1MOSH(1) General Commands Manual MOSH(1)
2
6 mosh - mobile shell with roaming and intelligent local echo
7
9 mosh [options] [--] [user@]host [command...]
10
12 mosh (mobile shell) is a remote terminal application that supports
13 intermittent connectivity, allows roaming, and provides speculative
14 local echo and line editing of user keystrokes.
15 Compared with ssh, mosh is more robust — its connections stay up across
17 sleeps and changes in the client's IP address — and more responsive,
18 because the protocol is tolerant of packet loss and the client can echo
19 most keystrokes immediately, without waiting for a network round-trip.
20 mosh uses ssh to establish a connection to the remote host and authen‐
22 ticate with existing means (e.g., public-key authentication or a pass‐
23 word). mosh executes the unprivileged mosh-server helper program on the
24 server, then closes the SSH connection and starts the mosh-client,
25 which establishes a long-lived datagram connection over UDP.
26 To improve responsiveness, mosh runs a predictive model of the server's
28 behavior in the background, trying to guess the effect of each key‐
29 stroke on the screen. It makes predictions for normal typing,
30 backspace, and the left- and right-arrow keys. When it is confident,
31 mosh displays the predictions without waiting for the server. The pre‐
32 dictive model must prove itself anew on each row of the terminal and
33 after each control character, so mosh avoids echoing passwords or non-
34 echoing editor commands.
35 By default, mosh shows its predictions only on high-latency connections
37 and to smooth out network glitches. (On longer-latency links, the pre‐
38 dicted cells are underlined until confirmed by the server.) Occasional
39 echo mistakes are corrected within a network round-trip and do not
40 cause lasting effect.
41 mosh does not support X forwarding or the non-interactive uses of SSH,
43 including port forwarding or sshfs. mosh works through typical client-
44 side network address translators but requires UDP to pass between
45 client and server. By default, mosh uses the ports between 60000 and
46 61000, but allows the user to request a particular UDP port instead.
47 Currently, mosh has limited support for IPv6, dual-stack networks, and
49 servers with multiple addresses. At session start, it will select a
50 single IPv4 or IPv6 server address to connect to for the lifetime of
51 the session.
52 mosh will do its best to arrange a UTF-8 character set locale on the
54 client and server. The client must have locale-related environment
55 variables that specify UTF-8. mosh will pass these client variables to
56 the mosh-server on its command line, but in most cases they will not
57 need to be used. mosh-server first attempts to use its own locale-
58 related environment variables, which come from the system default con‐
59 figuration (sometimes /etc/default/locale) or from having been passed
60 over the SSH connection. But if these variables don't call for the use
61 of UTF-8, mosh-server will apply the locale-related environment vari‐
62 ables from the client and try again.
63
66 Options named --experimental-* are subject to change or removal in
67 future versions of Mosh; their design or function is not yet final.
68 command
71 Command to run on remote host. By default, mosh executes a login
72 shell.
73 --client=PATH
76 path to client helper on local machine (default: "mosh-client")
77 --server=COMMAND
80 command to run server helper on remote machine (default: "mosh-
81 server")
82 The server helper is unprivileged and can be installed in the
84 user's home directory.
85 This option can be used to set environment variables for the
87 server by using the env(1) command to wrap the actual server
88 command. See mosh-server(1) for available environment vari‐
89 ables.
90 --ssh=COMMAND
93 OpenSSH command to remotely execute mosh-server on remote
94 machine (default: "ssh")
95 An alternate ssh port can be specified with, e.g., --ssh="ssh -p
97 2222".
98 --ssh-pty
101 --no-ssh-pty Enable or disable ssh's use of a pty when connect‐
102 ing to a remote host. The default is enabled.
103 --predict=WHEN
106 Controls use of speculative local echo. WHEN defaults to `adap‐
107 tive' (show predictions on slower links and to smooth out net‐
108 work glitches) and can also be `always` or `never'.
109 The MOSH_PREDICTION_DISPLAY environment variable controls this
111 setting permanently and can adopt the same three values.
112 Even on `always', mosh will only show predictions when it is
114 confident. This generally means a previous prediction on the
115 same row of the terminal has been confirmed by the server, with‐
116 out any intervening control character keystrokes.
117 -a Synonym for --predict=always
120 -n Synonym for --predict=never
123 --family=inet
126 Only use IPv4 for the SSH connection and Mosh session.
127 --family=inet6
130 Only use IPv6 for the SSH connection and Mosh session. This and
131 the following modes require Perl's IO::Socket::IP or
132 IO::Socket::INET6 modules.
133 --family=auto
136 Autodetect IPv4 or IPv6 for hosts that only have addresses in a
137 single family. Hosts with both IPv4 and IPv6 addresses will
138 raise an error, and require re-invocation of mosh with another
139 --family option.
140 --family=all
143 Choose an address from all available IPv4 or IPv6 address, even
144 for dual-stack hosts. This is the most convenient option, but
145 requires dual-stack connectivity, and Mosh 1.2.5 or later on the
146 server, when roaming with dual-stack servers.
147 --family=prefer-inet
150 Similar to --family=all, but attempt connects to the IPv4
151 addresses first. This is the default.
152 --family=prefer-inet6
155 Similar to --family=all, but attempt connects to the IPv6
156 addresses first.
157 -4 Synonym for --family=inet
160 -6 Synonym for --family=inet6
163 -p PORT[:PORT2], --port=PORT[:PORT2]
166 Use a particular server-side UDP port or port range, for exam‐
167 ple, if this is the only port that is forwarded through a fire‐
168 wall to the server. With -p 0, the server will let the operating
169 system pick an available UDP port. Otherwise, mosh will choose a
170 port between 60000 and 61000. Please note that this option does
171 not affect the server-side port used by SSH.
172 --bind-server={ssh|any|IP}
175 Control the IP address that the mosh-server binds to.
176 The default is `ssh', in which case the server will reply from
178 the IP address that the SSH connection came from (as found in
179 the SSH_CONNECTION environment variable). This is useful for
180 multihomed servers.
181 With --bind-server=any, the server will reply on the default
183 interface and will not bind to a particular IP address. This can
184 be useful if the connection is made through sslh or another tool
185 that makes the SSH connection appear to come from localhost.
186 With --bind-server=IP, the server will attempt to bind to the
188 specified IP address.
189 --no-init
192 Do not send the smcup initialization string and rmcup deinitial‐
193 ization string to the client's terminal. On many terminals this
194 disables alternate screen mode.
195 --local
198 Invoke mosh-server locally, without using ssh. This option
199 requires the host argument to be a local, numeric IPv4/IPv6
200 address. This option is useful for testing.
201 --experimental-remote-ip={proxy|local|remote}
204 Select the method used to discover the IP address that the mosh-
205 client connects to.
206 The default is proxy, which uses SSH's --ssh-proxy-command
208 option to generate and report the exact address that ssh uses to
209 connect to the remote host. This option is generally the most
210 compatible with hosts and other options configured in ssh con‐
211 figuration files. However, this may not work for some configu‐
212 rations, or for environments where a ssh bastion host forwards
213 to a remote machine. It only works with OpenSSH.
214 With remote, the server's SSH_CONNECTION environment variable
216 will be used. This is useful for environments where ssh for‐
217 warding is used, or the --ssh-proxy-command option is used for
218 other purposes.
219 With local, Mosh resolves the hostname given on its command
221 line, and uses that address for both ssh and Mosh connections.
222 This option ignores any configuration in ssh_config for the same
223 hostname.
224
227 The default escape character used by Mosh is ASCII RS (decimal 30).
228 This is typically typed as Ctrl-^ or Ctrl-Shift-6, on US English key‐
229 boards. Users of non-English keyboards may find it difficult or impos‐
230 sible to type the default escape character, and may need to change the
231 escape character. See the description of MOSH_ESCAPE_KEY, below. In
232 this description, the configured escape character is represented as
233 Esc.
234 There are two slightly different modes for escape sequences, depending
236 whether the escape character is printable or not.
237 If the escape character is a printable character, it must be prefixed
239 with a newline, similar to OpenSSH. To send the escape character
240 itself, type it twice. If the escape character is set to ~, mosh will
241 behave much like OpenSSH.
242 If the escape character is a non-printable control character, no prefix
244 is used and the escape character is recognized at any time. To send
245 the escape character itself, type the escape character, then its corre‐
246 sponding ASCII character (for Ctrl-^ you would type ^, for Ctrl-B you
247 would type B).
248 The escape sequence to shut down the connection is Esc .. The sequence
250 Esc Ctrl-Z suspends the client. Any other sequence passes both charac‐
251 ters through to the server.
252
255 These variables are not actually interpreted by mosh(1) itself, but are
256 passed through to mosh-server(1). They are described here for ease of
257 use.
258 MOSH_ESCAPE_KEY
261 When set, this configures the escape character used for local
262 commands. The escape character may be set to any ASCII charac‐
263 ter in the range 1-127. The variable must be set with a single
264 literal ASCII character. Control characters are set with the
265 actual ASCII control character, not with a printable representa‐
266 tion such as "^B".
267 MOSH_PREDICTION_DISPLAY
270 Controls local echo as described above. The command-line flag
271 overrides this variable.
272 MOSH_TITLE_NOPREFIX
275 When set, inhibits prepending "[mosh]" to window title.
276
279 mosh-client(1), mosh-server(1).
280 Project home page: https://mosh.org
282
285 mosh was written by Keith Winstein <mosh-devel@mit.edu>.
286
288 Please report bugs to mosh-devel@mit.edu. Users may also subscribe to
289 the mosh-users@mit.edu mailing list, at
290 http://mailman.mit.edu/mailman/listinfo/mosh-users
291 April 2013 MOSH(1)