1PPPD(8) System Manager's Manual PPPD(8)
2
6 pppd - Point-to-Point Protocol Daemon
7
9 pppd [ options ]
10
12 PPP is the protocol used for establishing internet links over dial-up
13 modems, DSL connections, and many other types of point-to-point links.
14 The pppd daemon works together with the kernel PPP driver to establish
15 and maintain a PPP link with another system (called the peer) and to
16 negotiate Internet Protocol (IP) addresses for each end of the link.
17 Pppd can also authenticate the peer and/or supply authentication infor‐
18 mation to the peer. PPP can be used with other network protocols be‐
19 sides IP, but such use is becoming increasingly rare.
20
22 ttyname
23 Use the serial port called ttyname to communicate with the peer.
24 If ttyname does not begin with a slash (/), the string "/dev/"
25 is prepended to ttyname to form the name of the device to open.
26 If no device name is given, or if the name of the terminal con‐
27 nected to the standard input is given, pppd will use that termi‐
28 nal, and will not fork to put itself in the background. A value
29 for this option from a privileged source cannot be overridden by
30 a non-privileged user.
31 speed An option that is a decimal number is taken as the desired baud
33 rate for the serial device. On systems such as 4.4BSD and Net‐
34 BSD, any speed can be specified. Other systems (e.g. Linux,
35 SunOS) only support the commonly-used baud rates.
36 asyncmap map
38 This option sets the Async-Control-Character-Map (ACCM) for this
39 end of the link. The ACCM is a set of 32 bits, one for each of
40 the ASCII control characters with values from 0 to 31, where a 1
41 bit indicates that the corresponding control character should
42 not be used in PPP packets sent to this system. The map is en‐
43 coded as a hexadecimal number (without a leading 0x) where the
44 least significant bit (00000001) represents character 0 and the
45 most significant bit (80000000) represents character 31. Pppd
46 will ask the peer to send these characters as a 2-byte escape
47 sequence. If multiple asyncmap options are given, the values
48 are ORed together. If no asyncmap option is given, the default
49 is zero, so pppd will ask the peer not to escape any control
50 characters. To escape transmitted characters, use the escape
51 option.
52 auth Require the peer to authenticate itself before allowing network
54 packets to be sent or received. This option is the default if
55 the system has a default route. If neither this option nor the
56 noauth option is specified, pppd will only allow the peer to use
57 IP addresses to which the system does not already have a route.
58 call name
60 Read additional options from the file /etc/ppp/peers/name. This
61 file may contain privileged options, such as noauth, even if
62 pppd is not being run by root. The name string may not begin
63 with / or include .. as a pathname component. The format of the
64 options file is described below.
65 connect script
67 Usually there is something which needs to be done to prepare the
68 link before the PPP protocol can be started; for instance, with
69 a dial-up modem, commands need to be sent to the modem to dial
70 the appropriate phone number. This option specifies an command
71 for pppd to execute (by passing it to a shell) before attempting
72 to start PPP negotiation. The chat (8) program is often useful
73 here, as it provides a way to send arbitrary strings to a modem
74 and respond to received characters. A value for this option
75 from a privileged source cannot be overridden by a non-privi‐
76 leged user.
77 crtscts
79 Specifies that pppd should set the serial port to use hardware
80 flow control using the RTS and CTS signals in the RS-232 inter‐
81 face. If neither the crtscts, the nocrtscts, the cdtrcts nor
82 the nocdtrcts option is given, the hardware flow control setting
83 for the serial port is left unchanged. Some serial ports (such
84 as Macintosh serial ports) lack a true RTS output. Such serial
85 ports use this mode to implement unidirectional flow control.
86 The serial port will suspend transmission when requested by the
87 modem (via CTS) but will be unable to request the modem to stop
88 sending to the computer. This mode retains the ability to use
89 DTR as a modem control line.
90 defaultroute
92 Add a default route to the system routing tables, using the peer
93 as the gateway, when IPCP negotiation is successfully completed.
94 This entry is removed when the PPP connection is broken. This
95 option is privileged if the nodefaultroute option has been spec‐
96 ified.
97 defaultroute-metric
99 Define the metric of the defaultroute and only add it if there
100 is no other default route with the same metric. With the de‐
101 fault value of -1, the route is only added if there is no de‐
102 fault route at all.
103 defaultroute6
105 Add a default IPv6 route to the system routing tables, using the
106 peer as the gateway, when IPv6CP negotiation is successfully
107 completed. This entry is removed when the PPP connection is
108 broken. This option is privileged if the nodefaultroute6 option
109 has been specified.
110 replacedefaultroute
112 This option is a flag to the defaultroute option. If default‐
113 route is set and this flag is also set, pppd replaces an exist‐
114 ing default route with the new default route. This option is
115 privileged.
116 disconnect script
118 Execute the command specified by script, by passing it to a
119 shell, after pppd has terminated the link. This command could,
120 for example, issue commands to the modem to cause it to hang up
121 if hardware modem control signals were not available. The dis‐
122 connect script is not run if the modem has already hung up. A
123 value for this option from a privileged source cannot be over‐
124 ridden by a non-privileged user.
125 escape xx,yy,...
127 Specifies that certain characters should be escaped on transmis‐
128 sion (regardless of whether the peer requests them to be escaped
129 with its async control character map). The characters to be es‐
130 caped are specified as a list of hex numbers separated by com‐
131 mas. Note that almost any character can be specified for the
132 escape option, unlike the asyncmap option which only allows con‐
133 trol characters to be specified. The characters which may not
134 be escaped are those with hex values 0x20 - 0x3f or 0x5e.
135 file name
137 Read options from file name (the format is described below).
138 The file must be readable by the user who has invoked pppd.
139 init script
141 Execute the command specified by script, by passing it to a
142 shell, to initialize the serial line. This script would typi‐
143 cally use the chat(8) program to configure the modem to enable
144 auto answer. A value for this option from a privileged source
145 cannot be overridden by a non-privileged user.
146 lock Specifies that pppd should create a UUCP-style lock file for the
148 serial device to ensure exclusive access to the device. By de‐
149 fault, pppd will not create a lock file.
150 mru n Set the MRU [Maximum Receive Unit] value to n. Pppd will ask the
152 peer to send packets of no more than n bytes. The value of n
153 must be between 128 and 16384; the default is 1500. A value of
154 296 works well on very slow links (40 bytes for TCP/IP header +
155 256 bytes of data). Note that for the IPv6 protocol, the MRU
156 must be at least 1280.
157 mtu n Set the MTU [Maximum Transmit Unit] value to n. Unless the peer
159 requests a smaller value via MRU negotiation, pppd will request
160 that the kernel networking code send data packets of no more
161 than n bytes through the PPP network interface. Note that for
162 the IPv6 protocol, the MTU must be at least 1280.
163 passive
165 Enables the "passive" option in the LCP. With this option, pppd
166 will attempt to initiate a connection; if no reply is received
167 from the peer, pppd will then just wait passively for a valid
168 LCP packet from the peer, instead of exiting, as it would with‐
169 out this option.
170
172 <local_IP_address>:<remote_IP_address>
173 Set the local and/or remote interface IP addresses. Either one
174 may be omitted. The IP addresses can be specified with a host
175 name or in decimal dot notation (e.g. 150.234.56.78). The de‐
176 fault local address is the (first) IP address of the system (un‐
177 less the noipdefault option is given). The remote address will
178 be obtained from the peer if not specified in any option. Thus,
179 in simple cases, this option is not required. If a local and/or
180 remote IP address is specified with this option, pppd will not
181 accept a different value from the peer in the IPCP negotiation,
182 unless the ipcp-accept-local and/or ipcp-accept-remote options
183 are given, respectively.
184 +ipv6 Enable the IPv6CP and IPv6 protocols.
186 ipv6 <local_interface_identifier>,<remote_interface_identifier>
188 Set the local and/or remote 64-bit interface identifier. Either
189 one may be omitted. The identifier must be specified in standard
190 ASCII notation of IPv6 addresses (e.g. ::dead:beef). If the
191 ipv6cp-use-ipaddr option is given, the local identifier is the
192 local IPv4 address (see above). On systems which supports a
193 unique persistent id, such as EUI-48 derived from the Ethernet
194 MAC address, ipv6cp-use-persistent option can be used to replace
195 the ipv6 <local>,<remote> option. Otherwise the identifier is
196 randomized.
197 active-filter filter-expression
199 Specifies a packet filter to be applied to data packets to de‐
200 termine which packets are to be regarded as link activity, and
201 therefore reset the idle timer, or cause the link to be brought
202 up in demand-dialling mode. This option is useful in conjunc‐
203 tion with the idle option if there are packets being sent or re‐
204 ceived regularly over the link (for example, routing information
205 packets) which would otherwise prevent the link from ever ap‐
206 pearing to be idle. The filter-expression syntax is as de‐
207 scribed for tcpdump(1), except that qualifiers which are inap‐
208 propriate for a PPP link, such as ether and arp, are not permit‐
209 ted. Generally the filter expression should be enclosed in sin‐
210 gle-quotes to prevent whitespace in the expression from being
211 interpreted by the shell. This option is currently only avail‐
212 able under Linux, and requires that the kernel was configured to
213 include PPP filtering support (CONFIG_PPP_FILTER). Note that it
214 is possible to apply different constraints to incoming and out‐
215 going packets using the inbound and outbound qualifiers.
216 allow-ip address(es)
218 Allow peers to use the given IP address or subnet without au‐
219 thenticating themselves. The parameter is parsed as for each
220 element of the list of allowed IP addresses in the secrets files
221 (see the AUTHENTICATION section below).
222 allow-number number
224 Allow peers to connect from the given telephone number. A
225 trailing `*' character will match all numbers beginning with the
226 leading part.
227 bsdcomp nr,nt
229 Request that the peer compress packets that it sends, using the
230 BSD-Compress scheme, with a maximum code size of nr bits, and
231 agree to compress packets sent to the peer with a maximum code
232 size of nt bits. If nt is not specified, it defaults to the
233 value given for nr. Values in the range 9 to 15 may be used for
234 nr and nt; larger values give better compression but consume
235 more kernel memory for compression dictionaries. Alternatively,
236 a value of 0 for nr or nt disables compression in the corre‐
237 sponding direction. Use nobsdcomp or bsdcomp 0 to disable BSD-
238 Compress compression entirely.
239 ca ca-file
241 (EAP-TLS) Use the file ca-file as the X.509 Certificate Author‐
242 ity (CA) file (in PEM format), needed for setting up an EAP-TLS
243 connection. This option is used on the client-side in conjunc‐
244 tion with the cert and key options.
245 cdtrcts
247 Use a non-standard hardware flow control (i.e. DTR/CTS) to con‐
248 trol the flow of data on the serial port. If neither the
249 crtscts, the nocrtscts, the cdtrcts nor the nocdtrcts option is
250 given, the hardware flow control setting for the serial port is
251 left unchanged. Some serial ports (such as Macintosh serial
252 ports) lack a true RTS output. Such serial ports use this mode
253 to implement true bi-directional flow control. The sacrifice is
254 that this flow control mode does not permit using DTR as a modem
255 control line.
256 cert certfile
258 (EAP-TLS) Use the file certfile as the X.509 certificate (in PEM
259 format), needed for setting up an EAP-TLS connection. This op‐
260 tion is used on the client-side in conjunction with the ca and
261 key options.
262 chap-interval n
264 If this option is given, pppd will rechallenge the peer every n
265 seconds.
266 chap-max-challenge n
268 Set the maximum number of CHAP challenge transmissions to n (de‐
269 fault 10).
270 chap-restart n
272 Set the CHAP restart interval (retransmission timeout for chal‐
273 lenges) to n seconds (default 3).
274 chap-timeout n
276 Set timeout for CHAP authentication by peer to n seconds (de‐
277 fault 60).
278 chapms-strip-domain
280 Some Windows 9x/ME clients might be transmitting the MS domain
281 before the username in the provided client name. This option en‐
282 ables stripping the domain from the client name on the server
283 side before matching it against the secret file.
284 child-timeout n
286 When exiting, wait for up to n seconds for any child processes
287 (such as the command specified with the pty command) to exit be‐
288 fore exiting. At the end of the timeout, pppd will send a
289 SIGTERM signal to any remaining child processes and exit. A
290 value of 0 means no timeout, that is, pppd will wait until all
291 child processes have exited.
292 connect-delay n
294 Wait for up to n milliseconds after the connect script finishes
295 for a valid PPP packet from the peer. At the end of this time,
296 or when a valid PPP packet is received from the peer, pppd will
297 commence negotiation by sending its first LCP packet. The de‐
298 fault value is 1000 (1 second). This wait period only applies
299 if the connect or pty option is used.
300 crl filename
302 (EAP-TLS) Use the file filename as the Certificate Revocation
303 List to check for the validity of the peer's certificate. This
304 option is not mandatory for setting up an EAP-TLS connection.
305 Also see the crl-dir option.
306 crl-dir directory
308 (EAP-TLS) Use the directory directory to scan for CRL files in
309 has format ($hash.r0) to check for the validity of the peer's
310 certificate. This option is not mandatory for setting up an
311 EAP-TLS connection. Also see the crl option.
312 debug Enables connection debugging facilities. If this option is
314 given, pppd will log the contents of all control packets sent or
315 received in a readable form. The packets are logged through
316 syslog with facility daemon and level debug. This information
317 can be directed to a file by setting up /etc/syslog.conf appro‐
318 priately (see syslog.conf(5)).
319 default-asyncmap
321 Disable asyncmap negotiation, forcing all control characters to
322 be escaped for both the transmit and the receive direction.
323 default-mru
325 Disable MRU [Maximum Receive Unit] negotiation. With this op‐
326 tion, pppd will use the default MRU value of 1500 bytes for both
327 the transmit and receive direction.
328 deflate nr,nt
330 Request that the peer compress packets that it sends, using the
331 Deflate scheme, with a maximum window size of 2**nr bytes, and
332 agree to compress packets sent to the peer with a maximum window
333 size of 2**nt bytes. If nt is not specified, it defaults to the
334 value given for nr. Values in the range 9 to 15 may be used for
335 nr and nt; larger values give better compression but consume
336 more kernel memory for compression dictionaries. Alternatively,
337 a value of 0 for nr or nt disables compression in the corre‐
338 sponding direction. Use nodeflate or deflate 0 to disable De‐
339 flate compression entirely. (Note: pppd requests Deflate com‐
340 pression in preference to BSD-Compress if the peer can do ei‐
341 ther.)
342 demand Initiate the link only on demand, i.e. when data traffic is
344 present. With this option, the remote IP address may be speci‐
345 fied by the user on the command line or in an options file, or
346 if not, pppd will use an arbitrary address in the 10.x.x.x
347 range. Pppd will initially configure the interface and enable
348 it for IP traffic without connecting to the peer. When traffic
349 is available, pppd will connect to the peer and perform negotia‐
350 tion, authentication, etc. When this is completed, pppd will
351 commence passing data packets (i.e., IP packets) across the
352 link.
353 The demand option implies the persist option. If this behaviour
355 is not desired, use the nopersist option after the demand op‐
356 tion. The idle and holdoff options are also useful in conjunc‐
357 tion with the demand option.
358 domain d
360 Append the domain name d to the local host name for authentica‐
361 tion purposes. For example, if gethostname() returns the name
362 porsche, but the fully qualified domain name is
363 porsche.Quotron.COM, you could specify domain Quotron.COM. Pppd
364 would then use the name porsche.Quotron.COM for looking up se‐
365 crets in the secrets file, and as the default name to send to
366 the peer when authenticating itself to the peer. This option is
367 privileged.
368 dryrun With the dryrun option, pppd will print out all the option val‐
370 ues which have been set and then exit, after parsing the command
371 line and options files and checking the option values, but be‐
372 fore initiating the link. The option values are logged at level
373 info, and also printed to standard output unless the device on
374 standard output is the device that pppd would be using to commu‐
375 nicate with the peer.
376 dump With the dump option, pppd will print out all the option values
378 which have been set. This option is like the dryrun option ex‐
379 cept that pppd proceeds as normal rather than exiting.
380 enable-session
382 Enables session accounting via PAM or wtwp/wtmpx, as appropri‐
383 ate. When PAM is enabled, the PAM "account" and "session" mod‐
384 ule stacks determine behavior, and are enabled for all PPP au‐
385 thentication protocols. When PAM is disabled, wtmp/wtmpx en‐
386 tries are recorded regardless of whether the peer name identi‐
387 fies a valid user on the local system, making peers visible in
388 the last(1) log. This feature is automatically enabled when the
389 pppd login option is used. Session accounting is disabled by
390 default.
391 endpoint <epdisc>
393 Sets the endpoint discriminator sent by the local machine to the
394 peer during multilink negotiation to <epdisc>. The default is
395 to use the MAC address of the first ethernet interface on the
396 system, if any, otherwise the IPv4 address corresponding to the
397 hostname, if any, provided it is not in the multicast or lo‐
398 cally-assigned IP address ranges, or the localhost address. The
399 endpoint discriminator can be the string null or of the form
400 type:value, where type is a decimal number or one of the strings
401 local, IP, MAC, magic, or phone. The value is an IP address in
402 dotted-decimal notation for the IP type, or a string of bytes in
403 hexadecimal, separated by periods or colons for the other types.
404 For the MAC type, the value may also be the name of an ethernet
405 or similar network interface. This option is currently only
406 available under Linux.
407 eap-interval n
409 If this option is given and pppd authenticates the peer with EAP
410 (i.e., is the server), pppd will restart EAP authentication ev‐
411 ery n seconds. For EAP SRP-SHA1, see also the srp-interval op‐
412 tion, which enables lightweight rechallenge.
413 eap-max-rreq n
415 Set the maximum number of EAP Requests to which pppd will re‐
416 spond (as a client) without hearing EAP Success or Failure.
417 (Default is 20.)
418 eap-max-sreq n
420 Set the maximum number of EAP Requests that pppd will issue (as
421 a server) while attempting authentication. (Default is 10.)
422 eap-restart n
424 Set the retransmit timeout for EAP Requests when acting as a
425 server (authenticator). (Default is 3 seconds.)
426 eap-timeout n
428 Set the maximum time to wait for the peer to send an EAP Request
429 when acting as a client (authenticatee). (Default is 20 sec‐
430 onds.)
431 hide-password
433 When logging the contents of PAP packets, this option causes
434 pppd to exclude the password string from the log. This is the
435 default.
436 holdoff n
438 Specifies how many seconds to wait before re-initiating the link
439 after it terminates. This option only has any effect if the
440 persist or demand option is used. The holdoff period is not ap‐
441 plied if the link was terminated because it was idle.
442 idle n Specifies that pppd should disconnect if the link is idle for n
444 seconds. The link is idle when no data packets (i.e. IP pack‐
445 ets) are being sent or received. Note: it is not advisable to
446 use this option with the persist option without the demand op‐
447 tion. If the active-filter option is given, data packets which
448 are rejected by the specified activity filter also count as the
449 link being idle.
450 ipcp-accept-local
452 With this option, pppd will accept the peer's idea of our local
453 IP address, even if the local IP address was specified in an op‐
454 tion.
455 ipcp-accept-remote
457 With this option, pppd will accept the peer's idea of its (re‐
458 mote) IP address, even if the remote IP address was specified in
459 an option.
460 ipcp-max-configure n
462 Set the maximum number of IPCP configure-request transmissions
463 to n (default 10).
464 ipcp-max-failure n
466 Set the maximum number of IPCP configure-NAKs returned before
467 starting to send configure-Rejects instead to n (default 10).
468 ipcp-max-terminate n
470 Set the maximum number of IPCP terminate-request transmissions
471 to n (default 3).
472 ipcp-restart n
474 Set the IPCP restart interval (retransmission timeout) to n sec‐
475 onds (default 3).
476 ipparam string
478 Provides an extra parameter to the ip-up, ip-pre-up and ip-down
479 scripts. If this option is given, the string supplied is given
480 as the 6th parameter to those scripts.
481 ipv6cp-accept-local
483 With this option, pppd will accept the peer's idea of our local
484 IPv6 interface identifier, even if the local IPv6 interface
485 identifier was specified in an option.
486 ipv6cp-accept-remote
488 With this option, pppd will accept the peer's idea of its (re‐
489 mote) IPv6 interface identifier, even if the remote IPv6 inter‐
490 face identifier was specified in an option.
491 ipv6cp-max-configure n
493 Set the maximum number of IPv6CP configure-request transmissions
494 to n (default 10).
495 ipv6cp-max-failure n
497 Set the maximum number of IPv6CP configure-NAKs returned before
498 starting to send configure-Rejects instead to n (default 10).
499 ipv6cp-max-terminate n
501 Set the maximum number of IPv6CP terminate-request transmissions
502 to n (default 3).
503 ipv6cp-restart n
505 Set the IPv6CP restart interval (retransmission timeout) to n
506 seconds (default 3).
507 ipx Enable the IPXCP and IPX protocols. This option is presently
509 only supported under Linux, and only if your kernel has been
510 configured to include IPX support.
511 ipx-network n
513 Set the IPX network number in the IPXCP configure request frame
514 to n, a hexadecimal number (without a leading 0x). There is no
515 valid default. If this option is not specified, the network
516 number is obtained from the peer. If the peer does not have the
517 network number, the IPX protocol will not be started.
518 ipx-node n:m
520 Set the IPX node numbers. The two node numbers are separated
521 from each other with a colon character. The first number n is
522 the local node number. The second number m is the peer's node
523 number. Each node number is a hexadecimal number, at most 10
524 digits long. The node numbers on the ipx-network must be unique.
525 There is no valid default. If this option is not specified then
526 the node numbers are obtained from the peer.
527 ipx-router-name <string>
529 Set the name of the router. This is a string and is sent to the
530 peer as information data.
531 ipx-routing n
533 Set the routing protocol to be received by this option. More
534 than one instance of ipx-routing may be specified. The 'none'
535 option (0) may be specified as the only instance of ipx-routing.
536 The values may be 0 for NONE, 2 for RIP/SAP, and 4 for NLSP.
537 ipxcp-accept-local
539 Accept the peer's NAK for the node number specified in the
540 ipx-node option. If a node number was specified, and non-zero,
541 the default is to insist that the value be used. If you include
542 this option then you will permit the peer to override the entry
543 of the node number.
544 ipxcp-accept-network
546 Accept the peer's NAK for the network number specified in the
547 ipx-network option. If a network number was specified, and non-
548 zero, the default is to insist that the value be used. If you
549 include this option then you will permit the peer to override
550 the entry of the node number.
551 ipxcp-accept-remote
553 Use the peer's network number specified in the configure request
554 frame. If a node number was specified for the peer and this op‐
555 tion was not specified, the peer will be forced to use the value
556 which you have specified.
557 ipxcp-max-configure n
559 Set the maximum number of IPXCP configure request frames which
560 the system will send to n. The default is 10.
561 ipxcp-max-failure n
563 Set the maximum number of IPXCP NAK frames which the local sys‐
564 tem will send before it rejects the options. The default value
565 is 3.
566 ipxcp-max-terminate n
568 Set the maximum number of IPXCP terminate request frames before
569 the local system considers that the peer is not listening to
570 them. The default value is 3.
571 kdebug n
573 Enable debugging code in the kernel-level PPP driver. The argu‐
574 ment values depend on the specific kernel driver, but in general
575 a value of 1 will enable general kernel debug messages. (Note
576 that these messages are usually only useful for debugging the
577 kernel driver itself.) For the Linux 2.2.x kernel driver, the
578 value is a sum of bits: 1 to enable general debug messages, 2 to
579 request that the contents of received packets be printed, and 4
580 to request that the contents of transmitted packets be printed.
581 On most systems, messages printed by the kernel are logged by
582 syslog(1) to a file as directed in the /etc/syslog.conf configu‐
583 ration file.
584 key keyfile
586 (EAP-TLS) Use the file keyfile as the private key file (in PEM
587 format), needed for setting up an EAP-TLS connection. This op‐
588 tion is used on the client-side in conjunction with the ca and
589 cert options.
590 ktune Enables pppd to alter kernel settings as appropriate. Under
592 Linux, pppd will enable IP forwarding (i.e. set
593 /proc/sys/net/ipv4/ip_forward to 1) if the proxyarp option is
594 used, and will enable the dynamic IP address option (i.e. set
595 /proc/sys/net/ipv4/ip_dynaddr to 1) in demand mode if the local
596 address changes.
597 lcp-echo-adaptive
599 If this option is used with the lcp-echo-failure option then
600 pppd will send LCP echo-request frames only if no traffic was
601 received from the peer since the last echo-request was sent.
602 lcp-echo-failure n
604 If this option is given, pppd will presume the peer to be dead
605 if n LCP echo-requests are sent without receiving a valid LCP
606 echo-reply. If this happens, pppd will terminate the connec‐
607 tion. Use of this option requires a non-zero value for the
608 lcp-echo-interval parameter. This option can be used to enable
609 pppd to terminate after the physical connection has been broken
610 (e.g., the modem has hung up) in situations where no hardware
611 modem control lines are available.
612 lcp-echo-interval n
614 If this option is given, pppd will send an LCP echo-request
615 frame to the peer every n seconds. Normally the peer should re‐
616 spond to the echo-request by sending an echo-reply. This option
617 can be used with the lcp-echo-failure option to detect that the
618 peer is no longer connected.
619 lcp-max-configure n
621 Set the maximum number of LCP configure-request transmissions to
622 n (default 10).
623 lcp-max-failure n
625 Set the maximum number of LCP configure-NAKs returned before
626 starting to send configure-Rejects instead to n (default 10).
627 lcp-max-terminate n
629 Set the maximum number of LCP terminate-request transmissions to
630 n (default 3).
631 lcp-restart n
633 Set the LCP restart interval (retransmission timeout) to n sec‐
634 onds (default 3).
635 linkname name
637 Sets the logical name of the link to name. Pppd will create a
638 file named ppp-name.pid in /var/run (or /etc/ppp on some sys‐
639 tems) containing its process ID. This can be useful in deter‐
640 mining which instance of pppd is responsible for the link to a
641 given peer system. This is a privileged option.
642 local Don't use the modem control lines. With this option, pppd will
644 ignore the state of the CD (Carrier Detect) signal from the mo‐
645 dem and will not change the state of the DTR (Data Terminal
646 Ready) signal. This is the opposite of the modem option.
647 logfd n
649 Send log messages to file descriptor n. Pppd will send log mes‐
650 sages to at most one file or file descriptor (as well as sending
651 the log messages to syslog), so this option and the logfile op‐
652 tion are mutually exclusive. The default is for pppd to send
653 log messages to stdout (file descriptor 1), unless the serial
654 port is already open on stdout.
655 logfile filename
657 Append log messages to the file filename (as well as sending the
658 log messages to syslog). The file is opened with the privileges
659 of the user who invoked pppd, in append mode.
660 login Use the system password database for authenticating the peer us‐
662 ing PAP, and record the user in the system wtmp file. Note that
663 the peer must have an entry in the /etc/ppp/pap-secrets file as
664 well as the system password database to be allowed access. See
665 also the enable-session option.
666 master_detach
668 If multilink is enabled and this pppd process is the multilink
669 bundle master, and the link controlled by this pppd process ter‐
670 minates, this pppd process continues to run in order to maintain
671 the bundle. If the master_detach option has been given, pppd
672 will detach from its controlling terminal in this situation,
673 even if the nodetach option has been given.
674 maxconnect n
676 Terminate the connection when it has been available for network
677 traffic for n seconds (i.e. n seconds after the first network
678 control protocol comes up).
679 maxfail n
681 Terminate after n consecutive failed connection attempts. A
682 value of 0 means no limit. The default value is 10.
683 modem Use the modem control lines. This option is the default. With
685 this option, pppd will wait for the CD (Carrier Detect) signal
686 from the modem to be asserted when opening the serial device
687 (unless a connect script is specified), and it will drop the DTR
688 (Data Terminal Ready) signal briefly when the connection is ter‐
689 minated and before executing the connect script. On Ultrix,
690 this option implies hardware flow control, as for the crtscts
691 option. This is the opposite of the local option.
692 mp Enables the use of PPP multilink; this is an alias for the `mul‐
694 tilink' option. This option is currently only available under
695 Linux.
696 mppe-stateful
698 Allow MPPE to use stateful mode. Stateless mode is still at‐
699 tempted first. The default is to disallow stateful mode.
700 mpshortseq
702 Enables the use of short (12-bit) sequence numbers in multilink
703 headers, as opposed to 24-bit sequence numbers. This option is
704 only available under Linux, and only has any effect if multilink
705 is enabled (see the multilink option).
706 mrru n Sets the Maximum Reconstructed Receive Unit to n. The MRRU is
708 the maximum size for a received packet on a multilink bundle,
709 and is analogous to the MRU for the individual links. This op‐
710 tion is currently only available under Linux, and only has any
711 effect if multilink is enabled (see the multilink option).
712 ms-dns <addr>
714 If pppd is acting as a server for Microsoft Windows clients,
715 this option allows pppd to supply one or two DNS (Domain Name
716 Server) addresses to the clients. The first instance of this
717 option specifies the primary DNS address; the second instance
718 (if given) specifies the secondary DNS address. (This option
719 was present in some older versions of pppd under the name
720 dns-addr.)
721 ms-wins <addr>
723 If pppd is acting as a server for Microsoft Windows or "Samba"
724 clients, this option allows pppd to supply one or two WINS (Win‐
725 dows Internet Name Services) server addresses to the clients.
726 The first instance of this option specifies the primary WINS ad‐
727 dress; the second instance (if given) specifies the secondary
728 WINS address.
729 multilink
731 Enables the use of the PPP multilink protocol. If the peer also
732 supports multilink, then this link can become part of a bundle
733 between the local system and the peer. If there is an existing
734 bundle to the peer, pppd will join this link to that bundle,
735 otherwise pppd will create a new bundle. See the MULTILINK sec‐
736 tion below. This option is currently only available under
737 Linux.
738 name name
740 Set the name of the local system for authentication purposes to
741 name. This is a privileged option. With this option, pppd will
742 use lines in the secrets files which have name as the second
743 field when looking for a secret to use in authenticating the
744 peer. In addition, unless overridden with the user option, name
745 will be used as the name to send to the peer when authenticating
746 the local system to the peer. (Note that pppd does not append
747 the domain name to name.)
748 noaccomp
750 Disable Address/Control compression in both directions (send and
751 receive).
752 need-peer-eap
754 (EAP-TLS) Require the peer to verify our authentication creden‐
755 tials.
756 noauth Do not require the peer to authenticate itself. This option is
758 privileged.
759 nobsdcomp
761 Disables BSD-Compress compression; pppd will not request or
762 agree to compress packets using the BSD-Compress scheme.
763 noccp Disable CCP (Compression Control Protocol) negotiation. This
765 option should only be required if the peer is buggy and gets
766 confused by requests from pppd for CCP negotiation.
767 nocrtscts
769 Disable hardware flow control (i.e. RTS/CTS) on the serial port.
770 If neither the crtscts nor the nocrtscts nor the cdtrcts nor the
771 nocdtrcts option is given, the hardware flow control setting for
772 the serial port is left unchanged.
773 nocdtrcts
775 This option is a synonym for nocrtscts. Either of these options
776 will disable both forms of hardware flow control.
777 nodefaultroute
779 Disable the defaultroute option. The system administrator who
780 wishes to prevent users from adding a default route with pppd
781 can do so by placing this option in the /etc/ppp/options file.
782 noreplacedefaultroute
784 Disable the replacedefaultroute option. This allows to disable a
785 replacedefaultroute option set previously in the configuration.
786 nodefaultroute6
788 Disable the defaultroute6 option. The system administrator who
789 wishes to prevent users from adding a default route with pppd
790 can do so by placing this option in the /etc/ppp/options file.
791 nodeflate
793 Disables Deflate compression; pppd will not request or agree to
794 compress packets using the Deflate scheme.
795 nodetach
797 Don't detach from the controlling terminal. Without this op‐
798 tion, if a serial device other than the terminal on the standard
799 input is specified, pppd will fork to become a background
800 process.
801 noendpoint
803 Disables pppd from sending an endpoint discriminator to the peer
804 or accepting one from the peer (see the MULTILINK section be‐
805 low). This option should only be required if the peer is buggy.
806 noip Disable IPCP negotiation and IP communication. This option
808 should only be required if the peer is buggy and gets confused
809 by requests from pppd for IPCP negotiation.
810 noipv6 Disable IPv6CP negotiation and IPv6 communication. This option
812 should only be required if the peer is buggy and gets confused
813 by requests from pppd for IPv6CP negotiation.
814 noipdefault
816 Disables the default behaviour when no local IP address is spec‐
817 ified, which is to determine (if possible) the local IP address
818 from the hostname. With this option, the peer will have to sup‐
819 ply the local IP address during IPCP negotiation (unless it
820 specified explicitly on the command line or in an options file).
821 noipx Disable the IPXCP and IPX protocols. This option should only be
823 required if the peer is buggy and gets confused by requests from
824 pppd for IPXCP negotiation.
825 noktune
827 Opposite of the ktune option; disables pppd from changing system
828 settings.
829 nolock Opposite of the lock option; specifies that pppd should not cre‐
831 ate a UUCP-style lock file for the serial device. This option
832 is privileged.
833 nolog Do not send log messages to a file or file descriptor. This op‐
835 tion cancels the logfd and logfile options.
836 nomagic
838 Disable magic number negotiation. With this option, pppd cannot
839 detect a looped-back line. This option should only be needed if
840 the peer is buggy.
841 nomp Disables the use of PPP multilink. This option is currently
843 only available under Linux.
844 nomppe Disables MPPE (Microsoft Point to Point Encryption). This is
846 the default.
847 nomppe-40
849 Disable 40-bit encryption with MPPE.
850 nomppe-128
852 Disable 128-bit encryption with MPPE.
853 nomppe-stateful
855 Disable MPPE stateful mode. This is the default.
856 nompshortseq
858 Disables the use of short (12-bit) sequence numbers in the PPP
859 multilink protocol, forcing the use of 24-bit sequence numbers.
860 This option is currently only available under Linux, and only
861 has any effect if multilink is enabled.
862 nomultilink
864 Disables the use of PPP multilink. This option is currently
865 only available under Linux.
866 nopcomp
868 Disable protocol field compression negotiation in both the re‐
869 ceive and the transmit direction.
870 nopersist
872 Exit once a connection has been made and terminated. This is
873 the default unless the persist or demand option has been speci‐
874 fied.
875 nopredictor1
877 Do not accept or agree to Predictor-1 compression.
878 noproxyarp
880 Disable the proxyarp option. The system administrator who
881 wishes to prevent users from creating proxy ARP entries with
882 pppd can do so by placing this option in the /etc/ppp/options
883 file.
884 noremoteip
886 Allow pppd to operate without having an IP address for the peer.
887 This option is only available under Linux. Normally, pppd will
888 request the peer's IP address, and if the peer does not supply
889 it, pppd will use an arbitrary address in the 10.x.x.x subnet.
890 With this option, if the peer does not supply its IP address,
891 pppd will not ask the peer for it, and will not set the destina‐
892 tion address of the ppp interface. In this situation, the ppp
893 interface can be used for routing by creating device routes, but
894 the peer itself cannot be addressed directly for IP traffic.
895 notty Normally, pppd requires a terminal device. With this option,
897 pppd will allocate itself a pseudo-tty master/slave pair and use
898 the slave as its terminal device. Pppd will create a child
899 process to act as a `character shunt' to transfer characters be‐
900 tween the pseudo-tty master and its standard input and output.
901 Thus pppd will transmit characters on its standard output and
902 receive characters on its standard input even if they are not
903 terminal devices. This option increases the latency and CPU
904 overhead of transferring data over the ppp interface as all of
905 the characters sent and received must flow through the character
906 shunt process. An explicit device name may not be given if this
907 option is used.
908 novj Disable Van Jacobson style TCP/IP header compression in both the
910 transmit and the receive direction.
911 novjccomp
913 Disable the connection-ID compression option in Van Jacobson
914 style TCP/IP header compression. With this option, pppd will
915 not omit the connection-ID byte from Van Jacobson compressed
916 TCP/IP headers, nor ask the peer to do so.
917 papcrypt
919 Indicates that all secrets in the /etc/ppp/pap-secrets file
920 which are used for checking the identity of the peer are en‐
921 crypted, and thus pppd should not accept a password which, be‐
922 fore encryption, is identical to the secret from the
923 /etc/ppp/pap-secrets file.
924 pap-max-authreq n
926 Set the maximum number of PAP authenticate-request transmissions
927 to n (default 10).
928 pap-restart n
930 Set the PAP restart interval (retransmission timeout) to n sec‐
931 onds (default 3).
932 pap-timeout n
934 Set the maximum time that pppd will wait for the peer to authen‐
935 ticate itself with PAP to n seconds (0 means no limit).
936 pass-filter filter-expression
938 Specifies a packet filter to applied to data packets being sent
939 or received to determine which packets should be allowed to
940 pass. Packets which are rejected by the filter are silently
941 discarded. This option can be used to prevent specific network
942 daemons (such as routed) using up link bandwidth, or to provide
943 a very basic firewall capability. The filter-expression syntax
944 is as described for tcpdump(1), except that qualifiers which are
945 inappropriate for a PPP link, such as ether and arp, are not
946 permitted. Generally the filter expression should be enclosed
947 in single-quotes to prevent whitespace in the expression from
948 being interpreted by the shell. Note that it is possible to ap‐
949 ply different constraints to incoming and outgoing packets using
950 the inbound and outbound qualifiers. This option is currently
951 only available under Linux, and requires that the kernel was
952 configured to include PPP filtering support (CONFIG_PPP_FILTER).
953 password password-string
955 Specifies the password to use for authenticating to the peer.
956 Use of this option is discouraged, as the password is likely to
957 be visible to other users on the system (for example, by using
958 ps(1)).
959 persist
961 Do not exit after a connection is terminated; instead try to re‐
962 open the connection. The maxfail option still has an effect on
963 persistent connections.
964 plugin filename
966 Load the shared library object file filename as a plugin. This
967 is a privileged option. If filename does not contain a slash
968 (/), pppd will look in the /usr/lib/pppd/version directory for
969 the plugin, where version is the version number of pppd (for ex‐
970 ample, 2.4.2).
971 predictor1
973 Request that the peer compress frames that it sends using Pre‐
974 dictor-1 compression, and agree to compress transmitted frames
975 with Predictor-1 if requested. This option has no effect unless
976 the kernel driver supports Predictor-1 compression.
977 privgroup group-name
979 Allows members of group group-name to use privileged options.
980 This is a privileged option. Use of this option requires care
981 as there is no guarantee that members of group-name cannot use
982 pppd to become root themselves. Consider it equivalent to
983 putting the members of group-name in the kmem or disk group.
984 proxyarp
986 Add an entry to this system's ARP [Address Resolution Protocol]
987 table with the IP address of the peer and the Ethernet address
988 of this system. This will have the effect of making the peer
989 appear to other systems to be on the local ethernet.
990 pty script
992 Specifies that the command script is to be used to communicate
993 rather than a specific terminal device. Pppd will allocate it‐
994 self a pseudo-tty master/slave pair and use the slave as its
995 terminal device. The script will be run in a child process with
996 the pseudo-tty master as its standard input and output. An ex‐
997 plicit device name may not be given if this option is used.
998 (Note: if the record option is used in conjunction with the pty
999 option, the child process will have pipes on its standard input
1000 and output.)
1001 receive-all
1003 With this option, pppd will accept all control characters from
1004 the peer, including those marked in the receive asyncmap. With‐
1005 out this option, pppd will discard those characters as specified
1006 in RFC1662. This option should only be needed if the peer is
1007 buggy.
1008 record filename
1010 Specifies that pppd should record all characters sent and re‐
1011 ceived to a file named filename. This file is opened in append
1012 mode, using the user's user-ID and permissions. This option is
1013 implemented using a pseudo-tty and a process to transfer charac‐
1014 ters between the pseudo-tty and the real serial device, so it
1015 will increase the latency and CPU overhead of transferring data
1016 over the ppp interface. The characters are stored in a tagged
1017 format with timestamps, which can be displayed in readable form
1018 using the pppdump(8) program.
1019 remotename name
1021 Set the assumed name of the remote system for authentication
1022 purposes to name.
1023 remotenumber number
1025 Set the assumed telephone number of the remote system for au‐
1026 thentication purposes to number.
1027 refuse-chap
1029 With this option, pppd will not agree to authenticate itself to
1030 the peer using CHAP.
1031 refuse-mschap
1033 With this option, pppd will not agree to authenticate itself to
1034 the peer using MS-CHAP.
1035 refuse-mschap-v2
1037 With this option, pppd will not agree to authenticate itself to
1038 the peer using MS-CHAPv2.
1039 refuse-eap
1041 With this option, pppd will not agree to authenticate itself to
1042 the peer using EAP.
1043 refuse-pap
1045 With this option, pppd will not agree to authenticate itself to
1046 the peer using PAP.
1047 require-chap
1049 Require the peer to authenticate itself using CHAP [Challenge
1050 Handshake Authentication Protocol] authentication.
1051 require-mppe
1053 Require the use of MPPE (Microsoft Point to Point Encryption).
1054 This option disables all other compression types. This option
1055 enables both 40-bit and 128-bit encryption. In order for MPPE
1056 to successfully come up, you must have authenticated with either
1057 MS-CHAP or MS-CHAPv2. This option is presently only supported
1058 under Linux, and only if your kernel has been configured to in‐
1059 clude MPPE support.
1060 require-mppe-40
1062 Require the use of MPPE, with 40-bit encryption.
1063 require-mppe-128
1065 Require the use of MPPE, with 128-bit encryption.
1066 require-mschap
1068 Require the peer to authenticate itself using MS-CHAP [Microsoft
1069 Challenge Handshake Authentication Protocol] authentication.
1070 require-mschap-v2
1072 Require the peer to authenticate itself using MS-CHAPv2 [Micro‐
1073 soft Challenge Handshake Authentication Protocol, Version 2] au‐
1074 thentication.
1075 require-eap
1077 Require the peer to authenticate itself using EAP [Extensible
1078 Authentication Protocol] authentication.
1079 require-pap
1081 Require the peer to authenticate itself using PAP [Password Au‐
1082 thentication Protocol] authentication.
1083 set name=value
1085 Set an environment variable for scripts that are invoked by
1086 pppd. When set by a privileged source, the variable specified
1087 by name cannot be changed by options contained in an unprivi‐
1088 leged source. See also the unset option and the environment de‐
1089 scribed in SCRIPTS.
1090 show-password
1092 When logging the contents of PAP packets, this option causes
1093 pppd to show the password string in the log message.
1094 silent With this option, pppd will not transmit LCP packets to initiate
1096 a connection until a valid LCP packet is received from the peer
1097 (as for the `passive' option with ancient versions of pppd).
1098 srp-interval n
1100 If this parameter is given and pppd uses EAP SRP-SHA1 to authen‐
1101 ticate the peer (i.e., is the server), then pppd will use the
1102 optional lightweight SRP rechallenge mechanism at intervals of n
1103 seconds. This option is faster than eap-interval reauthentica‐
1104 tion because it uses a hash-based mechanism and does not derive
1105 a new session key.
1106 srp-pn-secret string
1108 Set the long-term pseudonym-generating secret for the server.
1109 This value is optional and if set, needs to be known at the
1110 server (authenticator) side only, and should be different for
1111 each server (or poll of identical servers). It is used along
1112 with the current date to generate a key to encrypt and decrypt
1113 the client's identity contained in the pseudonym.
1114 srp-use-pseudonym
1116 When operating as an EAP SRP-SHA1 client, attempt to use the
1117 pseudonym stored in ~/.ppp_pseudonym first as the identity, and
1118 save in this file any pseudonym offered by the peer during au‐
1119 thentication.
1120 stop-bits n
1122 Set the number of stop bits for the serial port. Valid values
1123 are 1 or 2. The default value is 1.
1124 sync Use synchronous HDLC serial encoding instead of asynchronous.
1126 The device used by pppd with this option must have sync support.
1127 Currently supports Microgate SyncLink adapters under Linux and
1128 FreeBSD 2.2.8 and later.
1129 unit num
1131 Sets the ppp unit number (for a ppp0 or ppp1 etc interface name)
1132 for outbound connections. If the unit is already in use a dy‐
1133 namically allocated number will be used.
1134 ifname string
1136 Set the ppp interface name for outbound connections. If the in‐
1137 terface name is already in use, or if the name cannot be used
1138 for any other reason, pppd will terminate.
1139 unset name
1141 Remove a variable from the environment variable for scripts that
1142 are invoked by pppd. When specified by a privileged source, the
1143 variable name cannot be set by options contained in an unprivi‐
1144 leged source. See also the set option and the environment de‐
1145 scribed in SCRIPTS.
1146 updetach
1148 With this option, pppd will detach from its controlling terminal
1149 once it has successfully established the ppp connection (to the
1150 point where the first network control protocol, usually the IP
1151 control protocol, has come up).
1152 up_sdnotify
1154 Use this option to run pppd in systemd service units of Type=no‐
1155 tify (up_sdnotify implies nodetach). When up_sdnotify is en‐
1156 abled, pppd will notify systemd once it has successfully estab‐
1157 lished the ppp connection (to the point where the first network
1158 control protocl, usually the IP control protocol, has come up).
1159 This option is only availble when pppd is compiled with systemd
1160 support.
1161 usehostname
1163 Enforce the use of the hostname (with domain name appended, if
1164 given) as the name of the local system for authentication pur‐
1165 poses (overrides the name option). This option is not normally
1166 needed since the name option is privileged.
1167 usepeerdns
1169 Ask the peer for up to 2 DNS server addresses. The addresses
1170 supplied by the peer (if any) are passed to the /etc/ppp/ip-up
1171 script in the environment variables DNS1 and DNS2, and the envi‐
1172 ronment variable USEPEERDNS will be set to 1. In addition, pppd
1173 will create an /var/run/ppp/resolv.conf file containing one or
1174 two nameserver lines with the address(es) supplied by the peer.
1175 user name
1177 Sets the name used for authenticating the local system to the
1178 peer to name.
1179 vj-max-slots n
1181 Sets the number of connection slots to be used by the Van Jacob‐
1182 son TCP/IP header compression and decompression code to n, which
1183 must be between 2 and 16 (inclusive).
1184 welcome script
1186 Run the executable or shell command specified by script before
1187 initiating PPP negotiation, after the connect script (if any)
1188 has completed. A value for this option from a privileged source
1189 cannot be overridden by a non-privileged user.
1190 xonxoff
1192 Use software flow control (i.e. XON/XOFF) to control the flow of
1193 data on the serial port.
1194
1196 To establish PPP link over Ethernet (PPPoE) it is needed to load pppd's
1197 plugin pppoe.so and then specify option nic-interface instead of modem
1198 options ttyname and speed. Recognized pppd's PPPoE options are:
1199 nic-interface
1201 Use the ethernet device interface to communicate with the peer.
1202 For example, establishing PPPoE link on eth0 interface is done
1203 by specifying ppp'd option nic-eth0. Prefix nic- for this option
1204 may be avoided if interface name is unambiguous and does not
1205 look like any other pppd's option.
1206 pppoe-service name
1208 Connect to specified PPPoE service name. For backward compati‐
1209 bility also rp_pppoe_service option name is supported.
1210 pppoe-ac name
1212 Connect to specified PPPoE access concentrator name. For back‐
1213 ward compatibility also rp_pppoe_ac option name is supported.
1214 pppoe-sess sessid:macaddr
1216 Attach to existing PPPoE session. For backward compatibility
1217 also rp_pppoe_sess option name is supported.
1218 pppoe-verbose n
1220 Be verbose about discovered access concentrators. For backward
1221 compatibility also rp_pppoe_verbose option name is supported.
1222 pppoe-mac macaddr
1224 Connect to specified MAC address.
1225 pppoe-host-uniq string
1227 Set the PPPoE Host-Uniq tag to the supplied hex string. By de‐
1228 fault PPPoE Host-Uniq tag is set to the pppd's process PID. For
1229 backward compatibility this option may be specified without pp‐
1230 poe- prefix.
1231 pppoe-padi-timeout n
1233 Initial timeout for discovery packets in seconds (default 5).
1234 pppoe-padi-attempts n
1236 Number of discovery attempts (default 3).
1237
1239 Options can be taken from files as well as the command line. Pppd
1240 reads options from the files /etc/ppp/options, ~/.ppprc and
1241 /etc/ppp/options.ttyname (in that order) before processing the options
1242 on the command line. (In fact, the command-line options are scanned to
1243 find the terminal name before the options.ttyname file is read.) In
1244 forming the name of the options.ttyname file, the initial /dev/ is re‐
1245 moved from the terminal name, and any remaining / characters are re‐
1246 placed with dots.
1247 An options file is parsed into a series of words, delimited by white‐
1249 space. Whitespace can be included in a word by enclosing the word in
1250 double-quotes ("). A backslash (\) quotes the following character. A
1251 hash (#) starts a comment, which continues until the end of the line.
1252 There is no restriction on using the file or call options within an op‐
1253 tions file.
1254
1256 pppd provides system administrators with sufficient access control that
1257 PPP access to a server machine can be provided to legitimate users
1258 without fear of compromising the security of the server or the network
1259 it's on. This control is provided through restrictions on which IP ad‐
1260 dresses the peer may use, based on its authenticated identity (if any),
1261 and through restrictions on which options a non-privileged user may
1262 use. Several of pppd's options are privileged, in particular those
1263 which permit potentially insecure configurations; these options are
1264 only accepted in files which are under the control of the system admin‐
1265 istrator, or if pppd is being run by root.
1266 The default behaviour of pppd is to allow an unauthenticated peer to
1268 use a given IP address only if the system does not already have a route
1269 to that IP address. For example, a system with a permanent connection
1270 to the wider internet will normally have a default route, and thus all
1271 peers will have to authenticate themselves in order to set up a connec‐
1272 tion. On such a system, the auth option is the default. On the other
1273 hand, a system where the PPP link is the only connection to the inter‐
1274 net will not normally have a default route, so the peer will be able to
1275 use almost any IP address without authenticating itself.
1276 As indicated above, some security-sensitive options are privileged,
1278 which means that they may not be used by an ordinary non-privileged
1279 user running a setuid-root pppd, either on the command line, in the
1280 user's ~/.ppprc file, or in an options file read using the file option.
1281 Privileged options may be used in /etc/ppp/options file or in an op‐
1282 tions file read using the call option. If pppd is being run by the
1283 root user, privileged options can be used without restriction.
1284 When opening the device, pppd uses either the invoking user's user ID
1286 or the root UID (that is, 0), depending on whether the device name was
1287 specified by the user or the system administrator. If the device name
1288 comes from a privileged source, that is, /etc/ppp/options or an options
1289 file read using the call option, pppd uses full root privileges when
1290 opening the device. Thus, by creating an appropriate file under
1291 /etc/ppp/peers, the system administrator can allow users to establish a
1292 ppp connection via a device which they would not normally have permis‐
1293 sion to access. Otherwise pppd uses the invoking user's real UID when
1294 opening the device.
1295
1297 Authentication is the process whereby one peer convinces the other of
1298 its identity. This involves the first peer sending its name to the
1299 other, together with some kind of secret information which could only
1300 come from the genuine authorized user of that name. In such an ex‐
1301 change, we will call the first peer the "client" and the other the
1302 "server". The client has a name by which it identifies itself to the
1303 server, and the server also has a name by which it identifies itself to
1304 the client. Generally the genuine client shares some secret (or pass‐
1305 word) with the server, and authenticates itself by proving that it
1306 knows that secret. Very often, the names used for authentication cor‐
1307 respond to the internet hostnames of the peers, but this is not essen‐
1308 tial.
1309 At present, pppd supports three authentication protocols: the Password
1311 Authentication Protocol (PAP), Challenge Handshake Authentication Pro‐
1312 tocol (CHAP), and Extensible Authentication Protocol (EAP). PAP in‐
1313 volves the client sending its name and a cleartext password to the
1314 server to authenticate itself. In contrast, the server initiates the
1315 CHAP authentication exchange by sending a challenge to the client (the
1316 challenge packet includes the server's name). The client must respond
1317 with a response which includes its name plus a hash value derived from
1318 the shared secret and the challenge, in order to prove that it knows
1319 the secret. EAP supports CHAP-style authentication, and also includes
1320 the SRP-SHA1 mechanism, which is resistant to dictionary-based attacks
1321 and does not require a cleartext password on the server side.
1322 The PPP protocol, being symmetrical, allows both peers to require the
1324 other to authenticate itself. In that case, two separate and indepen‐
1325 dent authentication exchanges will occur. The two exchanges could use
1326 different authentication protocols, and in principle, different names
1327 could be used in the two exchanges.
1328 The default behaviour of pppd is to agree to authenticate if requested,
1330 and to not require authentication from the peer. However, pppd will
1331 not agree to authenticate itself with a particular protocol if it has
1332 no secrets which could be used to do so.
1333 Pppd stores secrets for use in authentication in secrets files
1335 (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for CHAP, MS-CHAP,
1336 MS-CHAPv2, and EAP MD5-Challenge, and /etc/ppp/srp-secrets for EAP
1337 SRP-SHA1). All secrets files have the same format. The secrets files
1338 can contain secrets for pppd to use in authenticating itself to other
1339 systems, as well as secrets for pppd to use when authenticating other
1340 systems to itself.
1341 Each line in a secrets file contains one secret. A given secret is
1343 specific to a particular combination of client and server - it can only
1344 be used by that client to authenticate itself to that server. Thus
1345 each line in a secrets file has at least 3 fields: the name of the
1346 client, the name of the server, and the secret. These fields may be
1347 followed by a list of the IP addresses that the specified client may
1348 use when connecting to the specified server.
1349 A secrets file is parsed into words as for a options file, so the
1351 client name, server name and secrets fields must each be one word, with
1352 any embedded spaces or other special characters quoted or escaped.
1353 Note that case is significant in the client and server names and in the
1354 secret.
1355 If the secret starts with an `@', what follows is assumed to be the
1357 name of a file from which to read the secret. A "*" as the client or
1358 server name matches any name. When selecting a secret, pppd takes the
1359 best match, i.e. the match with the fewest wildcards.
1360 Any following words on the same line are taken to be a list of accept‐
1362 able IP addresses for that client. If there are only 3 words on the
1363 line, or if the first word is "-", then all IP addresses are disal‐
1364 lowed. To allow any address, use "*". A word starting with "!" indi‐
1365 cates that the specified address is not acceptable. An address may be
1366 followed by "/" and a number n, to indicate a whole subnet, i.e. all
1367 addresses which have the same value in the most significant n bits. In
1368 this form, the address may be followed by a plus sign ("+") to indicate
1369 that one address from the subnet is authorized, based on the ppp net‐
1370 work interface unit number in use. In this case, the host part of the
1371 address will be set to the unit number plus one.
1372 Thus a secrets file contains both secrets for use in authenticating
1374 other hosts, plus secrets which we use for authenticating ourselves to
1375 others. When pppd is authenticating the peer (checking the peer's
1376 identity), it chooses a secret with the peer's name in the first field
1377 and the name of the local system in the second field. The name of the
1378 local system defaults to the hostname, with the domain name appended if
1379 the domain option is used. This default can be overridden with the
1380 name option, except when the usehostname option is used. (For EAP
1381 SRP-SHA1, see the srp-entry(8) utility for generating proper validator
1382 entries to be used in the "secret" field.)
1383 When pppd is choosing a secret to use in authenticating itself to the
1385 peer, it first determines what name it is going to use to identify it‐
1386 self to the peer. This name can be specified by the user with the user
1387 option. If this option is not used, the name defaults to the name of
1388 the local system, determined as described in the previous paragraph.
1389 Then pppd looks for a secret with this name in the first field and the
1390 peer's name in the second field. Pppd will know the name of the peer
1391 if CHAP or EAP authentication is being used, because the peer will have
1392 sent it in the challenge packet. However, if PAP is being used, pppd
1393 will have to determine the peer's name from the options specified by
1394 the user. The user can specify the peer's name directly with the re‐
1395 motename option. Otherwise, if the remote IP address was specified by
1396 a name (rather than in numeric form), that name will be used as the
1397 peer's name. Failing that, pppd will use the null string as the peer's
1398 name.
1399 When authenticating the peer with PAP, the supplied password is first
1401 compared with the secret from the secrets file. If the password
1402 doesn't match the secret, the password is encrypted using crypt() and
1403 checked against the secret again. Thus secrets for authenticating the
1404 peer can be stored in encrypted form if desired. If the papcrypt op‐
1405 tion is given, the first (unencrypted) comparison is omitted, for bet‐
1406 ter security.
1407 Furthermore, if the login option was specified, the username and pass‐
1409 word are also checked against the system password database. Thus, the
1410 system administrator can set up the pap-secrets file to allow PPP ac‐
1411 cess only to certain users, and to restrict the set of IP addresses
1412 that each user can use. Typically, when using the login option, the
1413 secret in /etc/ppp/pap-secrets would be "", which will match any pass‐
1414 word supplied by the peer. This avoids the need to have the same se‐
1415 cret in two places.
1416 Authentication must be satisfactorily completed before IPCP (or any
1418 other Network Control Protocol) can be started. If the peer is re‐
1419 quired to authenticate itself, and fails to do so, pppd will terminated
1420 the link (by closing LCP). If IPCP negotiates an unacceptable IP ad‐
1421 dress for the remote host, IPCP will be closed. IP packets can only be
1422 sent or received when IPCP is open.
1423 In some cases it is desirable to allow some hosts which can't authenti‐
1425 cate themselves to connect and use one of a restricted set of IP ad‐
1426 dresses, even when the local host generally requires authentication.
1427 If the peer refuses to authenticate itself when requested, pppd takes
1428 that as equivalent to authenticating with PAP using the empty string
1429 for the username and password. Thus, by adding a line to the pap-se‐
1430 crets file which specifies the empty string for the client and pass‐
1431 word, it is possible to allow restricted access to hosts which refuse
1432 to authenticate themselves.
1433
1435 When IPCP negotiation is completed successfully, pppd will inform the
1436 kernel of the local and remote IP addresses for the ppp interface.
1437 This is sufficient to create a host route to the remote end of the
1438 link, which will enable the peers to exchange IP packets. Communica‐
1439 tion with other machines generally requires further modification to
1440 routing tables and/or ARP (Address Resolution Protocol) tables. In
1441 most cases the defaultroute and/or proxyarp options are sufficient for
1442 this, but in some cases further intervention is required. The
1443 /etc/ppp/ip-up script can be used for this.
1444 Sometimes it is desirable to add a default route through the remote
1446 host, as in the case of a machine whose only connection to the Internet
1447 is through the ppp interface. The defaultroute option causes pppd to
1448 create such a default route when IPCP comes up, and delete it when the
1449 link is terminated.
1450 In some cases it is desirable to use proxy ARP, for example on a server
1452 machine connected to a LAN, in order to allow other hosts to communi‐
1453 cate with the remote host. The proxyarp option causes pppd to look for
1454 a network interface on the same subnet as the remote host (an interface
1455 supporting broadcast and ARP, which is up and not a point-to-point or
1456 loopback interface). If found, pppd creates a permanent, published ARP
1457 entry with the IP address of the remote host and the hardware address
1458 of the network interface found.
1459 When the demand option is used, the interface IP addresses have already
1461 been set at the point when IPCP comes up. If pppd has not been able to
1462 negotiate the same addresses that it used to configure the interface
1463 (for example when the peer is an ISP that uses dynamic IP address as‐
1464 signment), pppd has to change the interface IP addresses to the negoti‐
1465 ated addresses. This may disrupt existing connections, and the use of
1466 demand dialling with peers that do dynamic IP address assignment is not
1467 recommended.
1468
1470 Multilink PPP provides the capability to combine two or more PPP links
1471 between a pair of machines into a single `bundle', which appears as a
1472 single virtual PPP link which has the combined bandwidth of the indi‐
1473 vidual links. Currently, multilink PPP is only supported under Linux.
1474 Pppd detects that the link it is controlling is connected to the same
1476 peer as another link using the peer's endpoint discriminator and the
1477 authenticated identity of the peer (if it authenticates itself). The
1478 endpoint discriminator is a block of data which is hopefully unique for
1479 each peer. Several types of data can be used, including locally-as‐
1480 signed strings of bytes, IP addresses, MAC addresses, randomly strings
1481 of bytes, or E-164 phone numbers. The endpoint discriminator sent to
1482 the peer by pppd can be set using the endpoint option.
1483 In some circumstances the peer may send no endpoint discriminator or a
1485 non-unique value. The bundle option adds an extra string which is
1486 added to the peer's endpoint discriminator and authenticated identity
1487 when matching up links to be joined together in a bundle. The bundle
1488 option can also be used to allow the establishment of multiple bundles
1489 between the local system and the peer. Pppd uses a TDB database in
1490 /var/run/pppd2.tdb to match up links.
1491 Assuming that multilink is enabled and the peer is willing to negotiate
1493 multilink, then when pppd is invoked to bring up the first link to the
1494 peer, it will detect that no other link is connected to the peer and
1495 create a new bundle, that is, another ppp network interface unit. When
1496 another pppd is invoked to bring up another link to the peer, it will
1497 detect the existing bundle and join its link to it.
1498 If the first link terminates (for example, because of a hangup or a re‐
1500 ceived LCP terminate-request) the bundle is not destroyed unless there
1501 are no other links remaining in the bundle. Rather than exiting, the
1502 first pppd keeps running after its link terminates, until all the links
1503 in the bundle have terminated. If the first pppd receives a SIGTERM or
1504 SIGINT signal, it will destroy the bundle and send a SIGHUP to the pppd
1505 processes for each of the links in the bundle. If the first pppd re‐
1506 ceives a SIGHUP signal, it will terminate its link but not the bundle.
1507 Note: demand mode is not currently supported with multilink.
1509
1511 The following examples assume that the /etc/ppp/options file contains
1512 the auth option (as in the default /etc/ppp/options file in the ppp
1513 distribution).
1514 Probably the most common use of pppd is to dial out to an ISP. This
1516 can be done with a command such as
1517 pppd call isp
1519 where the /etc/ppp/peers/isp file is set up by the system administrator
1521 to contain something like this:
1522 ttyS0 19200 crtscts
1524 connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'
1525 noauth
1526 In this example, we are using chat to dial the ISP's modem and go
1528 through any logon sequence required. The /etc/ppp/chat-isp file con‐
1529 tains the script used by chat; it could for example contain something
1530 like this:
1531 ABORT "NO CARRIER"
1533 ABORT "NO DIALTONE"
1534 ABORT "ERROR"
1535 ABORT "NO ANSWER"
1536 ABORT "BUSY"
1537 ABORT "Username/Password Incorrect"
1538 "" "at"
1539 OK "at&d0&c1"
1540 OK "atdt2468135"
1541 "name:" "^Umyuserid"
1542 "word:" "\qmypassword"
1543 "ispts" "\q^Uppp"
1544 "~-^Uppp-~"
1545 See the chat(8) man page for details of chat scripts.
1547 Pppd can also be used to provide a dial-in ppp service for users. If
1549 the users already have login accounts, the simplest way to set up the
1550 ppp service is to let the users log in to their accounts and run pppd
1551 (installed setuid-root) with a command such as
1552 pppd proxyarp
1554 To allow a user to use the PPP facilities, you need to allocate an IP
1556 address for that user's machine and create an entry in /etc/ppp/pap-se‐
1557 crets, /etc/ppp/chap-secrets, or /etc/ppp/srp-secrets (depending on
1558 which authentication method the PPP implementation on the user's ma‐
1559 chine supports), so that the user's machine can authenticate itself.
1560 For example, if Joe has a machine called "joespc" that is to be allowed
1561 to dial in to the machine called "server" and use the IP address joe‐
1562 spc.my.net, you would add an entry like this to /etc/ppp/pap-secrets or
1563 /etc/ppp/chap-secrets:
1564 joespc server "joe's secret" joespc.my.net
1566 (See srp-entry(8) for a means to generate the server's entry when
1568 SRP-SHA1 is in use.) Alternatively, you can create a username called
1569 (for example) "ppp", whose login shell is pppd and whose home directory
1570 is /etc/ppp. Options to be used when pppd is run this way can be put
1571 in /etc/ppp/.ppprc.
1572 If your serial connection is any more complicated than a piece of wire,
1574 you may need to arrange for some control characters to be escaped. In
1575 particular, it is often useful to escape XON (^Q) and XOFF (^S), using
1576 asyncmap a0000. If the path includes a telnet, you probably should es‐
1577 cape ^] as well (asyncmap 200a0000). If the path includes an rlogin,
1578 you will need to use the escape ff option on the end which is running
1579 the rlogin client, since many rlogin implementations are not transpar‐
1580 ent; they will remove the sequence [0xff, 0xff, 0x73, 0x73, followed by
1581 any 8 bytes] from the stream.
1582
1584 Messages are sent to the syslog daemon using facility LOG_DAEMON.
1585 (This can be overridden by recompiling pppd with the macro LOG_PPP de‐
1586 fined as the desired facility.) See the syslog(8) documentation for
1587 details of where the syslog daemon will write the messages. On most
1588 systems, the syslog daemon uses the /etc/syslog.conf file to specify
1589 the destination(s) for syslog messages. You may need to edit that file
1590 to suit.
1591 The debug option causes the contents of all control packets sent or re‐
1593 ceived to be logged, that is, all LCP, PAP, CHAP, EAP, or IPCP packets.
1594 This can be useful if the PPP negotiation does not succeed or if au‐
1595 thentication fails. If debugging is enabled at compile time, the debug
1596 option also causes other debugging messages to be logged.
1597 Debugging can also be enabled or disabled by sending a SIGUSR1 signal
1599 to the pppd process. This signal acts as a toggle.
1600
1602 The exit status of pppd is set to indicate whether any error was de‐
1603 tected, or the reason for the link being terminated. The values used
1604 are:
1605 0 Pppd has detached, or otherwise the connection was successfully
1607 established and terminated at the peer's request.
1608 1 An immediately fatal error of some kind occurred, such as an es‐
1610 sential system call failing, or running out of virtual memory.
1611 2 An error was detected in processing the options given, such as
1613 two mutually exclusive options being used.
1614 3 Pppd is not setuid-root and the invoking user is not root.
1616 4 The kernel does not support PPP, for example, the PPP kernel
1618 driver is not included or cannot be loaded.
1619 5 Pppd terminated because it was sent a SIGINT, SIGTERM or SIGHUP
1621 signal.
1622 6 The serial port could not be locked.
1624 7 The serial port could not be opened.
1626 8 The connect script failed (returned a non-zero exit status).
1628 9 The command specified as the argument to the pty option could
1630 not be run.
1631 10 The PPP negotiation failed, that is, it didn't reach the point
1633 where at least one network protocol (e.g. IP) was running.
1634 11 The peer system failed (or refused) to authenticate itself.
1636 12 The link was established successfully and terminated because it
1638 was idle.
1639 13 The link was established successfully and terminated because the
1641 connect time limit was reached.
1642 14 Callback was negotiated and an incoming call should arrive
1644 shortly.
1645 15 The link was terminated because the peer is not responding to
1647 echo requests.
1648 16 The link was terminated by the modem hanging up.
1650 17 The PPP negotiation failed because serial loopback was detected.
1652 18 The init script failed (returned a non-zero exit status).
1654 19 We failed to authenticate ourselves to the peer.
1656
1658 Pppd invokes scripts at various stages in its processing which can be
1659 used to perform site-specific ancillary processing. These scripts are
1660 usually shell scripts, but could be executable code files instead.
1661 Pppd does not wait for the scripts to finish (except for the ip-pre-up
1662 script). The scripts are executed as root (with the real and effective
1663 user-id set to 0), so that they can do things such as update routing
1664 tables or run privileged daemons. Be careful that the contents of
1665 these scripts do not compromise your system's security. Pppd runs the
1666 scripts with standard input, output and error redirected to /dev/null,
1667 and with an environment that is empty except for some environment vari‐
1668 ables that give information about the link. The environment variables
1669 that pppd sets are:
1670 DEVICE The name of the serial tty device being used.
1672 IFNAME The name of the network interface being used.
1674 IPLOCAL
1676 The IP address for the local end of the link. This is only set
1677 when IPCP has come up.
1678 IPREMOTE
1680 The IP address for the remote end of the link. This is only set
1681 when IPCP has come up.
1682 PEERNAME
1684 The authenticated name of the peer. This is only set if the
1685 peer authenticates itself.
1686 SPEED The baud rate of the tty device.
1688 ORIG_UID
1690 The real user-id of the user who invoked pppd.
1691 PPPLOGNAME
1693 The username of the real user-id that invoked pppd. This is al‐
1694 ways set.
1695 For the ip-down and auth-down scripts, pppd also sets the following
1697 variables giving statistics for the connection:
1698 CONNECT_TIME
1700 The number of seconds from when the PPP negotiation started un‐
1701 til the connection was terminated.
1702 BYTES_SENT
1704 The number of bytes sent (at the level of the serial port) dur‐
1705 ing the connection.
1706 BYTES_RCVD
1708 The number of bytes received (at the level of the serial port)
1709 during the connection.
1710 LINKNAME
1712 The logical name of the link, set with the linkname option.
1713 CALL_FILE
1715 The value of the call option.
1716 DNS1 If the peer supplies DNS server addresses, this variable is set
1718 to the first DNS server address supplied (whether or not the
1719 usepeerdns option was given).
1720 DNS2 If the peer supplies DNS server addresses, this variable is set
1722 to the second DNS server address supplied (whether or not the
1723 usepeerdns option was given).
1724 Pppd invokes the following scripts, if they exist. It is not an error
1726 if they don't exist.
1727 /etc/ppp/auth-up
1729 A program or script which is executed after the remote system
1730 successfully authenticates itself. It is executed with the pa‐
1731 rameters
1732 interface-name peer-name user-name tty-device speed
1734 Note that this script is not executed if the peer doesn't au‐
1736 thenticate itself, for example when the noauth option is used.
1737 /etc/ppp/auth-down
1739 A program or script which is executed when the link goes down,
1740 if /etc/ppp/auth-up was previously executed. It is executed in
1741 the same manner with the same parameters as /etc/ppp/auth-up.
1742 /etc/ppp/ip-pre-up
1744 A program or script which is executed just before the ppp net‐
1745 work interface is brought up. It is executed with the same pa‐
1746 rameters as the ip-up script (below). At this point the inter‐
1747 face exists and has IP addresses assigned but is still down.
1748 This can be used to add firewall rules before any IP traffic can
1749 pass through the interface. Pppd will wait for this script to
1750 finish before bringing the interface up, so this script should
1751 run quickly.
1752 /etc/ppp/ip-up
1754 A program or script which is executed when the link is available
1755 for sending and receiving IP packets (that is, IPCP has come
1756 up). It is executed with the parameters
1757 interface-name tty-device speed local-IP-address remote-IP-ad‐
1759 dress ipparam
1760 /etc/ppp/ip-down
1762 A program or script which is executed when the link is no longer
1763 available for sending and receiving IP packets. This script can
1764 be used for undoing the effects of the /etc/ppp/ip-up and
1765 /etc/ppp/ip-pre-up scripts. It is invoked in the same manner
1766 and with the same parameters as the ip-up script.
1767 /etc/ppp/ipv6-up
1769 Like /etc/ppp/ip-up, except that it is executed when the link is
1770 available for sending and receiving IPv6 packets. It is executed
1771 with the parameters
1772 interface-name tty-device speed local-link-local-address re‐
1774 mote-link-local-address ipparam
1775 /etc/ppp/ipv6-down
1777 Similar to /etc/ppp/ip-down, but it is executed when IPv6 pack‐
1778 ets can no longer be transmitted on the link. It is executed
1779 with the same parameters as the ipv6-up script.
1780 /etc/ppp/ipx-up
1782 A program or script which is executed when the link is available
1783 for sending and receiving IPX packets (that is, IPXCP has come
1784 up). It is executed with the parameters
1785 interface-name tty-device speed network-number lo‐
1787 cal-IPX-node-address remote-IPX-node-address local-IPX-rout‐
1788 ing-protocol remote-IPX-routing-protocol local-IPX-router-name
1789 remote-IPX-router-name ipparam pppd-pid
1790 The local-IPX-routing-protocol and remote-IPX-routing-protocol
1792 field may be one of the following:
1793 NONE to indicate that there is no routing protocol
1795 RIP to indicate that RIP/SAP should be used
1796 NLSP to indicate that Novell NLSP should be used
1797 RIP NLSP to indicate that both RIP/SAP and NLSP should be used
1798 /etc/ppp/ipx-down
1800 A program or script which is executed when the link is no longer
1801 available for sending and receiving IPX packets. This script
1802 can be used for undoing the effects of the /etc/ppp/ipx-up
1803 script. It is invoked in the same manner and with the same pa‐
1804 rameters as the ipx-up script.
1805
1807 /var/run/pppn.pid (BSD or Linux), /etc/ppp/pppn.pid (others)
1808 Process-ID for pppd process on ppp interface unit n.
1809 /var/run/ppp-name.pid (BSD or Linux),
1811 /etc/ppp/ppp-name.pid (others) Process-ID for pppd process for
1812 logical link name (see the linkname option).
1813 /var/run/pppd2.tdb
1815 Database containing information about pppd processes, interfaces
1816 and links, used for matching links to bundles in multilink oper‐
1817 ation. May be examined by external programs to obtain informa‐
1818 tion about running pppd instances, the interfaces and devices
1819 they are using, IP address assignments, etc. /etc/ppp/pap-se‐
1820 crets Usernames, passwords and IP addresses for PAP authentica‐
1821 tion. This file should be owned by root and not readable or
1822 writable by any other user. Pppd will log a warning if this is
1823 not the case.
1824 /etc/ppp/chap-secrets
1826 Names, secrets and IP addresses for CHAP/MS-CHAP/MS-CHAPv2 au‐
1827 thentication. As for /etc/ppp/pap-secrets, this file should be
1828 owned by root and not readable or writable by any other user.
1829 Pppd will log a warning if this is not the case.
1830 /etc/ppp/srp-secrets
1832 Names, secrets, and IP addresses for EAP authentication. As for
1833 /etc/ppp/pap-secrets, this file should be owned by root and not
1834 readable or writable by any other user. Pppd will log a warning
1835 if this is not the case.
1836 ~/.ppp_pseudonym
1838 Saved client-side SRP-SHA1 pseudonym. See the srp-use-pseudonym
1839 option for details.
1840 /etc/ppp/options
1842 System default options for pppd, read before user default op‐
1843 tions or command-line options.
1844 ~/.ppprc
1846 User default options, read before /etc/ppp/options.ttyname.
1847 /etc/ppp/options.ttyname
1849 System default options for the serial port being used, read af‐
1850 ter ~/.ppprc. In forming the ttyname part of this filename, an
1851 initial /dev/ is stripped from the port name (if present), and
1852 any slashes in the remaining part are converted to dots.
1853 /etc/ppp/peers
1855 A directory containing options files which may contain privi‐
1856 leged options, even if pppd was invoked by a user other than
1857 root. The system administrator can create options files in this
1858 directory to permit non-privileged users to dial out without re‐
1859 quiring the peer to authenticate, but only to certain trusted
1860 peers.
1861
1863 chat(8), pppstats(8)
1864 RFC1144
1866 Jacobson, V. Compressing TCP/IP headers for low-speed serial
1867 links. February 1990.
1868 RFC1321
1870 Rivest, R. The MD5 Message-Digest Algorithm. April 1992.
1871 RFC1332
1873 McGregor, G. PPP Internet Protocol Control Protocol (IPCP).
1874 May 1992.
1875 RFC1334
1877 Lloyd, B.; Simpson, W.A. PPP authentication protocols. October
1878 1992.
1879 RFC1661
1881 Simpson, W.A. The Point-to-Point Protocol (PPP). July 1994.
1882 RFC1662
1884 Simpson, W.A. PPP in HDLC-like Framing. July 1994.
1885 RFC1990
1887 Sklower, K.; et al., The PPP Multilink Protocol (MP). August
1888 1996.
1889 RFC2284
1891 Blunk, L.; Vollbrecht, J., PPP Extensible Authentication Proto‐
1892 col (EAP). March 1998.
1893 RFC2472
1895 Haskin, D. IP Version 6 over PPP December 1998.
1896 RFC2945
1898 Wu, T., The SRP Authentication and Key Exchange System September
1899 2000.
1900 draft-ietf-pppext-eap-srp-03.txt
1902 Carlson, J.; et al., EAP SRP-SHA1 Authentication Protocol. July
1903 2001.
1904
1906 Some limited degree of control can be exercised over a running pppd
1907 process by sending it a signal from the list below.
1908 SIGINT, SIGTERM
1910 These signals cause pppd to terminate the link (by closing LCP),
1911 restore the serial device settings, and exit. If a connector or
1912 disconnector process is currently running, pppd will send the
1913 same signal to its process group, so as to terminate the connec‐
1914 tor or disconnector process.
1915 SIGHUP This signal causes pppd to terminate the link, restore the se‐
1917 rial device settings, and close the serial device. If the per‐
1918 sist or demand option has been specified, pppd will try to re‐
1919 open the serial device and start another connection (after the
1920 holdoff period). Otherwise pppd will exit. If this signal is
1921 received during the holdoff period, it causes pppd to end the
1922 holdoff period immediately. If a connector or disconnector
1923 process is running, pppd will send the same signal to its
1924 process group.
1925 SIGUSR1
1927 This signal toggles the state of the debug option.
1928 SIGUSR2
1930 This signal causes pppd to renegotiate compression. This can be
1931 useful to re-enable compression after it has been disabled as a
1932 result of a fatal decompression error. (Fatal decompression er‐
1933 rors generally indicate a bug in one or other implementation.)
1934
1937 Paul Mackerras (paulus@samba.org), based on earlier work by Drew
1938 Perkins, Brad Clements, Karl Fox, Greg Christy, and Brad Parker.
1939
1942 Pppd is copyrighted and made available under conditions which provide
1943 that it may be copied and used in source or binary forms provided that
1944 the conditions listed below are met. Portions of pppd are covered by
1945 the following copyright notices:
1946 Copyright (c) 1984-2000 Carnegie Mellon University. All rights re‐
1948 served.
1949 Copyright (c) 1993-2004 Paul Mackerras. All rights reserved.
1950 Copyright (c) 1995 Pedro Roque Marques. All rights reserved.
1951 Copyright (c) 1995 Eric Rosenquist. All rights reserved.
1952 Copyright (c) 1999 Tommi Komulainen. All rights reserved.
1953 Copyright (C) Andrew Tridgell 1999
1954 Copyright (c) 2000 by Sun Microsystems, Inc. All rights reserved.
1955 Copyright (c) 2001 by Sun Microsystems, Inc. All rights reserved.
1956 Copyright (c) 2002 Google, Inc. All rights reserved.
1957 The copyright notices contain the following statements.
1959 Redistribution and use in source and binary forms, with or without mod‐
1961 ification, are permitted provided that the following conditions are
1962 met:
1963 1. Redistributions of source code must retain the above copyright
1965 notice, this list of conditions and the following disclaimer.
1966 2. Redistributions in binary form must reproduce the above copyright
1968 notice, this list of conditions and the following disclaimer in
1969 the documentation and/or other materials provided with the
1970 distribution.
1971 3. The name "Carnegie Mellon University" must not be used to
1973 endorse or promote products derived from this software without
1974 prior written permission. For permission or any legal
1975 details, please contact
1976 Office of Technology Transfer
1977 Carnegie Mellon University
1978 5000 Forbes Avenue
1979 Pittsburgh, PA 15213-3890
1980 (412) 268-4387, fax: (412) 268-7395
1981 tech-transfer@andrew.cmu.edu
1982 3b. The name(s) of the authors of this software must not be used to
1984 endorse or promote products derived from this software without
1985 prior written permission.
1986 4. Redistributions of any form whatsoever must retain the following
1988 acknowledgements:
1989 "This product includes software developed by Computing Services
1990 at Carnegie Mellon University (http://www.cmu.edu/computing/)."
1991 "This product includes software developed by Paul Mackerras
1992 <paulus@samba.org>".
1993 "This product includes software developed by Pedro Roque Marques
1994 <pedro_m@yahoo.com>".
1995 "This product includes software developed by Tommi Komulainen
1996 <Tommi.Komulainen@iki.fi>".
1997 CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
1999 SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FIT‐
2000 NESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE FOR ANY
2001 SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
2002 RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
2003 CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
2004 CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
2005 THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
2007 THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
2008 FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDI‐
2009 RECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
2010 LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLI‐
2011 GENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH
2012 THE USE OR PERFORMANCE OF THIS SOFTWARE.
2013 PPPD(8)