointer with XWarpPointer(3X) instead of the XTEST
3535 extension. Use this as a workaround if the pointer motion
3536 behaves incorrectly, e.g. on touchscreens or other non-standard
3537 setups.
3538 It is also sometimes needed on XINERAMA displays and is enabled
3540 by default if XINERAMA is found to be active. To prevent this,
3541 use -noxwarppointer.
3542 Also since 2009 there is an Xorg bug where the pointer cannot be
3544 moved properly on multiscreen displays. If x11vnc detects a
3545 multiscreen display it activates this option. To prevent this,
3546 use -noxwarppointer.
3547 -always_inject
3549 Even if there is no displacement (dx = dy = 0) for a VNC mouse
3551 event force the pointer to the indicated x,y position anyway.
3552 Recent (2009) gui toolkits (gnome) have problems with x11vnc's
3553 original mouse input injection method. So x11vnc's mouse input
3554 injection method has been modified. To regain the OLD behavior
3555 use this option: -always_inject. Then x11vnc will always force
3556 positioning the mouse to the x,y position even if that position
3557 has not changed since the previous VNC input event.
3558 The first place this problem was noticed was in gnome terminal:
3560 if you pressed and released mouse button 3, a menu was posted
3561 and then its first element 'New Terminal Window' was activated.
3562 This was because x11vnc injected the mouse position twice: once
3563 on ButtonPress and again on ButtonRelease. The toolkit inter‐
3564 preted the 2nd one as mouse motion even though the mouse hadn't
3565 moved. So now by default x11vnc tries to avoid injecting the
3566 2nd one.
3567 Note that with the new default x11vnc will be oblivious to
3569 applications moving the pointer (warping) or the user at the
3570 physical display moving it. So it might, e.g., inject ButtonRe‐
3571 lease at the wrong position. If this (or similar scenarios)
3572 causes problems in your environment, specify -always_inject for
3573 the old method.
3574 -buttonmap string
3576 String to remap mouse buttons. Format: IJK-LMN, this maps but‐
3578 tons I -> L, etc., e.g. -buttonmap 13-31
3579 Button presses can also be mapped to keystrokes: replace a but‐
3581 ton digit on the right of the dash with :<sym>: or
3582 :<sym1>+<sym2>: etc. for multiple keys. For example, if the
3583 viewing machine has a mouse-wheel (buttons 4 5) but the x11vnc
3584 side does not, these will do scrolls:
3585 -buttonmap 12345-123:Prior::Next:
3587 -buttonmap 12345-123:Up+Up+Up::Down+Down+Down:
3589 See <X11/keysymdef.h> header file for a list of Keysyms, or use
3591 the xev(1) program. Note: mapping of button clicks to Keysyms
3592 may not work if -modtweak or -xkb is needed for the Keysym.
3593 If you include a modifier like "Shift_L" the modifier's up/down
3595 state is toggled, e.g. to send "The" use :Shift_L+t+Shift_L+h+e:
3596 (the 1st one is shift down and the 2nd one is shift up). (note:
3597 the initial state of the modifier is ignored and not reset) To
3598 include button events use "Button1", ... etc.
3599 -buttonmap currently does not work on MacOSX console or in
3601 -rawfb mode.
3602 Workaround: use -buttonmap IJ...-LM...=n to limit the number of
3604 mouse buttons to n, e.g. 123-123=3. This will prevent x11vnc
3605 from crashing if the X server reports there are 5 buttons (4/5
3606 scroll wheel), but there are only really 3.
3607 -nodragging
3609 Do not update the display during mouse dragging events (mouse
3611 button held down). Greatly improves response on slow setups,
3612 but you lose all visual feedback for drags, text selection, and
3613 some menu traversals. It overrides any -pointer_mode setting.
3614 -ncache n
3616 Client-side caching scheme. Framebuffer memory n (an integer)
3618 times that of the full display is allocated below the actual
3619 framebuffer to cache screen contents for rapid retrieval. So a
3620 W x H frambuffer is expanded to a W x (n+1)*H one. Use 0 to
3621 disable.
3622 The n is actually optional, the default is 10.
3624 For this and the other -ncache* options below you can abbreviate
3626 "-ncache" with "-nc". Also, "-nonc" is the same as "-ncache 0"
3627 This is an experimental option, currently implemented in an awk‐
3629 ward way in that in the VNC Viewer you can see the pixel cache
3630 contents if you scroll down, etc. So you will have to set
3631 things up so you can't see that region. If this method is suc‐
3632 cessful, the changes required for clients to do this less awk‐
3633 wardly will be investigated.
3634 The SSVNC viewer does a good job at automatically hiding the
3636 pixel cache region. Or use SSVNC's -ycrop option to explicitly
3637 hide the region.
3638 Note that this mode consumes a huge amount of memory, both on
3640 the x11vnc server side and on the VNC Viewer side. If n=2 then
3641 the amount of RAM used is roughly tripled for both x11vnc and
3642 the VNC Viewer. As a rule of thumb, note that 1280x1024 at
3643 depth 24 is about 5MB of pixel data.
3644 For reasonable response when cycling through 4 to 6 large (e.g.
3646 web browser) windows a value n of 6 to 12 is recommended.
3647 (that's right: ~10X more memory...)
3648 Because of the way window backingstore and saveunders are imple‐
3650 mented, n must be even. It will be incremented by 1 if it is
3651 not.
3652 This mode also works for native MacOS X, but may not be as
3654 effective as the X version. This is due to a number of things,
3655 one is the drop-shadow compositing that leaves extra areas that
3656 need to be repaired (see -ncache_pad). Another is the window
3657 iconification animations need to be avoided (see -macicontime).
3658 It appears the that the 'Scale' animation mode gives better
3659 results than the 'Genie' one. Also, window event detection not
3660 as accurate as the X version.
3661 -ncache_cr
3663 In -ncache mode, try to do copyrect opaque window moves/drags
3665 instead of wireframes (this can induce painting errors). The
3666 wireframe will still be used when moving a window whose save-
3667 unders has not yet been set or has been invalidated.
3668 Some VNC Viewers provide better response than others with this
3670 option. On Unix, realvnc viewer gives smoother drags than
3671 tightvnc viewer. Response may also be choppy if the server side
3672 machine is too slow.
3673 Sometimes on very slow modem connections, this actually gives an
3675 improvement because no pixel data at all (not even the box ani‐
3676 mation) is sent during the drag.
3677 -ncache_no_moveraise
3679 In -ncache mode, do not assume that moving a window will cause
3681 the window manager to raise it to the top of the stack. The
3682 default is to assume it does, and so at the beginning of any
3683 wireframe, etc, window moves the window will be pushed to top in
3684 the VNC viewer.
3685 -ncache_no_dtchange
3687 In -ncache mode, do not try to guess when the desktop (viewport)
3689 changes to another one (i.e. another workarea). The default is
3690 to try to guess and when detected try to make the transistion
3691 more smoothly.
3692 -ncache_no_rootpixmap
3694 In -ncache mode, do not try to snapshot the desktop background
3696 to use in guessing or reconstructing window save-unders.
3697 -ncache_keep_anims
3699 In -ncache mode, do not try to disable window manager animations
3701 and other effects (that usually degrade ncache performance or
3702 cause painting errors). The default is to try to disable them
3703 on KDE (but not GNOME) when VNC clients are connected.
3704 For other window managers or desktops that provide animations,
3706 effects, compositing, translucency, etc. that interfere with the
3707 -ncache method you will have to disable them manually.
3708 -ncache_old_wm
3710 In -ncache mode, enable some heuristics for old style window
3712 managers such as fvwm and twm.
3713 -ncache_pad n
3715 In -ncache mode, pad each window with n pixels for the caching
3717 rectangles. This can be used to try to improve the situation
3718 with dropshadows or other compositing (e.g. MacOS X window man‐
3719 ager), although it could make things worse. The default is 0 on
3720 Unix and 24 on MacOS X.
3721 -debug_ncache
3723 Turn on debugging and profiling output under -ncache.
3725 -wireframe [str], -nowireframe
3727 Try to detect window moves or resizes when a mouse button is
3729 held down and show a wireframe instead of the full opaque win‐
3730 dow. This is based completely on heuristics and may not always
3731 work: it depends on your window manager and even how you move
3732 things around. See -pointer_mode below for discussion of the
3733 "bogging down" problem this tries to avoid. Default: -wireframe
3734 Shorter aliases: -wf [str] and -nowf
3736 The value "str" is optional and, of course, is packed with many
3738 tunable parameters for this scheme:
3739 Format: shade,linewidth,percent,T+B+L+R,mod,t1+t2+t3+t4 Default:
3741 0xff,2,0,32+8+8+8,all,0.15+0.30+5.0+0.125
3742 If you leave nothing between commas: ",," the default value is
3744 used. If you don't specify enough commas, the trailing parame‐
3745 ters are set to their defaults.
3746 "shade" indicate the "color" for the wireframe, usually a
3748 greyscale: 0-255, however for 16 and 32bpp you can specify an
3749 rgb.txt X color (e.g. "dodgerblue") or a value > 255 is treated
3750 as RGB (e.g. red is 0xff0000). "linewidth" sets the width of
3751 the wireframe in pixels. "percent" indicates to not apply the
3752 wireframe scheme to windows with area less than this percent of
3753 the full screen.
3754 "T+B+L+R" indicates four integers for how close in pixels the
3756 pointer has to be from the Top, Bottom, Left, or Right edges of
3757 the window to consider wireframing. This is a speedup to
3758 quickly exclude a window from being wireframed: set them all to
3759 zero to not try the speedup (scrolling and selecting text will
3760 likely be slower).
3761 "mod" specifies if a button down event in the interior of the
3763 window with a modifier key (Alt, Shift, etc.) down should indi‐
3764 cate a wireframe opportunity. It can be "0" or "none" to skip
3765 it, "1" or "all" to apply it to any modifier, or "Shift", "Alt",
3766 "Control", "Meta", "Super", or "Hyper" to only apply for that
3767 type of modifier key.
3768 "t1+t2+t3+t4" specify four floating point times in seconds: t1
3770 is how long to wait for the pointer to move, t2 is how long to
3771 wait for the window to start moving or being resized (for some
3772 window managers this can be rather long), t3 is how long to keep
3773 a wireframe moving before repainting the window. t4 is the mini‐
3774 mum time between sending wireframe "animations". If a slow link
3775 is detected, these values may be automatically changed to some‐
3776 thing better for a slow link.
3777 -nowireframelocal
3779 By default, mouse motion and button presses of a user sitting at
3781 the LOCAL display are monitored for wireframing opportunities
3782 (so that the changes will be sent efficiently to the VNC
3783 clients). Use this option to disable this behavior.
3784 -wirecopyrect mode, -nowirecopyrect
3786 Since the -wireframe mechanism evidently tracks moving windows
3788 accurately, a speedup can be obtained by telling the VNC viewers
3789 to locally copy the translated window region. This is the VNC
3790 CopyRect encoding: the framebuffer update doesn't need to send
3791 the actual new image data.
3792 Shorter aliases: -wcr [mode] and -nowcr
3794 "mode" can be "never" (same as -nowirecopyrect) to never try the
3796 copyrect, "top" means only do it if the window was not covered
3797 by any other windows, and "always" means to translate the
3798 orginally unobscured region (this may look odd as the remaining
3799 pieces come in, but helps on a slow link). Default: "always"
3800 Note: there can be painting errors or slow response when using
3802 -scale so you may want to disable CopyRect in this case "-wire‐
3803 copyrect never" on the command line or by remote-control. Or
3804 you can also use the "-scale xxx:nocr" scale option.
3805 -debug_wireframe
3807 Turn on debugging info printout for the wireframe heuristics.
3809 "-dwf" is an alias. Specify multiple times for more output.
3810 -scrollcopyrect mode, -noscrollcopyrect
3812 Like -wirecopyrect, but use heuristics to try to guess if a win‐
3814 dow has scrolled its contents (either vertically or horizon‐
3815 tally). This requires the RECORD X extension to "snoop" on X
3816 applications (currently for certain XCopyArea and XConfigureWin‐
3817 dow X protocol requests). Examples: Hitting <Return> in a ter‐
3818 minal window when the cursor was at the bottom, the text scrolls
3819 up one line. Hitting <Down> arrow in a web browser window, the
3820 web page scrolls up a small amount. Or scrolling with a scroll‐
3821 bar or mouse wheel.
3822 Shorter aliases: -scr [mode] and -noscr
3824 This scheme will not always detect scrolls, but when it does
3826 there is a nice speedup from using the VNC CopyRect encoding
3827 (see -wirecopyrect). The speedup is both in reduced network
3828 traffic and reduced X framebuffer polling/copying. On the other
3829 hand, it may induce undesired transients (e.g. a terminal cursor
3830 being scrolled up when it should not be) or other painting
3831 errors (window tearing, bunching-up, etc). These are automati‐
3832 cally repaired in a short period of time. If this is unaccept‐
3833 able disable the feature with -noscrollcopyrect.
3834 Screen clearing kludges: for testing at least, there are some
3836 "magic key sequences" (must be done in less than 1 second) to
3837 aid repairing painting errors that may be seen when using this
3838 mode:
3839 3 Alt_L's in a row: resend whole screen, 4 Alt_L's in a row:
3841 reread and resend whole screen, 3 Super_L's in a row: mark whole
3842 screen for polling, 4 Super_L's in a row: reset RECORD context,
3843 5 Super_L's in a row: try to push a black screen
3844 note: Alt_L is the Left "Alt" key (a single key) Super_L is the
3846 Left "Super" key (Windows flag). Both of these are modifier
3847 keys, and so should not generate characters when pressed by
3848 themselves. Also, your VNC viewer may have its own refresh hot-
3849 key or button.
3850 "mode" can be "never" (same as -noscrollcopyrect) to never try
3852 the copyrect, "keys" means to try it in response to keystrokes
3853 only, "mouse" means to try it in response to mouse events only,
3854 "always" means to do both. Default: "always"
3855 Note: there can be painting errors or slow response when using
3857 -scale so you may want to disable CopyRect in this case
3858 "-scrollcopyrect never" on the command line or by remote-con‐
3859 trol. Or you can also use the "-scale xxx:nocr" scale option.
3860 -scr_area n
3862 Set the minimum area in pixels for a rectangle to be considered
3864 for the -scrollcopyrect detection scheme. This is to avoid
3865 wasting the effort on small rectangles that would be quickly
3866 updated the normal way. E.g. suppose an app updated the posi‐
3867 tion of its skinny scrollbar first and then shifted the large
3868 panel it controlled. We want to be sure to skip the small
3869 scrollbar and get the large panel. Default: 60000
3870 -scr_skip list
3872 Skip scroll detection for applications matching the comma sepa‐
3874 rated list of strings in list. Some applications implement
3875 their scrolling in strange ways where the XCopyArea, etc, also
3876 applies to invisible portions of the window: if we CopyRect
3877 those areas it looks awful during the scroll and there may be
3878 painting errors left after the scroll. Soffice.bin is the worst
3879 known offender.
3880 Use "##" to denote the start of the application class (e.g.
3882 "##XTerm") and "++" to denote the start of the application
3883 instance name (e.g. "++xterm"). The string your list is matched
3884 against is of the form "^^WM_NAME##Class++Instance<same-for-any-
3885 subwindows>" The "xlsclients -la" command will provide this
3886 info.
3887 If a pattern is prefixed with "KEY:" it only applies to Key‐
3889 stroke generated scrolls (e.g. Up arrow). If it is prefixed
3890 with "MOUSE:" it only applies to Mouse induced scrolls (e.g.
3891 dragging on a scrollbar). Default: ##Soffice.bin,##StarOf‐
3892 fice,##OpenOffice
3893 -scr_inc list
3895 Opposite of -scr_skip: this list is consulted first and if there
3897 is a match the window will be monitored via RECORD for scrolls
3898 irrespective of -scr_skip. Use -scr_skip '*' to skip anything
3899 that does not match your -scr_inc. Use -scr_inc '*' to include
3900 everything.
3901 -scr_keys list
3903 For keystroke scroll detection, only apply the RECORD heuristics
3905 to the comma separated list of keysyms in list. You may find
3906 the RECORD overhead for every one of your keystrokes disrupts
3907 typing too much, but you don't want to turn it off completely
3908 with "-scr mouse" and -scr_parms does not work or is too confus‐
3909 ing.
3910 The listed keysyms can be numeric or the keysym names in the
3912 <X11/keysymdef.h> header file or from the xev(1) program. Exam‐
3913 ple: "-scr_keys Up,Down,Return". One probably wants to have
3914 application specific lists (e.g. for terminals, etc) but that is
3915 too icky to think about for now...
3916 If list begins with the "-" character the list is taken as an
3918 exclude list: all keysyms except those list will be considered.
3919 The special string "builtin" expands to an internal list of
3920 keysyms that are likely to cause scrolls. BTW, by default modi‐
3921 fier keys, Shift_L, Control_R, etc, are skipped since they
3922 almost never induce scrolling by themselves.
3923 -scr_term list
3925 Yet another cosmetic kludge. Apply shell/terminal heuristics to
3927 applications matching comma separated list (same as for
3928 -scr_skip/-scr_inc). For example an annoying transient under
3929 scroll detection is if you hit Enter in a terminal shell with
3930 full text window, the solid text cursor block will be scrolled
3931 up. So for a short time there are two (or more) block cursors
3932 on the screen. There are similar scenarios, (e.g. an output
3933 line is duplicated).
3934 These transients are induced by the approximation of scroll
3936 detection (e.g. it detects the scroll, but not the fact that the
3937 block cursor was cleared just before the scroll). In nearly all
3938 cases these transient errors are repaired when the true X frame‐
3939 buffer is consulted by the normal polling. But they are dis‐
3940 tracting, so what this option provides is extra "padding" near
3941 the bottom of the terminal window: a few extra lines near the
3942 bottom will not be scrolled, but rather updated from the actual
3943 X framebuffer. This usually reduces the annoying artifacts.
3944 Use "none" to disable. Default: "term"
3945 -scr_keyrepeat lo-hi
3947 If a key is held down (or otherwise repeats rapidly) and this
3949 induces a rapid sequence of scrolls (e.g. holding down an Arrow
3950 key) the "scrollcopyrect" detection and overhead may not be able
3951 to keep up. A time per single scroll estimate is performed and
3952 if that estimate predicts a sustainable scrollrate of keys per
3953 second between "lo" and "hi" then repeated keys will be DIS‐
3954 CARDED to maintain the scrollrate. For example your key autore‐
3955 peat may be 25 keys/sec, but for a large window or slow link
3956 only 8 scrolls per second can be sustained, then roughly 2 out
3957 of every 3 repeated keys will be discarded during this period.
3958 Default: "4-20"
3959 -scr_parms string
3961 Set various parameters for the scrollcopyrect mode. The format
3963 is similar to that for -wireframe and packed with lots of param‐
3964 eters:
3965 Format: T+B+L+R,t1+t2+t3,s1+s2+s3+s4+s5 Default:
3967 0+64+32+32,0.02+0.10+0.9,0.03+0.06+0.5+0.1+5.0
3968 If you leave nothing between commas: ",," the default value is
3970 used. If you don't specify enough commas, the trailing parame‐
3971 ters are set to their defaults.
3972 "T+B+L+R" indicates four integers for how close in pixels the
3974 pointer has to be from the Top, Bottom, Left, or Right edges of
3975 the window to consider scrollcopyrect. If -wireframe overlaps
3976 it takes precedence. This is a speedup to quickly exclude a
3977 window from being watched for scrollcopyrect: set them all to
3978 zero to not try the speedup (things like selecting text will
3979 likely be slower).
3980 "t1+t2+t3" specify three floating point times in seconds that
3982 apply to scrollcopyrect detection with *Keystroke* input: t1 is
3983 how long to wait after a key is pressed for the first scroll, t2
3984 is how long to keep looking after a Keystroke scroll for more
3985 scrolls. t3 is how frequently to try to update surrounding
3986 scrollbars outside of the scrolling area (0.0 to disable)
3987 "s1+s2+s3+s4+s5" specify five floating point times in seconds
3989 that apply to scrollcopyrect detection with *Mouse* input: s1 is
3990 how long to wait after a mouse button is pressed for the first
3991 scroll, s2 is how long to keep waiting for additional scrolls
3992 after the first Mouse scroll was detected. s3 is how frequently
3993 to try to update surrounding scrollbars outside of the scrolling
3994 area (0.0 to disable). s4 is how long to buffer pointer motion
3995 (to try to get fewer, bigger mouse scrolls). s5 is the maximum
3996 time to spend just updating the scroll window without updating
3997 the rest of the screen.
3998 -fixscreen string
4000 Periodically "repair" the screen based on settings in string.
4002 Hopefully you won't need this option, it is intended for cases
4003 when the -scrollcopyrect or -wirecopyrect features leave too
4004 many painting errors, but it can be used for any scenario. This
4005 option periodically performs costly operations and so interac‐
4006 tive response may be reduced when it is on. You can use 3
4007 Alt_L's (the Left "Alt" key) taps in a row (as described under
4008 -scrollcopyrect) instead to manually request a screen repaint
4009 when it is needed.
4010 string is a comma separated list of one or more of the follow‐
4012 ing: "V=t", "C=t", "X=t", and "8=t". In these "t" stands for a
4013 time in seconds (it is a floating point even though one should
4014 usually use values > 2 to avoid wasting resources). V sets how
4015 frequently the entire screen should be sent to viewers (it is
4016 like the 3 Alt_L's). C sets how long to wait after a CopyRect
4017 to repaint the full screen. X sets how frequently to reread the
4018 full X11 framebuffer from the X server and push it out to con‐
4019 nected viewers. Use of X should be rare, please report a bug if
4020 you find you need it. 8= applies only for -8to24 mode: it sets
4021 how often the non-default visual regions of the screen (e.g.
4022 8bpp windows) are refreshed. Examples: -fixscreen V=10
4023 -fixscreen C=10
4024 -debug_scroll
4026 Turn on debugging info printout for the scroll heuristics.
4028 "-ds" is an alias. Specify it multiple times for more output.
4029 -noxrecord
4031 Disable any use of the RECORD extension. This is currently used
4033 by the -scrollcopyrect scheme and to monitor X server grabs.
4034 -grab_buster, -nograb_buster
4036 Some of the use of the RECORD extension can leave a tiny window
4038 for XGrabServer deadlock. This is only if the whole-server
4039 grabbing application expects mouse or keyboard input before
4040 releasing the grab. It is usually a window manager that does
4041 this. x11vnc takes care to avoid the problem, but if caught
4042 x11vnc will freeze. Without -grab_buster, the only solution is
4043 to go the physical display and give it some input to satisfy the
4044 grabbing app. Or manually kill and restart the window manager
4045 if that is feasible. With -grab_buster, x11vnc will fork a
4046 helper thread and if x11vnc appears to be stuck in a grab after
4047 a period of time (20-30 sec) then it will inject some user
4048 input: button clicks, Escape, mouse motion, etc to try to break
4049 the grab. If you experience a lot of grab deadlock, please
4050 report a bug.
4051 -debug_grabs
4053 Turn on debugging info printout with respect to XGrabServer()
4055 deadlock for -scrollcopyrect__mode_.
4056 -debug_sel
4058 Turn on debugging info printout with respect to PRIMARY, CLIP‐
4060 BOARD, and CUTBUFFER0 selections.
4061 -pointer_mode n
4063 Various pointer motion update schemes. "-pm" is an alias. The
4065 problem is pointer motion can cause rapid changes on the screen:
4066 consider the rapid changes when you drag a large window around
4067 opaquely. Neither x11vnc's screen polling and vnc compression
4068 routines nor the bandwidth to the vncviewers can keep up these
4069 rapid screen changes: everything will bog down when dragging or
4070 scrolling. So a scheme has to be used to "eat" much of that
4071 pointer input before re-polling the screen and sending out
4072 framebuffer updates. The mode number n can be 0 to 4 and selects
4073 one of the schemes desribed below.
4074 Note that the -wireframe and -scrollcopyrect__mode_s complement
4076 -pointer_mode by detecting (and improving) certain periods of
4077 "rapid screen change".
4078 n=0: does the same as -nodragging. (all screen polling is sus‐
4080 pended if a mouse button is pressed.)
4081 n=1: was the original scheme used to about Jan 2004: it basi‐
4083 cally just skips -input_skip keyboard or pointer events before
4084 repolling the screen.
4085 n=2 is an improved scheme: by watching the current rate of input
4087 events it tries to detect if it should try to "eat" additional
4088 pointer events before continuing.
4089 n=3 is basically a dynamic -nodragging mode: it detects when the
4091 mouse motion has paused and then refreshes the display.
4092 n=4 attempts to measures network rates and latency, the video
4094 card read rate, and how many tiles have been changed on the
4095 screen. From this, it aggressively tries to push screen
4096 "frames" when it decides it has enough resources to do so. NOT
4097 FINISHED.
4098 The default n is 2. Note that modes 2, 3, 4 will skip
4100 -input_skip keyboard events (but it will not count pointer
4101 events). Also note that these modes are not available in
4102 -threads mode which has its own pointer event handling mecha‐
4103 nism.
4104 To try out the different pointer modes to see which one gives
4106 the best response for your usage, it is convenient to use the
4107 remote control function, for example "x11vnc -R pm:4" or the
4108 tcl/tk gui (Tuning -> pointer_mode -> n).
4109 -input_skip n
4111 For the pointer handling when non-threaded: try to read n user
4113 input events before scanning display. n < 0 means to act as
4114 though there is always user input. Default: 10
4115 -allinput
4117 Have x11vnc read and process all available client input before
4119 proceeding.
4120 -input_eagerly
4122 Similar to -allinput but use the handleEventsEagerly mechanism
4124 built into LibVNCServer.
4125 -speeds rd,bw,lat
4127 x11vnc tries to estimate some speed parameters that are used to
4129 optimize scheduling (e.g. -pointer_mode 4, -wireframe, -scroll‐
4130 copyrect) and other things. Use the -speeds option to set these
4131 manually. The triple rd,bw,lat corresponds to video h/w read
4132 rate in MB/sec, network bandwidth to clients in KB/sec, and net‐
4133 work latency to clients in milliseconds, respectively. If a
4134 value is left blank, e.g. "-speeds ,100,15", then the internal
4135 scheme is used to estimate the empty value(s).
4136 Typical PC video cards have read rates of 5-10 MB/sec. If the
4138 framebuffer is in main memory instead of video h/w (e.g. SunRay,
4139 shadowfb, dummy driver, Xvfb), the read rate may be much faster.
4140 "x11perf -getimage500" can be used to get a lower bound (remem‐
4141 ber to factor in the bytes per pixel). It is up to you to esti‐
4142 mate the network bandwith and latency to clients. For the
4143 latency the ping(1) command can be used.
4144 For convenience there are some aliases provided, e.g. "-speeds
4146 modem". The aliases are: "modem" for 6,4,200; "dsl" for
4147 6,100,50; and "lan" for 6,5000,1
4148 -wmdt string
4150 For some features, e.g. -wireframe and -scrollcopyrect, x11vnc
4152 has to work around issues for certain window managers or desk‐
4153 tops (currently kde and xfce). By default it tries to guess
4154 which one, but it can guess incorrectly. Use this option to
4155 indicate which wm/dt. string can be "gnome", "kde", "cde",
4156 "xfce", or "root" (classic X wm). Anything else is interpreted
4157 as "root".
4158 -debug_pointer
4160 Print debugging output for every pointer event.
4162 -debug_keyboard
4164 Print debugging output for every keyboard event.
4166 Same as -dp and -dk, respectively. Use multiple times for more output.
4168 -defer time
4170 Time in ms to delay sending updates to connected clients (defer‐
4172 UpdateTime) Default: 20
4173 -wait time
4175 Time in ms to pause between screen polls. Used to cut down on
4177 load. Default: 20
4178 -extra_fbur n
4180 Perform extra FrameBufferUpdateRequests checks to try to be in
4182 better sync with the client's requests. What this does is per‐
4183 form extra polls of the client socket at critical times (before
4184 '-defer' and '-wait' calls.) The default is n=1. Set to a
4185 larger number to insert more checks or set to n=0 to disable. A
4186 downside of these extra calls is that more mouse input may be
4187 processed than desired.
4188 -wait_ui factor
4190 Factor by which to cut the -wait time if there has been recent
4192 user input (pointer or keyboard). Improves response, but
4193 increases the load whenever you are moving the mouse or typing.
4194 Default: 2.00
4195 -setdefer n
4197 When the -wait_ui mechanism cuts down the wait time ms, set the
4199 defer time to the same ms value. n=1 to enable, 0 to disable,
4200 and -1 to set defer to 0 (no delay). Similarly, 2 and -2 indi‐
4201 cate 'urgent_update' mode should be used to push the updates
4202 even sooner. Default: 1
4203 -nowait_bog
4205 Do not detect if the screen polling is "bogging down" and sleep
4207 more. Some activities with no user input can slow things down a
4208 lot: consider a large terminal window with a long build running
4209 in it continuously streaming text output. By default x11vnc
4210 will try to detect this (3 screen polls in a row each longer
4211 than 0.25 sec with no user input), and sleep up to 1.5 secs to
4212 let things "catch up". Use this option to disable that detec‐
4213 tion.
4214 -slow_fb time
4216 Floating point time in seconds to delay all screen polling. For
4218 special purpose usage where a low frame rate is acceptable and
4219 desirable, but you want the user input processed at the normal
4220 rate so you cannot use -wait.
4221 -xrefresh time
4223 Floating point time in seconds to indicate how often to do the
4225 equivalent of xrefresh(1) to force all windows (in the viewable
4226 area if -id, -sid, or -clip is used) to repaint themselves. Use
4227 this only if applications misbehave by not repainting themselves
4228 properly. See also -noxdamage.
4229 -nap, -nonap
4231 Monitor activity and if it is low take longer naps between
4233 screen polls to really cut down load when idle. Default: take
4234 naps
4235 -sb time
4237 Time in seconds after NO activity (e.g. screen blank) to really
4239 throttle down the screen polls (i.e. sleep for about 1.5 secs).
4240 Use 0 to disable. Default: 60 Set the env. var. X11VNC_SB_FAC‐
4241 TOR to scale it.
4242 -readtimeout n
4244 Set LibVNCServer rfbMaxClientWait to n seconds. On slow links
4246 that take a long time to paint the first screen LibVNCServer may
4247 hit the timeout and drop the connection. Default: 20 seconds.
4248 -ping n
4250 Send a 1x1 framebuffer update to all clients every n seconds
4252 (e.g. to try to keep a network connection alive)
4253 -nofbpm, -fbpm
4255 If the system supports the FBPM (Frame Buffer Power Management)
4257 extension (i.e. some Sun systems), then prevent the video h/w
4258 from going into a reduced power state when VNC clients are con‐
4259 nected.
4260 FBPM capable video h/w save energy when the workstation is idle
4262 by going into low power states (similar to DPMS for monitors).
4263 This interferes with x11vnc's polling of the framebuffer data.
4264 "-nofbpm" means prevent FBPM low power states whenever VNC
4266 clients are connected, while "-fbpm" means to not monitor the
4267 FBPM state at all. See the xset(1) manpage for details. -nof‐
4268 bpm is basically the same as running "xset fbpm force on" peri‐
4269 odically. Default: -fbpm
4270 -nodpms, -dpms
4272 If the system supports the DPMS (Display Power Management Sig‐
4274 naling) extension, then prevent the monitor from going into a
4275 reduced power state when VNC clients are connected.
4276 DPMS reduced power monitor states are a good thing and you nor‐
4278 mally want the power down to take place (usually x11vnc has no
4279 problem exporting the display in this state). You probably only
4280 want to use "-nodpms" to work around problems with Screen Savers
4281 kicking on in DPMS low power states. There is known problem
4282 with kdesktop_lock on KDE where the screen saver keeps kicking
4283 in every time user input stops for a second or two. Specifying
4284 "-nodpms" works around it.
4285 "-nodpms" means prevent DPMS low power states whenever VNC
4287 clients are connected, while "-dpms" means to not monitor the
4288 DPMS state at all. See the xset(1) manpage for details.
4289 -nodpms is basically the same as running "xset dpms force on"
4290 periodically. Default: -dpms
4291 -forcedpms
4293 If the system supports the DPMS (Display Power Management Sig‐
4295 naling) extension, then try to keep the monitor in a powered off
4296 state. This is to prevent nosey people at the physical display
4297 from viewing what is on the screen. Be sure to lock the screen
4298 before disconnecting.
4299 This method is far from bullet proof, e.g. suppose someone
4301 attaches a non-DPMS monitor, or loads the machine so that there
4302 is a gap of time before x11vnc restores the powered off state?
4303 On many machines if he floods it with keyboard and mouse input
4304 he can see flashes of what is on the screen before the DPMS off
4305 state is reestablished. For this to work securely there would
4306 need to be support in the X server to do this exactly rather
4307 than approximately with DPMS.
4308 -clientdpms
4310 As -forcedpms but only when VNC clients are connected.
4312 -noserverdpms
4314 The UltraVNC ServerInput extension is supported. This allows
4316 the VNC viewer to click a button that will cause the server
4317 (x11vnc) to try to disable keyboard and mouse input at the phys‐
4318 ical display and put the monitor in dpms powered off state. Use
4319 this option to skip powering off the monitor.
4320 -noultraext
4322 Disable the following UltraVNC extensions: SingleWindow and
4324 ServerInput. The others managed by LibVNCServer (textchat, 1/n
4325 scaling, rfbEncodingUltra) are not.
4326 -chatwindow
4328 Place a local UltraVNC chat window on the X11 display that
4330 x11vnc is polling. That way the person on the VNC viewer-side
4331 can chat with the person at the physical X11 console. (e.g.
4332 helpdesk w/o telephone)
4333 For this to work the SSVNC package (version 1.0.21 or later)
4335 MUST BE installed on the system where x11vnc runs and the
4336 'ssvnc' command must be available in $PATH. The ssvncviewer is
4337 used as a chat window helper. See http://www.karl‐
4338 runge.com/x11vnc/ssvnc.html
4339 This option implies '-rfbversion 3.6' so as to trick UltraVNC
4341 viewers, otherwise they assume chat is not available. To spec‐
4342 ify a different rfbversion, place it after the -chatwindow
4343 option on the cmdline.
4344 See also the remote control 'chaton' and 'chatoff' actions.
4346 These can also be set from the tkx11vnc GUI.
4347 -noxdamage
4349 Do not use the X DAMAGE extension to detect framebuffer changes
4351 even if it is available. Use -xdamage if your default is to
4352 have it off.
4353 x11vnc's use of the DAMAGE extension: 1) significantly reduces
4355 the load when the screen is not changing much, and 2) detects
4356 changed areas (small ones by default) more quickly.
4357 Currently the DAMAGE extension is overly conservative and often
4359 reports large areas (e.g. a whole terminal or browser window) as
4360 damaged even though the actual changed region is much smaller
4361 (sometimes just a few pixels). So heuristics were introduced to
4362 skip large areas and use the damage rectangles only as "hints"
4363 for the traditional scanline polling. The following tuning
4364 parameters are introduced to adjust this behavior:
4365 -xd_area A
4367 Set the largest DAMAGE rectangle area A (in pixels: width *
4369 height) to trust as truly damaged: the rectangle will be copied
4370 from the framebuffer (slow) no matter what. Set to zero to
4371 trust *all* rectangles. Default: 20000
4372 -xd_mem f
4374 Set how long DAMAGE rectangles should be "remembered", f is a
4376 floating point number and is in units of the scanline repeat
4377 cycle time (32 iterations). The default (1.0) should give no
4378 painting problems. Increase it if there are problems or decrease
4379 it to live on the edge (perhaps useful on a slow machine).
4380 -sigpipe string
4382 Broken pipe (SIGPIPE) handling. string can be "ignore" or
4384 "exit". For "ignore" LibVNCServer will handle the abrupt loss
4385 of a client and continue, for "exit" x11vnc will cleanup and
4386 exit at the 1st broken connection.
4387 This option is not really needed since LibVNCServer is doing the
4389 correct thing now for quite some time. However, for convenience
4390 you can use it to ignore other signals, e.g. "-sigpipe
4391 ignore:HUP,INT,TERM" in case that would be useful for some sort
4392 of application. You can also put "exit:.." in the list to have
4393 x11vnc cleanup on the listed signals. "-sig" is an alias for
4394 this option if you don't like the 'pipe'. Example: -sig
4395 ignore:INT,TERM,exit:USR1
4396 -threads, -nothreads
4398 Whether or not to use the threaded LibVNCServer algorithm
4400 [rfbRunEventLoop] if libpthread is available. In this mode new
4401 threads (one for input and one for output) are created to handle
4402 each new client. Default: -nothreads.
4403 Thread stability is much improved in version 0.9.8.
4405 Multiple clients in threaded mode should be stable for the ZRLE
4407 encoding on all platforms. The Tight and Zlib encodings are
4408 currently only stable on Linux for multiple clients. Compile
4409 with -DTLS=__thread if your OS and compiler and linker support
4410 it.
4411 For resizes (randr, etc.) set this env. var. to the number of
4413 milliseconds to sleep: X11VNC_THREADS_NEW_FB_SLEEP at various
4414 places in the do_new_fb() action. This is to let various activ‐
4415 ities settle. Default is about 500ms.
4416 Multiple clients in threaded mode could yield better performance
4418 for 'class-room' broadcasting usage; also in -appshare broadcast
4419 mode. See also the -reflect option.
4420 -fs f
4422 If the fraction of changed tiles in a poll is greater than f,
4424 the whole screen is updated. Default: 0.75
4425 -gaps n
4427 Heuristic to fill in gaps in rows or cols of n or less tiles.
4429 Used to improve text paging. Default: 4
4430 -grow n
4432 Heuristic to grow islands of changed tiles n or wider by check‐
4434 ing the tile near the boundary. Default: 3
4435 -fuzz n
4437 Tolerance in pixels to mark a tiles edges as changed. Default:
4439 2
4440 -debug_tiles
4442 Print debugging output for tiles, fb updates, etc.
4444 -snapfb
4446 Instead of polling the X display framebuffer (fb) for changes,
4448 periodically copy all of X display fb into main memory and exam‐
4449 ine that copy for changes. (This setting also applies for non-X
4450 -rawfb modes). Under some circumstances this will improve
4451 interactive response, or at least make things look smoother, but
4452 in others (most!) it will make the response worse. If the video
4453 h/w fb is such that reading small tiles is very slow this mode
4454 could help. To keep the "framerate" up the screen size x bpp
4455 cannot be too large. Note that this mode is very wasteful of
4456 memory I/O resources (it makes full screen copies even if noth‐
4457 ing changes). It may be of use in video capture-like applica‐
4458 tions, webcams, or where window tearing is a problem.
4459 -rawfb string
4461 Instead of polling X, poll the memory object specified in
4463 string.
4464 For file polling, to memory map mmap(2) a file use:
4466 "map:/path/to/a/file@WxHxB", with framebuffer Width, Height, and
4467 Bits per pixel. "mmap:..." is the same.
4468 If there is trouble with mmap, use "file:/..." for slower
4470 lseek(2) based reading.
4471 Use "snap:..." to imply -snapfb mode and the "file:" access
4473 (this is for unseekable devices that only provide the fb all at
4474 once, e.g. a video camera provides the whole frame).
4475 For shared memory segments string is of the form: "shm:N@WxHxB"
4477 which specifies a shmid N and with WxHxB as above. See shmat(1)
4478 and ipcs(1)
4479 If you do not supply a type "map" is assumed if the file exists
4481 (see the next paragraphs for some exceptions to this.)
4482 If string is "setup:cmd", then the command "cmd" is run and the
4484 first line from it is read and used as string. This allows ini‐
4485 tializing the device, determining WxHxB, etc. These are often
4486 done as root so take care.
4487 If the string begins with "video", see the VIDEO4LINUX discus‐
4489 sion below where the device may be queried for (and possibly
4490 set) the framebuffer parameters.
4491 If the string begins with "console", "/dev/fb", "fb", or "vt",
4493 see the LINUX CONSOLE discussion below where the framebuffer
4494 device is opened and keystrokes (and possibly mouse events) are
4495 inserted into the console.
4496 If the string begins with "vnc", see the VNC HOST discussion
4498 below where the framebuffer is taken as that of another remote
4499 VNC server.
4500 Optional suffixes are ":R/G/B" and "+O" to specify red, green,
4502 and blue masks (in hex) and an offset into the memory object.
4503 If the masks are not provided x11vnc guesses them based on the
4504 bpp (if the colors look wrong, you need to provide the masks.)
4505 Another optional suffix is the Bytes Per Line which in some
4507 cases is not WxB/8. Specify it as WxHxB-BPL e.g.
4508 800x600x16-2048. This could be a normal width 1024 at 16bpp fb,
4509 but only width 800 shows up.
4510 So the full format is: mode:file@WxHxB:R/G/B+O-BPL
4512 Examples:
4514 -rawfb shm:210337933@800x600x32:ff/ff00/ff0000
4516 -rawfb map:/dev/fb0@1024x768x32
4518 -rawfb map:/tmp/Xvfb_screen0@640x480x8+3232
4520 -rawfb file:/tmp/my.pnm@250x200x24+37
4522 -rawfb file:/dev/urandom@128x128x8 -rawfb
4524 snap:/dev/video0@320x240x24 -24to32 -rawfb video0 -rawfb video
4525 -pipeinput VID -rawfb console -rawfb vt2 -rawfb vnc:somehost:0
4526 (see ipcs(1) and fbset(1) for the first two examples)
4528 In general all user input is discarded by default (see the
4530 -pipeinput option for how to use a helper program to insert).
4531 Most of the X11 (screen, keyboard, mouse) options do not make
4532 sense and many will cause this mode to crash, so please think
4533 twice before setting or changing them in a running x11vnc.
4534 If you DO NOT want x11vnc to close the X DISPLAY in rawfb mode,
4536 prepend a "+" e.g. +file:/dev/fb0... Keeping the display open
4537 enables the default remote-control channel, which could be use‐
4538 ful. Alternatively, if you specify -noviewonly, then the mouse
4539 and keyboard input are STILL sent to the X display, this usage
4540 should be very rare, i.e. doing something strange with /dev/fb0.
4541 If the device is not "seekable" (e.g. webcam) try reading it all
4543 at once in full snaps via the "snap:" mode (note: this is a
4544 resource hog). If you are using file: or map: AND the device
4545 needs to be reopened for *every* snapfb snapshot, set the envi‐
4546 ronment variable: SNAPFB_RAWFB_RESET=1 as well.
4547 If you want x11vnc to dynamically transform a 24bpp rawfb to
4549 32bpp (note that this will be slower) also supply the -24to32
4550 option. This would be useful for, say, a video camera that
4551 delivers the pixel data as 24bpp packed RGB. This is the
4552 default under "video" mode if the bpp is 24.
4553 Normally the bits per pixel, B, is 8, 16, or 32 (or rarely 24),
4555 however there is also some support for B < 8 (e.g. old graphics
4556 displays 4 bpp or 1 bpp). In this case you certainly must sup‐
4557 ply the masks as well: WxHxB:R/G/B. The pixels will be padded
4558 out to 8 bpp using depth 8 truecolor. The scheme currently does
4559 not work with snap fb (ask if interested.) B=1 monochrome exam‐
4560 ple: file:/dev/urandom@128x128x1:1/1/1 Some other like this are
4561 128x128x2:3/3/3 128x128x4:7/7/7
4562 For B < 8 framebuffers you can also set the env. var RAWFB_CGA=1
4564 to try a CGA mapping for B=4 (e.g. linux vga16fb driver.) Note
4565 with low bpp and/or resolution VGA and VGA16 modes on the Linux
4566 console one's attempt to export them via x11vnc can often be
4567 thwarted due to special color palettes, pixel packings, and even
4568 video painting buffering. OTOH, often experimenting with the
4569 RGB masks can yield something recognizable.
4570 VIDEO4LINUX: on Linux some attempt is made to handle video
4572 devices (webcams or TV tuners) automatically. The idea is the
4573 WxHxB will be extracted from the device itself. So if you do
4574 not supply "@WxHxB... parameters x11vnc will try to determine
4575 them. It first tries the v4l API if that support has been com‐
4576 piled in. Otherwise it will run the v4l- info(1) external pro‐
4577 gram if it is available.
4578 The simplest examples are "-rawfb video" and "-rawfb video1"
4580 which imply the device file /dev/video and /dev/video1, respec‐
4581 tively. You can also supply the /dev if you like, e.g. "-rawfb
4582 /dev/video0"
4583 Since the video capture device framebuffer usually changes con‐
4585 tinuously (e.g. brightness fluctuations), you may want to use
4586 the -wait, -slow_fb, or -defer options to lower the "framerate"
4587 to cut down on network VNC traffic.
4588 A more sophisticated video device scheme allows initializing the
4590 device's settings using:
4591 -rawfb video:<settings>
4593 The prefix could also be, as above, e.g. "video1:" to specify
4595 the device file. The v4l API must be available for this to
4596 work. Otherwise, you will need to try to initialize the device
4597 with an external program, e.g. xawtv, spcaview, and hope they
4598 persist when x11vnc re-opens the device.
4599 <settings> is a comma separated list of key=value pairs. The
4601 device's brightness, color, contrast, and hue can be set to per‐
4602 centages, e.g. br=80,co=50,cn=44,hu=60.
4603 The device filename can be set too if needed (if it does not
4605 start with "video"), e.g. fn=/dev/qcam.
4606 The width, height and bpp of the framebuffer can be set via,
4608 e.g., w=160,h=120,bpp=16.
4609 Related to the bpp above, the pixel format can be set via the
4611 fmt=XXX, where XXX can be one of: GREY, HI240, RGB555, RGB565,
4612 RGB24, and RGB32 (with bpp 8, 8, 16, 16, 24, and 32 respec‐
4613 tively). See http://www.linuxtv.org for more info (V4L api).
4614 For TV/rf tuner cards one can set the tuning mode via tun=XXX
4616 where XXX can be one of PAL, NTSC, SECAM, or AUTO.
4617 One can switch the input channel by the inp=XXX setting, where
4619 XXX is the name of the input channel (Television, Composite1, S-
4620 Video, etc). Use the name that is in the information about the
4621 device that is printed at startup.
4622 For input channels with tuners (e.g. Television) one can change
4624 which station is selected by the sta=XXX setting. XXX is the
4625 station number. Currently only the ntsc-cable-us (US cable)
4626 channels are built into x11vnc. See the -freqtab option below
4627 to supply one from xawtv. If XXX is greater than 500, then it is
4628 interpreted as a raw frequency in KHz.
4629 Example:
4631 -rawfb video:br=80,w=320,h=240,fmt=RGB32,tun=NTSC,sta=47
4633 one might need to add inp=Television too for the input channel
4635 to be TV if the card doesn't come up by default in that one.
4636 Note that not all video capture devices will support all of the
4638 above settings.
4639 See the -pipeinput VID option below for a way to control the
4641 settings through the VNC Viewer via keystrokes. As a shortcut,
4642 if the string begins "Video.." instead of "video.." then
4643 -pipeinput VID is implied.
4644 As above, if you specify a "@WxHxB..." after the <settings>
4646 string they are used verbatim: the device is not queried for the
4647 current values. Otherwise the device will be queried.
4648 LINUX CONSOLE: The following describes some ways to view and
4650 possibly interact with the Linux text/graphics console (i.e. not
4651 X11 XFree86/Xorg)
4652 Note: If the LibVNCServer LinuxVNC program is on your system you
4654 may want to use that instead of the following method because it
4655 will be faster and more accurate for the Linux text console and
4656 includes mouse support. There is, however, the basic LinuxVNC
4657 functionality in x11vnc if you replace "console" with "vt" in
4658 the examples below.
4659 If the rawfb string begins with "console" the framebuffer device
4661 /dev/fb0 is opened and /dev/tty0 is opened too. The latter is
4662 used to inject keystrokes (not all are supported, but the basic
4663 ones are). You will need to be root to inject keystrokes, but
4664 not necessarily to open /dev/fb0. /dev/tty0 refers to the
4665 active VT, to indicate one explicitly, use, e.g., "console2" for
4666 /dev/tty2, etc. by indicating the specific VT number.
4667 For the Linux framebuffer device, /dev/fb0, (fb1, etc) to be
4669 enabled the appropriate kernel drivers must be loaded. E.g.
4670 vesafb or vga16fb and also by setting the boot parameter
4671 vga=0x301 (or 0x314, 0x317, etc.) (The vga=... method is the
4672 preferred way; set your machines up that way.) Otherwise there
4673 will be a ´No such device' error. You can also load a Linux
4674 framebuffer driver specific to your make of video card for more
4675 functionality. Once the machine is booted one can often 'mod‐
4676 probe' the fb driver as root to obtain a framebuffer device.
4677 If you cannot get /dev/fb0 working on Linux, try using the Lin‐
4679 uxVNC emulation mode by "-rawfb vtN" where N = 1, ... 6 is the
4680 Linux Virtual Terminal (aka virtual console) you wish to view,
4681 e.g. "-rawfb vt2". Unlike /dev/fb mode, it need not be the
4682 active Virtual Terminal. Note that this mode can only show text
4683 and not graphics. x11vnc polls the text in /dev/vcsaN
4684 Set the env. var. RAWFB_VCSA_BW=1 to disable colors in the "vtN"
4686 mode (i.e. black and white only.) If you do not prefer the
4687 default 16bpp set RAWFB_VCSA_BPP to 8 or 32. If you need to
4688 tweak the rawfb parameters by using the 'console_guess' string
4689 printed at startup, be sure to indicate the snap: method.
4690 uinput: If the Linux version appears to be 2.6 or later and the
4692 "uinput" module appears to be present (modprobe uinput), then
4693 the uinput method will be used instead of /dev/ttyN. uinput
4694 allows insertion of BOTH keystrokes and mouse input and so it
4695 preferred when accessing graphical (e.g. QT-embedded) linux con‐
4696 sole apps. It also provides more accurate keystroke insertion.
4697 See -pipeinput UINPUT below for more information on this mode;
4698 you will have to use -pipeinput if you want to tweak any UINPUT
4699 parameters. You may also want to also use the -nodragging and
4700 -cursor none options. Use "console0", etc or -pipeinput CON‐
4701 SOLE to force the /dev/ttyN method.
4702 Note you can change the Linux VT remotely using the chvt(1) com‐
4704 mand to make the one you want be the active one (e.g. 'chvt 3').
4705 Sometimes switching out and back corrects the framebuffer's
4706 graphics state. For the "-rawfb vtN" mode there is no need to
4707 switch the VT's.
4708 To skip input injecting entirely use "consolex" or "vtx".
4710 The string "/dev/fb0" (1, etc.) can be used instead of "con‐
4712 sole". This can be used to specify a different framebuffer
4713 device, e.g. /dev/fb1. As a shortcut the "/dev/" can be
4714 dropped. If the name is something nonstandard, use "con‐
4715 sole:/dev/foofb"
4716 If you do not want x11vnc to guess the framebuffer's WxHxB and
4718 masks automatically (sometimes the kernel gives incorrect infor‐
4719 mation), specify them with a @WxHxB (and optional :R/G/B masks)
4720 at the end of the string.
4721 Examples: -rawfb console -rawfb /dev/fb0 (same) -rawfb
4723 console3 (force /dev/tty3) -rawfb consolex
4724 (no keystrokes or mouse) -rawfb console:/dev/nonstd -rawfb con‐
4725 sole -pipeinput UINPUT:accel=4.0 -rawfb vt3
4726 (/dev/tty3 w/o /dev/fb0)
4727 VNC HOST: if the -rawfb string is of the form "vnc:host:N" then
4729 the VNC display "N" on the remote VNC server "host" is connected
4730 to (i.e. x11vnc acts as a VNC client itself) and that frame‐
4731 buffer is exported. This is the same as the option "-reflect
4732 host:N".
4733 This mode is really only of use if you are trying to improve
4735 performance in the case of many (e.g. >10) simultaneous VNC
4736 viewers, and you try a divide and conquer scheme to reduce band‐
4737 width and improve responsiveness. However, another user found
4738 this mode useful to export a demo display through a slow link:
4739 then multiple demo viewers connected to the reflecting x11vnc on
4740 the fast side of the link, and so avoided all of the demo view‐
4741 ers going through the slow link. Other users have found this
4742 mode useful to be able to take advantage of some of x11vnc's
4743 many features that other VNC servers do not have, for example
4744 SSL encryption, single port http and https, unix usernames and
4745 passwords, and -allow, -zeroconf, -clip, and -scale options and
4746 others.
4747 For the classroom broadcast example, if there will be 64 simul‐
4749 taneous VNC viewers this can lead to a lot of redundant VNC
4750 traffic to and from the server host:N, extra CPU usage, and all
4751 viewers response can be reduced by having to wait for writes to
4752 the slowest client to finish. However, if you set up 8 reflec‐
4753 tors/repeaters started with option -rawfb vnc:host:N, then there
4754 are only 8 connections to host:N. Each repeater then handles 8
4755 vnc viewer connections thereby spreading the load around. In
4756 classroom broadcast usage, try to put the repeaters on different
4757 switches. This mode is the same as -reflect host:N. Replace
4758 "host:N" by "listen" or "listen:port" for a reverse connection.
4759 Use "listennofork:port" to use the LibVNCServer non forking
4760 client listen interface (if your LibVNCServer has it), same as
4761 setting X11VNC_REFLECT_NO_FORK=1.
4762 Overall performance will not be as good as a single direct con‐
4764 nection because, among other things, there is an additional
4765 level of framebuffer polling and pointer motion can still induce
4766 many changes per second that must be propagated. Tip: if the
4767 remote VNC is x11vnc doing wireframing, or an X display that
4768 does wireframing that gives much better response than opaque
4769 window dragging. Consider the -nodragging option if the problem
4770 is severe.
4771 The env. var. X11VNC_REFLECT_PASSWORD can be set to the password
4773 needed to log into the vnc host server, or to
4774 "file:path_to_file" to indicate a file containing the password
4775 as its first line.
4776 To set the pixel format that x11vnc requests as a VNC CLIENT set
4778 the env. vars: X11VNC_REFLECT_bitsPerSample X11VNC_REFLECT_sam‐
4779 plesPerPixel, and X11VNC_REFLECT_bytesPerPixel; the defaults are
4780 8, 3, 4. 2, 3, 1 would give a low color mode. See the function
4781 rfbGetClient() in libvncclient for more info.
4782 The VNC HOST mode implies -shared. Use -noshared as a subse‐
4784 quent cmdline option to disable sharing.
4785 -freqtab file
4787 For use with "-rawfb video" for TV tuner devices to specify sta‐
4789 tion frequencies. Instead of using the built in ntsc-cable-us
4790 mapping of station number to frequency, use the data in file.
4791 For stations that are not numeric, e.g. SE20, they are placed
4792 above the highest numbered station in the order they are found.
4793 Example: "-freqtab /usr/X11R6/share/xawtv/europe-west.list" You
4794 can make your own freqtab by copying the xawtv format.
4795 -pipeinput cmd
4797 This option lets you supply an external command in cmd that
4799 x11vnc will pipe all of the user input events to in a simple
4800 format. In -pipeinput mode by default x11vnc will not process
4801 any of the user input events. If you prefix cmd with "tee:" it
4802 will both send them to the pipe command and process them. For a
4803 description of the format run "-pipeinput tee:/bin/cat".
4804 Another prefix is "reopen" which means to reopen pipe if it
4805 exits. Separate multiple prefixes with commas.
4806 In combination with -rawfb one might be able to do amusing
4808 things (e.g. control non-X devices). To facilitate this, if
4809 -rawfb is in effect then the value is stored in X11VNC_RAWFB_STR
4810 for the pipe command to use if it wants. Do 'env | grep X11VNC'
4811 for more.
4812 Built-in pipeinput modes (no external program required):
4814 If cmd is "VID" and you are using the -rawfb for a video capture
4816 device, then an internal list of keyboard mappings is used to
4817 set parameters of the video. The mappings are:
4818 "B" and "b" adjust the brightness up and down. "H" and "h"
4820 adjust the hue. "C" and "c" adjust the colour. "N" and "n"
4821 adjust the contrast. "S" and "s" adjust the size of the capture
4822 screen. "I" and "i" cycle through input channels. Up and Down
4823 arrows adjust the station (if a tuner) F1, F2, ..., F6 will
4824 switch the video capture pixel format to HI240, RGB565, RGB24,
4825 RGB32, RGB555, and GREY respectively. See -rawfb video for
4826 details.
4827 If cmd is "CONSOLE" or "CONSOLEn" where n is a Linux console
4829 number, then the linux console keystroke insertion to /dev/ttyN
4830 (see -rawfb console) is performed.
4831 If cmd begins with "UINPUT" then the Linux uinput module is used
4833 to insert both keystroke and mouse events to the Linux console
4834 (see -rawfb above). This usually is the /dev/input/uinput
4835 device file (you may need to create it with "mknod
4836 /dev/input/uinput c 10 223" and insert the module with "modprobe
4837 uinput".
4838 The UINPUT mode currently only does US keyboards (a scan code
4840 option may be added), and not all keysyms are supported. But it
4841 is probably more accurate than the "CONSOLE" method.
4842 You may want to use the options -cursor none and -nodragging in
4844 this mode.
4845 Additional tuning options may be supplied via: UIN‐
4847 PUT:opt1,opt2,... (a comma separated list). If an option begins
4848 with "/" it is taken as the uinput device file.
4849 Which uinput is injected can be controlled by an option string
4851 made of the characters "K", "M", and "B" (see the -input
4852 option), e.g. "KM" allows keystroke and motion but not button
4853 clicks.
4854 A UINPUT option of the form: accel=f, or accel=fx+fy sets the
4856 mouse motion "acceleration". This is used to correct raw mouse
4857 relative motion into how much the application cursor moves
4858 (x11vnc has no control over, or knowledge of how the windowing
4859 application interprets the raw mouse motions). Typically the
4860 acceleration for an X display is 2 (see xset "m" option). "f"
4861 is a floating point number, e.g. 3.0. Use "fx+fy" if you need
4862 to supply different corrections for x and y.
4863 Note: the default acceleration is 2.0 since it seems both X and
4865 qt-embedded often (but not always) use this value.
4866 Even with a correct accel setting the mouse position will get
4868 out of sync (probably due to a mouse "threshold" setting where
4869 the acceleration doe not apply, set xset(1) ). The option
4870 reset=N sets the number of ms (default 150) after which the cur‐
4871 sor is attempted to be reset (by forcing the mouse to (0, 0) via
4872 small increments and then back out to (x, y) in 1 jump), This
4873 correction seems to be needed but can cause jerkiness or unex‐
4874 pected behavior with menus, etc. Use reset=0 to disable.
4875 If you set the env. var X11VNC_UINPUT_THRESHOLDS then the
4877 thresh=n mode will be enabled. It is currently not working
4878 well. If |dx| <= thresh and |dy| < thresh no acceleration is
4879 applied. Use "thresh=+n" |dx| + |dy| < thresh to be used
4880 instead (X11?)
4881 Example: -pipeinput UINPUT:accel=4.0 -cursor none
4883 If the uinput device has an absolute pointer (as opposed to a
4885 normal mouse that is a relative pointer) you can specify the
4886 option "abs". Note that a touchpad on a laptop is an absolute
4887 device to some degree. This (usually) avoids all the problems
4888 with mouse acceleration. If x11vnc has trouble deducing the
4889 size of the device, use "abs=WxH". Furthermore, if the device
4890 is a touchscreen (assumed to have an absolute pointer) use
4891 "touch" or "touch=WxH". For touchscreens, when a mouse button
4892 is pressed, a pressure increase is injected, and when the button
4893 is released a pressure of zero is injected.
4894 If touch has been set, use "touch_always=1" to indicate whenever
4896 the mouse moves with no button pressed, a touch event of zero
4897 pressure should be sent anyway. Also use "btn_touch=1" to indi‐
4898 cate a BTN_TOUCH keystroke press or release should be sent
4899 instead of a pressure change. Set "dragskip=n" to skip n
4900 dragged mouse touches (with pressure applied) before injecting
4901 one. To indicate the pressure that should be sent when there is
4902 a button click for a touchscreen device, specify pressure=n,
4903 e.g. n=5. The default is n=1.
4904 If a touch screen is being used ("touch" above) and it is having
4906 its input processed by tslib, you can specify the tslib calibra‐
4907 tion file via tslib_cal=<file>. For example,
4908 tslib_cal=/etc/pointercal. To get accurate or even usable posi‐
4909 tioning this is required when tslib is in use.
4910 The Linux uinput mechanism can be bypassed and one can write
4912 input events DIRECTLY to the devices instead. To do this, spec‐
4913 ify one or more of the following for the input classes:
4914 direct_rel=<device> direct_abs=<device> direct_btn=<device> or
4915 direct_key=<device>. The <device> file is usually something
4916 like /dev/input/event1 but you can specify any device file or
4917 pipe. You must specify each one of the above classes even if
4918 they correspond to the same device file (rel/abs and btn are
4919 often the same.) Look at the file /proc/bus/input/devices to
4920 get an idea what is available and the device filenames. Note:
4921 The /dev/input/mouse* devices do not seem to work, use the cor‐
4922 responding /dev/input/event* file instead. Any input class not
4923 directly specified as above will be handled via the uinput mech‐
4924 anism. To disable creating a uinput device (and thereby dis‐
4925 carding unhandled input), specify "nouinput".
4926 Examples:
4928 -pipeinput UINPUT:direct_abs=/dev/input/event1
4930 this was used on a qtmoko Neo freerunner (armel):
4932 -pipeinput UINPUT:touch,tslib_cal=/etc/pointercal,
4934 direct_abs=/dev/input/event1,nouinput,dragskip=4
4935 (where the long line has been split into two.)
4937 You can set the env. var X11VNC_UINPUT_DEBUG=1 or higher to get
4939 debugging output for UINPUT mode.
4940 -macnodim
4942 For the native MacOSX server, disable dimming.
4944 -macnosleep
4946 For the native MacOSX server, disable display sleep.
4948 -macnosaver
4950 For the native MacOSX server, disable screensaver.
4952 -macnowait
4954 For the native MacOSX server, do not wait for the user to switch
4956 back to his display.
4957 -macwheel n
4959 For the native MacOSX server, set the mouse wheel speed to n
4961 (default 5).
4962 -macnoswap
4964 For the native MacOSX server, do not swap mouse buttons 2 and 3.
4966 -macnoresize
4968 For the native MacOSX server, do not resize or reset the frame‐
4970 buffer even if it is detected that the screen resolution or
4971 depth has changed.
4972 -maciconanim n
4974 For the native MacOSX server, set n to the number of millisec‐
4976 onds that the window iconify/deiconify animation takes. In
4977 -ncache mode this value will be used to skip the animation if
4978 possible. (default 400)
4979 -macmenu
4981 For the native MacOSX server, in -ncache client-side caching
4983 mode, try to cache pull down menus (not perfect because they
4984 have animated fades, etc.)
4985 -macuskbd
4987 For the native MacOSX server, use the original keystroke inser‐
4989 tion code based on a US keyboard.
4990 -macnocglion
4992 For the native MacOSX server, do not use CG interfaces added for
4994 MacOSX Lion for screen capture.
4995 -macnoopengl
4997 For the native MacOSX server, do not use OpenGL for screen cap‐
4999 ture.
5000 -macnorawfb
5002 For the native MacOSX server, disable the raw memory address
5004 screen capture method.
5005 -macdisplay n
5007 For the native MacOSX server, use display 'n' as the screen to
5009 export. A macosx display is a distinct monitor or builtin
5010 screen. The main display is always n=0 and is the default
5011 screen to export. For an extra attached monitor use n=1, etc.
5012 A list of all Available Displays is printed out at startup so
5013 that you can find the n you want. Notes: Currently there seem
5014 to be refresh problems with anything but the main display. Not
5015 all of the pointer behavior is correct in the non-main displays.
5016 Usually only the main display has the menu bar (so you may need
5017 to run a more than one x11vnc for complete control of an appli‐
5018 cation.)
5019 MORE MACOSX NOTES: There are some deprecated MacOSX interfaces
5021 to inject keyboard and mouse events and the raw memory access
5022 method is deprecated as well (however, OpenGL will be preferred
5023 if available because it is faster.) One can force not using any
5024 deprecated interfaces at compile time by setting
5025 -DX11VNC_MACOSX_NO_DEPRECATED=1 in CPPFLAGS. Or to turn them
5026 off one by one: -DX11VNC_MACOSX_NO_DEPRECATED_LOCALEVENTS=1,
5027 -DX11VNC_MACOSX_NO_DEPRECATED_POSTEVENTS=1 or
5028 -DX11VNC_MACOSX_NO_DEPRECATED_FRAMEBUFFER=1 At run time, for
5029 testing and workarounds, one can disable them by using: -env
5030 X11VNC_MACOSX_NO_DEPRECATED=1 -env X11VNC_MACOSX_NO_DEPRE‐
5031 CATED_LOCALEVENTS=1 -env X11VNC_MACOSX_NO_DEPRE‐
5032 CATED_POSTEVENTS=1 or -env X11VNC_MACOSX_NO_DEPRECATED_FRAME‐
5033 BUFFER=1 Note: When doing either of these for the mouse input
5034 not everything works currently, e.g. double clicks and wirefram‐
5035 ing. Also, screen resolution and pixel depth changes will not
5036 be automatically detected unless the deprecated framebuffer
5037 interfaces are allowed.
5038 Conversely, if you are compiling on an older machine that does
5040 not have some of the newer interfaces, you may need to specify
5041 -DX11VNC_MACOSX_NO_CGEVENTCREATESCROLLWHEELEVENT
5042 -DX11VNC_MACOSX_NO_CGEVENTCREATEMOUSEEVENT or
5043 -DX11VNC_MACOSX_NO_CGEVENTCREATEKEYBOARDEVENT. Use
5044 -DX11VNC_MACOSX_USE_GETMAINDEVICE to regain the very old Quick‐
5045 Draw GetMainDevice() interface (rare...) End of MACOSX NOTES.
5046 -gui [gui-opts]
5048 Start up a simple tcl/tk gui based on the remote control options
5050 -remote/-query described below. Requires the "wish" program to
5051 be installed on the machine. "gui-opts" is not required: the
5052 default is to start up both the full gui and x11vnc with the gui
5053 showing up on the X display in the environment variable DISPLAY.
5054 "gui-opts" can be a comma separated list of items. Currently
5056 there are these types of items: 1) a gui mode, a 2) gui "sim‐
5057 plicity", 3) the X display the gui should display on, 4) a
5058 "tray" or "icon" mode, and 5) a gui geometry.
5059 1) The gui mode can be "start", "conn", or "wait" "start" is the
5061 default mode above and is not required. "conn" means do not
5062 automatically start up x11vnc, but instead just try to connect
5063 to an existing x11vnc process. "wait" means just start the gui
5064 and nothing else (you will later instruct the gui to start
5065 x11vnc or connect to an existing one.)
5066 2) The gui simplicity is off by default (a power-user gui with
5068 all options is presented) To start with something less daunting
5069 supply the string "simple" ("ez" is an alias for this). Once
5070 the gui is started you can toggle between the two with "Misc ->
5071 simple_gui".
5072 3) Note the possible confusion regarding the potentially two
5074 different X displays: x11vnc polls one, but you may want the gui
5075 to appear on another. For example, if you ssh in and x11vnc is
5076 not running yet you may want the gui to come back to you via
5077 your ssh redirected X display (e.g. localhost:10).
5078 If you do not specify a gui X display in "gui-opts" then the
5080 DISPLAY environment variable and -display option are tried (in
5081 that order). Regarding the x11vnc X display the gui will try to
5082 communication with, it first tries -display and then DISPLAY.
5083 For example, "x11vnc -display :0 -gui otherhost:0", will remote
5084 control an x11vnc polling :0 and display the gui on otherhost:0
5085 The "tray/icon" mode below reverses this preference, preferring
5086 to display on the x11vnc display.
5087 4) When "tray" or "icon" is specified, the gui presents itself
5089 as a small icon with behavior typical of a "system tray" or
5090 "dock applet". The color of the icon indicates status (con‐
5091 nected clients) and there is also a balloon status. Clicking on
5092 the icon gives a menu from which properties, etc, can be set and
5093 the full gui is available under "Advanced". To be fully func‐
5094 tional, the gui mode should be "start" (the default).
5095 Note that tray or icon mode will imply the -forever x11vnc
5097 option (if the x11vnc server is started along with the gui)
5098 unless -connect or -connect_or_exit has been specified. So
5099 x11vnc (and the tray/icon gui) will wait for more connections
5100 after the first client disconnects. If you want only one viewer
5101 connection include the -once option.
5102 For "icon" the gui just a small standalone window. For "tray"
5104 it will attempt to embed itself in the "system tray" if possi‐
5105 ble. If "=setpass" is appended then at startup the X11 user will
5106 be prompted to set the VNC session password. If =<hexnumber> is
5107 appended that icon will attempt to embed itself in the window
5108 given by hexnumber. Use =noadvanced to disable the full gui.
5109 (To supply more than one, use "+" sign). E.g. -gui tray=setpass
5110 and -gui icon=0x3600028
5111 Other modes: "full", the default and need not be specified.
5113 "-gui none", do not show a gui, useful to override a ~/.x11vncrc
5114 setting, etc.
5115 5) When "geom=+X+Y" is specified, that geometry is passed to the
5117 gui toplevel. This is the icon in icon/tray mode, or the full
5118 gui otherwise. You can also specify width and height, i.e.
5119 WxH+X+Y, but it is not recommended. In "tray" mode the geometry
5120 is ignored unless the system tray manager does not seem to be
5121 running. One could imagine using something like "-gui
5122 tray,geom=+4000+4000" with a display manager to keep the gui
5123 invisible until someone logs in...
5124 More icon tricks, "icon=minimal" gives an icon just with the VNC
5126 display number. You can also set the font with "iconfont=...".
5127 The following could be useful: "-gui icon=minimal,icon‐
5128 font=5x8,geom=24x10+0-0"
5129 General examples of the -gui option: "x11vnc -gui", "x11vnc -gui
5131 ez" "x11vnc -gui localhost:10", "x11vnc -gui conn,host:0",
5132 "x11vnc -gui tray,ez" "x11vnc -gui tray=setpass"
5133 If you do not intend to start x11vnc from the gui (i.e. just
5135 remote control an existing one), then the gui process can run on
5136 a different machine from the x11vnc server as long as X permis‐
5137 sions, etc. permit communication between the two.
5138 FONTS: On some systems the tk fonts can be too small, jagged, or
5140 otherwise unreadable. There are 4 env vars you can set to be
5141 the tk font you prefer:
5142 X11VNC_FONT_BOLD main font for menus and buttons.
5144 X11VNC_FONT_FIXED font for fixed width text.
5145 X11VNC_FONT_BOLD_SMALL tray icon font. X11VNC_FONT_REG_SMALL
5147 tray icon menu font.
5148 The last two only apply for the tray icon mode.
5150 Here are some examples:
5152 -env X11VNC_FONT_BOLD='Helvetica -16 bold' -env
5154 X11VNC_FONT_FIXED='Courier -14' -env X11VNC_FONT_REG_SMALL='Hel‐
5155 vetica -12'
5156 You can put the lines like the above (without the quotes) in
5158 your ~/.x11vncrc file to avoid having to specify them on the
5159 x11vnc command line.
5160 Sometimes there are problems when the gui asks x11vnc to use the
5162 identd (port 113) service to try to get the names of attached
5163 users. To disable trying to connect to the viewer machines to
5164 identify the user's names, set -env X11VNC_NO_IDENT_USERNAME=1
5165 -remote command
5167 Remotely control some aspects of an already running x11vnc
5169 server. "-R" and "-r" are aliases for "-remote". After the
5170 remote control command is sent to the running server the 'x11vnc
5171 -remote ...' x11vnc command exits. You can often use the
5172 -query command (see below) to see if the x11vnc server processed
5173 your -remote command.
5174 The default communication channel is that of X properties
5176 (specifically X11VNC_REMOTE), and so this command must be run
5177 with correct settings for DISPLAY and possibly XAUTHORITY to
5178 connect to the X server and set the property. Alternatively,
5179 use the -display and -auth options to set them to the correct
5180 values. The running server cannot use the -novncconnect option
5181 because that disables the communication channel. See below for
5182 alternate channels.
5183 For example: 'x11vnc -remote stop' (which is the same as ´x11vnc
5185 -R stop') will close down the x11vnc server. ´x11vnc -R shared'
5186 will enable shared connections, and ´x11vnc -R scale:3/4' will
5187 rescale the desktop.
5188 To use a different name for the X11 property (e.g. to have sepa‐
5190 rate communication channels for multiple x11vnc's on the same
5191 display) set the X11VNC_REMOTE environment variable to the
5192 string you want, for example: -env
5193 X11VNC_REMOTE=X11VNC_REMOTE_12345 Both sides of the channel must
5194 use the same unique name.
5195 To run a bunch of commands in a sequence use something like:
5197 x11vnc -R 'script:firstcmd;secondcmd;...'
5198 Use x11vnc -R script:file=/path/to/file to read commands from a
5200 file (can be multi-line and use the comment '#' character in the
5201 normal way. The ';' separator must still be used to separate
5202 each command.)
5203 To not try to contact another x11vnc process and instead just
5205 run the command (or query) directly, prefix the command with the
5206 string "DIRECT:"
5207 The following -remote/-R commands are supported:
5209 stop terminate the server, same as "quit" "exit" or
5211 "shutdown".
5212 ping see if the x11vnc server responds. return is:
5214 ans=ping:<display>
5215 ping:mystring as above, but use your own unique string.
5217 return is: ans=ping:mystring:<xdisplay>
5218 blacken try to push a black fb update to all clients
5220 (due to timings a client could miss it). Same as "zero", also
5221 "zero:x1,y1,x2,y2" for a rectangle.
5222 refresh send the entire fb to all clients.
5224 reset recreate the fb, polling memory, etc.
5226 id:windowid set -id window to "windowid". empty or "root" to
5228 go back to root window
5229 sid:windowid set -sid window to "windowid"
5231 id_cmd:cmd cmds: raise, lower, map, unmap, iconify,
5233 move:dXdY, resize:dWdH, geom:WxH+X+Y. dX dY, dW, and dH must
5234 have a leading "+" or "-" e.g.: move:-30+10 resize:+20+35 also:
5235 wm_delete, wm_name:string and icon_name:string. Also
5236 id_cmd:win=N:cmd
5237 waitmapped wait until subwin is mapped.
5239 nowaitmapped do not wait until subwin is mapped.
5241 clip:WxH+X+Y set -clip mode to "WxH+X+Y"
5243 flashcmap enable -flashcmap mode.
5245 noflashcmap disable -flashcmap mode.
5247 shiftcmap:n set -shiftcmap to n.
5249 notruecolor enable -notruecolor mode.
5251 truecolor disable -notruecolor mode.
5253 overlay enable -overlay mode (if applicable).
5255 nooverlay disable -overlay mode.
5257 overlay_cursor in -overlay mode, enable cursor drawing.
5259 overlay_nocursor disable cursor drawing. same as nooverlay_cur‐
5261 sor.
5262 8to24 enable -8to24 mode (if applicable).
5264 no8to24 disable -8to24 mode.
5266 8to24_opts:str set the -8to24 opts to "str".
5268 24to32 enable -24to32 mode (if applicable).
5270 no24to32 disable -24to32 mode.
5272 visual:vis set -visual to "vis"
5274 scale:frac set -scale to "frac"
5276 scale_cursor:f set -scale_cursor to "f"
5278 viewonly enable -viewonly mode.
5280 noviewonly disable -viewonly mode.
5282 shared enable -shared mode.
5284 noshared disable -shared mode.
5286 forever enable -forever mode.
5288 noforever disable -forever mode.
5290 timeout:n reset -timeout to n, if there are currently no
5292 clients, exit unless one connects in the next n secs.
5293 tightfilexfer enable filetransfer for NEW clients.
5295 notightfilexfer disable filetransfer for NEW clients.
5297 ultrafilexfer enable filetransfer for clients.
5299 noultrafilexfer disable filetransfer for clients.
5301 rfbversion:n.m set -rfbversion for new clients.
5303 http enable http client connections.
5305 nohttp disable http client connections.
5307 deny deny any new connections, same as "lock"
5309 nodeny allow new connections, same as "unlock"
5311 avahi enable avahi service advertising.
5313 noavahi disable avahi service advertising.
5315 mdns enable avahi service advertising.
5317 nomdns disable avahi service advertising.
5319 zeroconf enable avahi service advertising.
5321 nozeroconf disable avahi service advertising.
5323 connect:host do reverse connection to host, "host" may be a
5325 comma separated list of hosts or host:ports. See -connect.
5326 Passwords required as with fwd connections. See
5327 X11VNC_REVERSE_CONNECTION_NO_AUTH=1
5328 disconnect:host disconnect any clients from "host" same as
5330 "close:host". Use host "all" to close all current clients. If
5331 you know the client internal hex ID, e.g. 0x3 (returned by
5332 "-query clients" and RFB_CLIENT_ID) you can use that too.
5333 proxy:host:port set reverse connection proxy (empty to disable).
5335 allowonce:host For the next connection only, allow connection
5337 from "host". In -ssl mode two connections are allowed (i.e.
5338 Fetch Cert) unless X11VNC_NO_SSL_ALLOW_TWICE=1
5339 allow:hostlist set -allow list to (comma separated) "hostlist".
5341 See -allow and -localhost. Do not use with -allow /path/to/file
5342 Use "+host" to add a single host, and use "-host" to delete a
5343 single host
5344 localhost enable -localhost mode
5346 nolocalhost disable -localhost mode
5348 listen:str set -listen to str, empty to disable.
5350 noipv6 enable -noipv6 mode.
5352 ipv6 disable -noipv6 mode.
5354 noipv4 enable -noipv4 mode.
5356 ipv4 disable -noipv4 mode.
5358 6 enable -6 IPv6 listening mode.
5360 no6 disable -6 IPv6 listening mode.
5362 lookup disable -nolookup mode.
5364 nolookup enable -nolookup mode.
5366 lookup disable -nolookup mode.
5368 input:str set -input to "str", empty to disable.
5370 grabkbd enable -grabkbd mode.
5372 nograbkbd disable -grabkbd mode.
5374 grabptr enable -grabptr mode.
5376 nograbptr disable -grabptr mode.
5378 grabalways enable -grabalways mode.
5380 nograbalways disable -grabalways mode.
5382 grablocal:n set -grablocal to n.
5384 client_input:str set the K, M, B -input on a per-client basis.
5386 select which client as for disconnect, e.g. client_input:host:MB
5387 or client_input:0x2:K
5388 accept:cmd set -accept "cmd" (empty to disable).
5390 afteraccept:cmd set -afteraccept (empty to disable).
5392 gone:cmd set -gone "cmd" (empty to disable).
5394 noshm enable -noshm mode.
5396 shm disable -noshm mode (i.e. use shm).
5398 flipbyteorder enable -flipbyteorder mode, you may need to set
5400 noshm for this to do something.
5401 noflipbyteorder disable -flipbyteorder mode.
5403 onetile enable -onetile mode. (you may need to set shm
5405 for this to do something)
5406 noonetile disable -onetile mode.
5408 solid enable -solid mode
5410 nosolid disable -solid mode.
5412 solid_color:color set -solid color (and apply it).
5414 blackout:str set -blackout "str" (empty to disable). See
5416 -blackout for the form of "str" (basically: WxH+X+Y,...) Use
5417 "+WxH+X+Y" to append a single rectangle use "-WxH+X+Y" to delete
5418 one
5419 xinerama enable -xinerama mode. (if applicable)
5421 noxinerama disable -xinerama mode.
5423 xtrap enable -xtrap input mode(if applicable)
5425 noxtrap disable -xtrap input mode.
5427 xrandr enable -xrandr mode. (if applicable)
5429 noxrandr disable -xrandr mode.
5431 xrandr_mode:mode set the -xrandr mode to "mode".
5433 rotate:mode set the -rotate mode to "mode".
5435 padgeom:WxH set -padgeom to WxH (empty to disable) If WxH is
5437 "force" or "do" the padded geometry fb is immediately applied.
5438 quiet enable -quiet mode.
5440 noquiet disable -quiet mode.
5442 modtweak enable -modtweak mode.
5444 nomodtweak enable -nomodtweak mode.
5446 xkb enable -xkb modtweak mode.
5448 noxkb disable -xkb modtweak mode.
5450 capslock enable -capslock mode.
5452 nocapslock disable -capslock mode.
5454 skip_lockkeys enable -skip_lockkeys mode.
5456 noskip_lockkeys disable -skip_lockkeys mode.
5458 skip_keycodes:str enable -xkb -skip_keycodes "str".
5460 sloppy_keys enable -sloppy_keys mode.
5462 nosloppy_keys disable -sloppy_keys mode.
5464 skip_dups enable -skip_dups mode.
5466 noskip_dups disable -skip_dups mode.
5468 add_keysyms enable -add_keysyms mode.
5470 noadd_keysyms stop adding keysyms. those added will still be
5472 removed at exit.
5473 clear_mods enable -clear_mods mode and clear them.
5475 noclear_mods disable -clear_mods mode.
5477 clear_keys enable -clear_keys mode and clear them.
5479 noclear_keys disable -clear_keys mode.
5481 clear_locks do the clear_locks action.
5483 clear_all do the clear_all action.
5485 keystate have x11vnc print current keystate.
5487 remap:str set -remap "str" (empty to disable). See -remap
5489 for the form of "str" (basically: key1-key2,key3-key4,...) Use
5490 "+key1-key2" to append a single keymapping, use "-key1-key2" to
5491 delete.
5492 norepeat enable -norepeat mode.
5494 repeat disable -norepeat mode.
5496 nofb enable -nofb mode.
5498 fb disable -nofb mode.
5500 bell enable bell (if supported).
5502 nobell disable bell.
5504 sendbell ring the bell now.
5506 nosel enable -nosel mode.
5508 sel disable -nosel mode.
5510 noprimary enable -noprimary mode.
5512 primary disable -noprimary mode.
5514 nosetprimary enable -nosetprimary mode.
5516 setprimary disable -nosetprimary mode.
5518 noclipboard enable -noclipboard mode.
5520 clipboard disable -noclipboard mode.
5522 nosetclipboard enable -nosetclipboard mode.
5524 setclipboard disable -nosetclipboard mode.
5526 seldir:str set -seldir to "str"
5528 resend_cutbuffer resend the most recent CUTBUFFER0 copy
5530 resend_clipboard resend the most recent CLIPBOARD copy
5532 resend_primary resend the most recent PRIMARY copy
5534 cursor:mode enable -cursor "mode".
5536 show_cursor enable showing a cursor.
5538 noshow_cursor disable showing a cursor. (same as "nocursor")
5540 cursor_drag enable cursor changes during drag.
5542 nocursor_drag disable cursor changes during drag.
5544 arrow:n set -arrow to alternate n.
5546 xfixes enable xfixes cursor shape mode.
5548 noxfixes disable xfixes cursor shape mode.
5550 alphacut:n set -alphacut to n.
5552 alphafrac:f set -alphafrac to f.
5554 alpharemove enable -alpharemove mode.
5556 noalpharemove disable -alpharemove mode.
5558 alphablend disable -noalphablend mode.
5560 noalphablend enable -noalphablend mode.
5562 cursorshape disable -nocursorshape mode.
5564 nocursorshape enable -nocursorshape mode.
5566 cursorpos disable -nocursorpos mode.
5568 nocursorpos enable -nocursorpos mode.
5570 xwarp enable -xwarppointer mode.
5572 noxwarp disable -xwarppointer mode.
5574 always_inject enable -always_inject mode.
5576 noalways_inject disable -always_inject mode.
5578 buttonmap:str set -buttonmap "str", empty to disable
5580 dragging disable -nodragging mode.
5582 nodragging enable -nodragging mode.
5584 ncache reenable -ncache mode.
5586 noncache disable -ncache mode.
5588 ncache_size:n set -ncache size to n.
5590 ncache_cr enable -ncache_cr mode.
5592 noncache_cr disable -ncache_cr mode.
5594 ncache_no_moveraise enable no_moveraise mode.
5596 noncache_no_moveraise disable no_moveraise mode.
5598 ncache_no_dtchange enable ncache_no_dtchange mode.
5600 noncache_no_dtchange disable ncache_no_dtchange mode.
5602 ncache_old_wm enable ncache_old_wm mode.
5604 noncache_old_wm disable ncache_old_wm mode.
5606 ncache_no_rootpixmap enable ncache_no_rootpixmap.
5608 noncache_no_rootpixmap disable ncache_no_rootpixmap.
5610 ncache_reset_rootpixmap recheck the root pixmap, ncrp
5612 ncache_keep_anims enable ncache_keep_anims.
5614 noncache_keep_anims disable ncache_keep_anims.
5616 ncache_pad:n set -ncache_pad to n.
5618 wireframe enable -wireframe mode. same as "wf"
5620 nowireframe disable -wireframe mode. same as "nowf"
5622 wireframe:str enable -wireframe mode string.
5624 wireframe_mode:str enable -wireframe mode string.
5626 wireframelocal enable wireframelocal. same as "wfl"
5628 nowireframe disable wireframelocal. same as "nowfl"
5630 wirecopyrect:str set -wirecopyrect string. same as "wcr:"
5632 scrollcopyrect:str set -scrollcopyrect string. same "scr"
5634 noscrollcopyrect disable -scrollcopyrect__mode_. "noscr"
5636 scr_area:n set -scr_area to n
5638 scr_skip:list set -scr_skip to "list"
5640 scr_inc:list set -scr_inc to "list"
5642 scr_keys:list set -scr_keys to "list"
5644 scr_term:list set -scr_term to "list"
5646 scr_keyrepeat:str set -scr_keyrepeat to "str"
5648 scr_parms:str set -scr_parms parameters.
5650 fixscreen:str set -fixscreen to "str".
5652 noxrecord disable all use of RECORD extension.
5654 xrecord enable use of RECORD extension.
5656 reset_record reset RECORD extension (if avail.)
5658 pointer_mode:n set -pointer_mode to n. same as "pm"
5660 input_skip:n set -input_skip to n.
5662 allinput enable use of -allinput mode.
5664 noallinput disable use of -allinput mode.
5666 input_eagerly enable use of -input_eagerly mode.
5668 noinput_eagerly disable use of -input_eagerly mode.
5670 ssltimeout:n set -ssltimeout to n.
5672 speeds:str set -speeds to str.
5674 wmdt:str set -wmdt to str.
5676 debug_pointer enable -debug_pointer, same as "dp"
5678 nodebug_pointer disable -debug_pointer, same as "nodp"
5680 debug_keyboard enable -debug_keyboard, same as "dk"
5682 nodebug_keyboard disable -debug_keyboard, same as "nodk"
5684 keycode:n inject keystroke 'keycode' (xmodmap -pk)
5686 keycode:n,down inject 'keycode' (down=0,1)
5688 keysym:str inject keystroke 'keysym' (number/name)
5690 keysym:str,down inject 'keysym' (down=0,1)
5692 ptr:x,y,mask inject pointer event x, y, button-mask
5694 fakebuttonevent:button,down direct XTestFakeButtonEvent.
5696 sleep:t sleep floating point time t.
5698 get_xprop:p get X property named 'p'.
5700 set_xprop:p:val set X property named 'p' to 'val'. p ->
5702 id=NNN:p for hex/dec window id.
5703 wininfo:id get info about X window id. use 'root' for root
5705 window, use +id for children.
5706 grab_state get state of pointer and keyboard grab.
5708 pointer_pos print XQueryPointer x,y cursor position.
5710 pointer_x print XQueryPointer x cursor position.
5712 pointer_y print XQueryPointer y cursor position.
5714 pointer_same print XQueryPointer ptr on same screen.
5716 pointer_root print XQueryPointer curr ptr rootwin.
5718 pointer_mask print XQueryPointer button and mods mask
5720 mouse_x print x11vnc's idea of cursor position.
5722 mouse_y print x11vnc's idea of cursor position.
5724 noop do nothing.
5726 defer:n set -defer to n ms,same as deferupdate:n
5728 wait:n set -wait to n ms.
5730 extra_fbur:n set -extra_fbur to n.
5732 wait_ui:f set -wait_ui factor to f.
5734 setdefer:n set -setdefer to -2,-1,0,1, or 2.
5736 wait_bog disable -nowait_bog mode.
5738 nowait_bog enable -nowait_bog mode.
5740 slow_fb:f set -slow_fb to f seconds.
5742 xrefresh:f set -xrefresh to f seconds.
5744 readtimeout:n set read timeout to n seconds.
5746 nap enable -nap mode.
5748 nonap disable -nap mode.
5750 sb:n set -sb to n s, same as screen_blank:n
5752 fbpm disable -nofbpm mode.
5754 nofbpm enable -nofbpm mode.
5756 dpms disable -nodpms mode.
5758 nodpms enable -nodpms mode.
5760 forcedpms enable -forcedpms mode.
5762 noforcedpms disable -forcedpms mode.
5764 clientdpms enable -clientdpms mode.
5766 noclientdpms disable -clientdpms mode.
5768 noserverdpms enable -noserverdpms mode.
5770 serverdpms disable -noserverdpms mode.
5772 noultraext enable -noultraext mode.
5774 ultraext disable -noultraext mode.
5776 chatwindow enable local chatwindow mode.
5778 nochatwindow disable local chatwindow mode.
5780 chaton begin chat using local window.
5782 chatoff end chat using local window.
5784 xdamage enable xdamage polling hints.
5786 noxdamage disable xdamage polling hints.
5788 xd_area:A set -xd_area max pixel area to "A"
5790 xd_mem:f set -xd_mem remembrance to "f"
5792 fs:frac set -fs fraction to "frac", e.g. 0.5
5794 gaps:n set -gaps to n.
5796 grow:n set -grow to n.
5798 fuzz:n set -fuzz to n.
5800 snapfb enable -snapfb mode.
5802 nosnapfb disable -snapfb mode.
5804 rawfb:str set -rawfb mode to "str".
5806 uinput_accel:f set uinput_accel to f.
5808 uinput_thresh:n set uinput_thresh to n.
5810 uinput_reset:n set uinput_reset to n ms.
5812 uinput_always:n set uinput_always to 1/0.
5814 progressive:n set LibVNCServer -progressive slice height
5816 parameter to n.
5817 desktop:str set -desktop name to str for new clients.
5819 rfbport:n set -rfbport to n.
5821 macnosaver enable -macnosaver mode.
5823 macsaver disable -macnosaver mode.
5825 macnowait enable -macnowait mode.
5827 macwait disable -macnowait mode.
5829 macwheel:n set -macwheel to n.
5831 macnoswap enable -macnoswap mouse button mode.
5833 macswap disable -macnoswap mouse button mode.
5835 macnoresize enable -macnoresize mode.
5837 macresize disable -macnoresize mode.
5839 maciconanim:n set -maciconanim to n.
5841 macmenu enable -macmenu mode.
5843 macnomenu disable -macmenu mode.
5845 macuskbd enable -macuskbd mode.
5847 macnouskbd disable -macuskbd mode.
5849 httpport:n set -httpport to n.
5851 httpdir:dir set -httpdir to dir (and enable http).
5853 enablehttpproxy enable -enablehttpproxy mode.
5855 noenablehttpproxy disable -enablehttpproxy mode.
5857 alwaysshared enable -alwaysshared mode.
5859 noalwaysshared disable -alwaysshared mode. (may interfere
5861 with other options)
5862 nevershared enable -nevershared mode.
5864 nonevershared disable -nevershared mode. (may interfere with
5866 other options)
5867 dontdisconnect enable -dontdisconnect mode.
5869 nodontdisconnect disable -dontdisconnect mode. (may interfere
5871 with other options)
5872 debug_xevents enable debugging X events.
5874 nodebug_xevents disable debugging X events.
5876 debug_xdamage enable debugging X DAMAGE mechanism.
5878 nodebug_xdamage disable debugging X DAMAGE mechanism.
5880 debug_wireframe enable debugging wireframe mechanism.
5882 nodebug_wireframe disable debugging wireframe mechanism.
5884 debug_scroll enable debugging scrollcopy mechanism.
5886 nodebug_scroll disable debugging scrollcopy mechanism.
5888 debug_tiles enable -debug_tiles
5890 nodebug_tiles disable -debug_tiles
5892 debug_grabs enable -debug_grabs
5894 nodebug_grabs disable -debug_grabs
5896 debug_sel enable -debug_sel
5898 nodebug_sel disable -debug_sel
5900 debug_ncache enable -debug_ncache
5902 nodebug_ncache disable -debug_ncache
5904 dbg enable -dbg crash shell
5906 nodbg disable -dbg crash shell
5908 noremote disable the -remote command processing, it can‐
5910 not be turned back on.
5911 bcx_xattach:str This remote control command is for use with the
5913 BARCO xattach program or the x2x program. Both of these pro‐
5914 grams are for 'pointer and keyboard' sharing between separate X
5915 displays. In general the two displays are usually nearby, e.g.
5916 on the same desk, and this allows the user to share a single
5917 pointer and keyboard between them. The user moves the mouse to
5918 an edge and then the mouse pointer appears to 'jump' to the
5919 other display screen. Thus it emulates what a single X server
5920 would do for two screens (e.g. :0.0 and :0.1) The illusion of a
5921 single Xserver with multiple screens is achieved by forwarding
5922 events to the 2nd one via the XTEST extension.
5923 What the x11vnc bcx_xattach command does is to perform some
5925 pointer movements to try to INDUCE xattach/x2x to 'jump' to the
5926 other display. In what follows the ´master' display refers to
5927 the one that when it has ´focus' it is basically doing nothing
5928 besides watching for the mouse to go over an edge. The 'slave'
5929 display refers to the one to which the mouse and keyboard is
5930 redirected to once an edge in the master has been crossed. Note
5931 that the x11vnc executing the bcx_xattach command MUST be the
5932 one connected to the *master* display.
5933 Also note that when input is being redirected (via XTEST) from
5935 the master display to the slave display, the master display's
5936 pointer and keyboard are *grabbed* by xattach/x2x. x11vnc can
5937 use this info to verify that the master/slave mode change has
5938 taken place correctly. If you specify the "ifneeded" option
5939 (see below) and the initial grab state is that of the desired
5940 final state, then no pointer movements are injected and
5941 "DONE,GRAB_OK" is returned.
5942 "str" must contain one of "up", "down", "left", or "right" to
5944 indicate the direction of the 'jump'. "str" must also contain
5945 one of "master_to_slave" or "slave_to_master" to indicate the
5946 type of mode change induced by the jump. Use "M2S" and "S2M" as
5947 shorter aliases.
5948 "str" may be a "+" separated list of additional tuning options.
5950 The "shift=n" option indicates an offset shift position away
5951 from (0,0) (default 20). "final=x+y" specifies the final posi‐
5952 tion of the cursor at the end of the normal move sequence;
5953 default 30+30. "extra_move=x+y" means to do one more pointer
5954 move after "final" to x+y. "dt=n" sets the sleep time in mil‐
5955 liseconds between pointer moves (default: 40ms) "retry=n" speci‐
5956 fies the maximum number of retries if the grab state change
5957 fails. "ifneeded" means to not apply the pointer movements if
5958 the initial grab state is that of the desired final state.
5959 "nograbcheck" means to not check if the grab state changed as
5960 expected and only apply the pointer movements (default is to
5961 check the grab states.)
5962 If you do not specify "up", etc., to bcx_xattach nothing will be
5964 attempted and the command returns the string FAIL,NO_DIREC‐
5965 TION_SPECIFIED. If you do not specify "master_to_slave" or
5966 "M2S", etc., to bcx_xattach nothing will be attempted and the
5967 command returns the string FAIL,NO_MODE_CHANGE_SPECIFIED.
5968 Otherwise, the returned string will contain "DONE". It will be
5970 "DONE,GRAB_OK" if the grab state changed as expected (or if
5971 "ifneeded" was supplied and the initial grab state was already
5972 the desired one.) If the initial grab state was incorrect, but
5973 the final grab state was correct then it is
5974 "DONE,GRAB_FAIL_INIT". If the initial grab state was correct,
5975 but the final grab state was incorrect then it is
5976 "DONE,GRAB_FAIL_FINAL". If both are incorrect it will be
5977 "DONE,GRAB_FAIL". Under grab failure the string will be fol‐
5978 lowed by ":p1,k1-p2,k2" where p1,k1 indicates the initial
5979 pointer and keyboard grab states and p2,k2 the final ones. If
5980 GRAB_FAIL or GRAB_FAIL_FINAL occurs, the action will be retried
5981 up to 3 times; trying to reset the state and sleeping a bit
5982 between each try. Set retry=n to adjust the number of retries,
5983 zero to disable retries.
5984 Examples: -R bcx_xattach:down+M2S -R bcx_xattach:up+S2M -R
5986 bcx_xattach:up+S2M+nograbcheck+dt=30 -R bcx_xat‐
5987 tach:down+M2S+extra_move=100+100
5988 or use -Q instead of -R to retrieve the result text.
5990 End of the bcx_xattach:str description.
5992 The vncconnect(1) command from standard VNC distributions may
5994 also be used if string is prefixed with "cmd=" E.g. 'vncconnect
5995 cmd=stop'. Under some circumstances xprop(1) can used if it
5996 supports -set (see the FAQ).
5997 If "-connect /path/to/file" has been supplied to the running
5999 x11vnc server then that file can be used as a communication
6000 channel (this is the only way to remote control one of many
6001 x11vnc's polling the same X display) Simply run: 'x11vnc -con‐
6002 nect /path/to/file -remote ...' or you can directly write to
6003 the file via something like: "echo cmd=stop > /path/to/file",
6004 etc.
6005 -query variable
6007 Like -remote, except just query the value of variable. "-Q" is
6009 an alias for "-query". Multiple queries can be done by separat‐
6010 ing variables by commas, e.g. -query var1,var2. The results come
6011 back in the form ans=var1:value1,ans=var2:value2,... to the
6012 standard output. If a variable is read-only, it comes back with
6013 prefix "aro=" instead of "ans=".
6014 Some -remote commands are pure actions that do not make sense as
6016 variables, e.g. "stop" or "disconnect", in these cases the value
6017 returned is "N/A". To direct a query straight to the
6018 X11VNC_REMOTE property or connect file use "qry=..." instead of
6019 "cmd=..."
6020 ans= stop quit exit shutdown ping resend_cutbuffer resend_clip‐
6022 board resend_primary blacken zero refresh reset close disconnect
6023 id_cmd id sid waitmapped nowaitmapped clip flashcmap noflashcmap
6024 shiftcmap truecolor notruecolor overlay nooverlay overlay_cursor
6025 overlay_yescursor nooverlay_nocursor nooverlay_cursor noover‐
6026 lay_yescursor overlay_nocursor 8to24 no8to24 8to24_opts 24to32
6027 no24to32 visual scale scale_cursor viewonly noviewonly shared
6028 noshared forever noforever once timeout tightfilexfer notight‐
6029 filexfer ultrafilexfer noultrafilexfer rfbversion deny lock
6030 nodeny unlock avahi mdns zeroconf noavahi nomdns nozeroconf con‐
6031 nect proxy allowonce allow noipv6 ipv6 noipv4 ipv4 no6 6 local‐
6032 host nolocalhost listen lookup nolookup accept afteraccept gone
6033 shm noshm flipbyteorder noflipbyteorder onetile noonetile
6034 solid_color solid nosolid blackout xinerama noxinerama xtrap
6035 noxtrap xrandr noxrandr xrandr_mode rotate padgeom quiet q
6036 noquiet modtweak nomodtweak xkb noxkb capslock nocapslock
6037 skip_lockkeys noskip_lockkeys skip_keycodes sloppy_keys
6038 nosloppy_keys skip_dups noskip_dups add_keysyms noadd_keysyms
6039 clear_mods noclear_mods clear_keys noclear_keys clear_all
6040 clear_locks keystate remap repeat norepeat fb nofb bell nobell
6041 sendbell sel nosel primary noprimary setprimary nosetprimary
6042 clipboard noclipboard setclipboard nosetclipboard seldir cursor‐
6043 shape nocursorshape cursorpos nocursorpos cursor_drag nocur‐
6044 sor_drag cursor show_cursor noshow_cursor nocursor arrow xfixes
6045 noxfixes xdamage noxdamage xd_area xd_mem alphacut alphafrac
6046 alpharemove noalpharemove alphablend noalphablend xwarppointer
6047 xwarp noxwarppointer noxwarp always_inject noalways_inject but‐
6048 tonmap dragging nodragging ncache_cr noncache_cr
6049 ncache_no_moveraise noncache_no_moveraise ncache_no_dtchange
6050 noncache_no_dtchange ncache_no_rootpixmap noncache_no_rootpixmap
6051 ncache_reset_rootpixmap ncrp ncache_keep_anims non‐
6052 cache_keep_anims ncache_old_wm noncache_old_wm ncache_pad ncache
6053 noncache ncache_size debug_ncache nodebug_ncache wireframe_mode
6054 wireframe wf nowireframe nowf wireframelocal wfl nowireframelo‐
6055 cal nowfl wirecopyrect wcr nowirecopyrect nowcr scr_area
6056 scr_skip scr_inc scr_keys scr_term scr_keyrepeat scr_parms
6057 scrollcopyrect scr noscrollcopyrect noscr fixscreen noxrecord
6058 xrecord reset_record pointer_mode pm input_skip allinput
6059 noallinput input_eagerly noinput_eagerly input grabkbd nograbkbd
6060 grabptr nograbptr grabalways nograbalways grablocal client_input
6061 ssltimeout speeds wmdt debug_pointer dp nodebug_pointer nodp
6062 debug_keyboard dk nodebug_keyboard nodk keycode keysym ptr fake‐
6063 buttonevent sleep get_xprop set_xprop wininfo bcx_xattach defer‐
6064 update defer setdefer extra_fbur wait_ui wait_bog nowait_bog
6065 slow_fb xrefresh wait readtimeout nap nonap sb screen_blank fbpm
6066 nofbpm dpms nodpms clientdpms noclientdpms forcedpms noforcedpms
6067 noserverdpms serverdpms noultraext ultraext chatwindow
6068 nochatwindow chaton chatoff fs gaps grow fuzz snapfb nosnapfb
6069 rawfb uinput_accel uinput_thresh uinput_reset uinput_always pro‐
6070 gressive rfbport http nohttp httpport httpdir enablehttpproxy
6071 noenablehttpproxy alwaysshared noalwaysshared nevershared noal‐
6072 waysshared dontdisconnect nodontdisconnect desktop debug_xevents
6073 nodebug_xevents debug_xevents debug_xdamage nodebug_xdamage
6074 debug_xdamage debug_wireframe nodebug_wireframe debug_wireframe
6075 debug_scroll nodebug_scroll debug_scroll debug_tiles dbt node‐
6076 bug_tiles nodbt debug_tiles debug_grabs nodebug_grabs debug_sel
6077 nodebug_sel dbg nodbg macnosaver macsaver nomacnosaver macnowait
6078 macwait nomacnowait macwheel macnoswap macswap nomacnoswap mac‐
6079 noresize macresize nomacnoresize maciconanim macmenu macnomenu
6080 nomacmenu macuskbd nomacuskbd noremote
6081 aro= noop display vncdisplay icon_mode autoport loop loopbg
6083 desktopname guess_desktop guess_dbus http_url auth xauth users
6084 rootshift clipshift scale_str scaled_x scaled_y scale_numer
6085 scale_denom scale_fac_x scale_fac_y scaling_blend scal‐
6086 ing_nomult4 scaling_pad scaling_interpolate inetd privremote
6087 unsafe safer nocmds passwdfile unixpw unixpw_nis unixpw_list ssl
6088 ssl_pem sslverify stunnel stunnel_pem https httpsredir usepw
6089 using_shm logfile o flag rmflag rc norc h help V version lastmod
6090 bg sigpipe threads readrate netrate netlatency pipeinput clients
6091 client_count pid ext_xtest ext_xtrap ext_xrecord ext_xkb
6092 ext_xshm ext_xinerama ext_overlay ext_xfixes ext_xdamage
6093 ext_xrandr rootwin num_buttons button_mask mouse_x mouse_y
6094 grab_state pointer_pos pointer_x pointer_y pointer_same
6095 pointer_root pointer_mask bpp depth indexed_color dpy_x dpy_y
6096 wdpy_x wdpy_y off_x off_y cdpy_x cdpy_y coff_x coff_y rfbauth
6097 passwd viewpasswd
6098 -QD variable
6100 Just like -query variable, but returns the default value for
6102 that parameter (no running x11vnc server is consulted)
6103 -sync
6105 By default -remote commands are run asynchronously, that is, the
6107 request is posted and the program immediately exits. Use -sync
6108 to have the program wait for an acknowledgement from the x11vnc
6109 server that command was processed (somehow). On the other hand
6110 -query requests are always processed synchronously because they
6111 have to wait for the answer.
6112 Also note that if both -remote and -query requests are supplied
6114 on the command line, the -remote is processed first (syn‐
6115 chronously: no need for -sync), and then the -query request is
6116 processed in the normal way. This allows for a reliable way to
6117 see if the -remote command was processed by querying for any new
6118 settings. Note however that there is timeout of a few seconds
6119 (see the next paragraph) so if the x11vnc takes longer than that
6120 to process the requests the requester will think that a failure
6121 has taken place.
6122 The default is to wait 3.5 seconds. Or if cmd=stop only 1.0
6124 seconds. If cmd matches 'script:' then it will wait up to 10.0
6125 seconds. Set X11VNC_SYNC_TIMEOUT to the number of seconds you
6126 want it to wait.
6127 -query_retries str
6129 If a query fails to get a response from an x11vnc server, retry
6131 up to n times. str is specified as n[:t][/match] Optionally
6132 the delay between tries may be specified by "t" a floating point
6133 time (default 0.5 seconds.) Note: the response is not checked
6134 for validity or whether it corresponds to the query sent. The
6135 query "ping:mystring" may be used to help uniquely identify the
6136 query. Optionally, a matching string after a "/" will be used
6137 to check the result text. Up to n retries will take place until
6138 the matching string is found in the output text. If the match
6139 string is never found the program's exit code is 1; if the match
6140 is found it exits with 0. Note that there may be stdout printed
6141 for each retry (i.e. multiple lines printed out to stdout.)
6142 Example: -query_retries 4:1.5/grab_state
6143 -remote_prefix str
6145 Enable a remote-control communication channel for connected VNC
6147 clients. str is a non-empty string. If a VNC client sends rfb‐
6148 CutText having the prefix str then the part after it is pro‐
6149 cessed as though it were sent via 'x11vnc -remote ...'. If it
6150 begins with neither 'cmd=' nor 'qry=' then 'qry=' is assumed.
6151 Any corresponding output text for that remote control command is
6152 sent back to all client as rfbCutText. The returned output is
6153 also prefixed with str. Example: -remote_prefix DO_THIS:
6154 Note that enabling -remote_prefix allows the remote VNC viewers
6156 to run x11vnc -remote commands. Do not use this option if they
6157 are not to be trusted.
6158 -noremote, -yesremote
6160 Do not process any remote control commands or queries. Do
6162 process remote control commands or queries. Default: -yesremote
6163 A note about security wrt remote control commands. If someone
6165 can connect to the X display and change the property
6166 X11VNC_REMOTE, then they can remotely control x11vnc. Normally
6167 access to the X display is protected. Note that if they can
6168 modify X11VNC_REMOTE on the X server, they have enough permis‐
6169 sions to also run their own x11vnc and thus have complete con‐
6170 trol of the desktop. If the "-connect /path/to/file" channel
6171 is being used, obviously anyone who can write to /path/to/file
6172 can remotely control x11vnc. So be sure to protect the X dis‐
6173 play and that file's write permissions. See -privremote below.
6174 If you are paranoid and do not think -noremote is enough, to
6176 disable the X11VNC_REMOTE property channel completely use
6177 -novncconnect, or use the -safer option that shuts many things
6178 off.
6179 -unsafe
6181 A few remote commands are disabled by default (currently:
6183 id:pick, accept:<cmd>, gone:<cmd>, and rawfb:setup:<cmd>)
6184 because they are associated with running external programs. If
6185 you specify -unsafe, then these remote-control commands are
6186 allowed. Note that you can still specify these parameters on
6187 the command line, they just cannot be invoked via remote-con‐
6188 trol.
6189 -safer
6191 Equivalent to: -novncconnect -noremote and prohibiting -gui and
6193 the -connect file. Shuts off communcation channels.
6194 -privremote
6196 Perform some sanity checks and disable remote-control commands
6198 if it appears that the X DISPLAY and/or connectfile can be
6199 accessed by other users. Once remote-control is disabled it
6200 cannot be turned back on.
6201 -nocmds
6203 No external commands (e.g. system(3) , popen(3) , exec(3) )
6205 will be run at all.
6206 -allowedcmds list
6208 list contains a comma separated list of the only external com‐
6210 mands that can be run. The full list of associated options is:
6211 stunnel, ssl, unixpw, WAIT, zeroconf, id, accept, afteraccept,
6213 gone, pipeinput, v4l-info, rawfb-setup, dt, gui, ssh,
6214 storepasswd, passwdfile, custom_passwd, findauth, crash.
6215 See each option's help to learn the associated external command.
6217 Note that the -nocmds option takes precedence and disables all
6218 external commands.
6219 -deny_all
6221 For use with -remote nodeny: start out denying all incoming
6223 clients until "-remote nodeny" is used to let them in.
6224 These options are passed to LibVNCServer:
6226 -rfbport port
6228 TCP port for RFB protocol
6230 -rfbwait time
6232 max time in ms to wait for RFB client
6234 -rfbauth passwd-file
6236 use authentication on RFB protocol (use 'x11vnc -storepasswd
6238 pass file' to create a password file)
6239 -rfbversion 3.x
6241 Set the version of the RFB we choose to advertise
6243 -permitfiletransfer
6245 permit file transfer support
6247 -passwd plain-password
6249 use authentication (use plain-password as password, USE AT YOUR
6251 RISK)
6252 -deferupdate time
6254 time in ms to defer updates (default 40)
6256 -deferptrupdate time
6258 time in ms to defer pointer updates (default none)
6260 -desktop name
6262 VNC desktop name (default "LibVNCServer")
6264 -alwaysshared
6266 always treat new clients as shared
6268 -nevershared
6270 never treat new clients as shared
6272 -dontdisconnect
6274 don't disconnect existing clients when a new non-shared connec‐
6276 tion comes in (refuse new connection instead)
6277 -httpdir dir-path
6279 enable http server using dir-path home
6281 -httpport portnum
6283 use portnum for http connection
6285 -enablehttpproxy
6287 enable http proxy support
6289 -progressive height
6291 enable progressive updating for slow links
6293 -listen ipaddr
6295 listen for connections only on network interface with addr
6297 ipaddr. '-listen localhost' and hostname work too.
6298 libvncserver-tight-extension options:
6300 -disablefiletransfer
6302 disable file transfer
6304 -ftproot string
6306 set ftp root
6308
6310 $HOME/.x11vncrc, $HOME/.Xauthority
6311
6313 DISPLAY, XAUTHORITY, HOME
6314 The following are set for the auxiliary commands run by -accept, -gone
6316 and other cases:
6317 RFB_CLIENT_IP, RFB_CLIENT_PORT, RFB_SERVER_IP, RFB_SERVER_PORT,
6319 RFB_X11VNC_PID, RFB_CLIENT_ID, RFB_CLIENT_COUNT, RFB_MODE RFB_STATE
6320 RFB_LOGIN_VIEWONLY RFB_LOGIN_TIME RFB_CURRENT_TIME RFB_USERNAME
6321 RFB_SSL_CLIENT_CERT
6322
6324 vncviewer(1), vncpasswd(1), vncconnect(1), vncserver(1), Xvnc(1),
6325 xev(1), xdpyinfo(1), xwininfo(1), xprop(1), xmodmap(1), xrandr(1),
6326 Xserver(1), xauth(1), xhost(1), Xsecurity(7), xmessage(1), XGetIm‐
6327 age(3X11), ipcrm(1), inetd(1), xdm(1), gdm(1), kdm(1), ssh(1), stun‐
6328 nel(8), su(1), http://www.tightvnc.com, http://www.realvnc.com,
6329 http://www.karlrunge.com/x11vnc/, http://www.karlrunge.com/x11vnc/#faq
6330
6332 x11vnc was written by Karl J. Runge <runge@karlrunge.com>, it is part
6333 of the LibVNCServer project <http://sf.net/projects/libvncserver>.
6334 This manual page is based one the one written by Ludovic Drolez
6335 <ldrolez@debian.org>, for the Debian project (both may be used by oth‐
6336 ers).
6337x11vnc April 2014 X11VNC(1)