manpagez: man pages & more
man mosh(1)
Home | html | info | man
mosh(1)                                                                mosh(1)




NAME

       mosh - mobile shell with roaming and intelligent local echo


SYNOPSIS

       mosh [options] [--] [user@]host [command...]


DESCRIPTION

       mosh  (mobile  shell)  is  a  remote terminal application that supports
       intermittent connectivity, allows  roaming,  and  provides  speculative
       local echo and line editing of user keystrokes.

       Compared  with  ssh,  mosh  is  more  robust -- its connections stay up
       across sleeps and changes in  the  client's  IP  address  --  and  more
       responsive,  because  the  protocol  is tolerant of packet loss and the
       client can echo most keystrokes immediately, without waiting for a net-
       work round-trip.

       mosh  uses ssh to establish a connection to the remote host and authen-
       ticate with existing means (e.g., public-key authentication or a  pass-
       word). mosh executes the unprivileged mosh-server helper program on the
       server, then closes the SSH  connection  and  starts  the  mosh-client,
       which establishes a long-lived datagram connection over UDP.

       To improve responsiveness, mosh runs a predictive model of the server's
       behavior in the background, trying to guess the  effect  of  each  key-
       stroke   on  the  screen.  It  makes  predictions  for  normal  typing,
       backspace, and the left- and right-arrow keys. When  it  is  confident,
       mosh  displays the predictions without waiting for the server. The pre-
       dictive model must prove itself anew on each row of  the  terminal  and
       after  each control character, so mosh avoids echoing passwords or non-
       echoing editor commands.

       By default, mosh shows its predictions only on high-latency connections
       and  to smooth out network glitches. (On longer-latency links, the pre-
       dicted cells are underlined until confirmed by the server.)  Occasional
       echo  mistakes  are  corrected  within  a network round-trip and do not
       cause lasting effect.

       mosh does not support X forwarding or the non-interactive uses of  SSH,
       including  port forwarding or sshfs. mosh works through typical client-
       side network address translators  but  requires  UDP  to  pass  between
       client  and  server.  By default, mosh uses the ports between 60000 and
       61000, but allows the user to request a particular UDP port instead.

       Currently, mosh has limited support for IPv6, dual-stack networks,  and
       servers  with  multiple  addresses.  At session start, it will select a
       single IPv4 or IPv6 server address to connect to for  the  lifetime  of
       the session.

       mosh  will  do  its best to arrange a UTF-8 character set locale on the
       client and server. The  client  must  have  locale-related  environment
       variables  that specify UTF-8. mosh will pass these client variables to
       the mosh-server on its command line, but in most cases  they  will  not
       need  to  be  used.  mosh-server  first attempts to use its own locale-
       related environment variables, which come from the system default  con-
       figuration  (sometimes  /etc/default/locale) or from having been passed
       over the SSH connection. But if these variables don't call for the  use
       of  UTF-8,  mosh-server will apply the locale-related environment vari-
       ables from the client and try again.



OPTIONS

       Options named  --experimental-* are subject to  change  or  removal  in
       future versions of Mosh; their design or function is not yet final.


       command
              Command to run on remote host. By default, mosh executes a login
              shell.


       --client=PATH
              path to client helper on local machine (default: "mosh-client")


       --server=COMMAND
              command to run server helper on remote machine (default:  "mosh-
              server")

              The  server  helper  is unprivileged and can be installed in the
              user's home directory.

              This option can be used to set  environment  variables  for  the
              server  by  using  the  env(1) command to wrap the actual server
              command.  See mosh-server(1)  for  available  environment  vari-
              ables.


       --ssh=COMMAND
              OpenSSH  command  to  remotely  execute  mosh-server  on  remote
              machine (default: "ssh")

              An alternate ssh port can be specified with, e.g., --ssh="ssh -p
              2222".


       --ssh-pty
              --no-ssh-pty  Enable or disable ssh's use of a pty when connect-
              ing to a remote host.  The default is enabled.


       --predict=WHEN
              Controls use of speculative local echo. WHEN defaults to  `adap-
              tive'  (show  predictions on slower links and to smooth out net-
              work glitches) and can also be `always` or `never'.

              The MOSH_PREDICTION_DISPLAY environment variable  controls  this
              setting permanently and can adopt the same three values.

              Even  on  `always',  mosh  will only show predictions when it is
              confident. This generally means a  previous  prediction  on  the
              same row of the terminal has been confirmed by the server, with-
              out any intervening control character keystrokes.


       -a     Synonym for --predict=always


       -n     Synonym for --predict=never


       --family=inet
              Only use IPv4 for the SSH connection and Mosh session.


       --family=inet6
              Only use IPv6 for the SSH connection and Mosh session.  This and
              the   following   modes   require   Perl's   IO::Socket::IP   or
              IO::Socket::INET6 modules.


       --family=auto
              Autodetect IPv4 or IPv6 for hosts that only have addresses in  a
              single  family.   Hosts  with  both IPv4 and IPv6 addresses will
              raise an error, and require re-invocation of mosh  with  another
              --family option.


       --family=all
              Choose  an address from all available IPv4 or IPv6 address, even
              for dual-stack hosts.  This is the most convenient  option,  but
              requires dual-stack connectivity, and Mosh 1.2.5 or later on the
              server, when roaming with dual-stack servers.


       --family=prefer-inet
              Similar to  --family=all,  but  attempt  connects  to  the  IPv4
              addresses first.  This is the default.


       --family=prefer-inet6
              Similar  to  --family=all,  but  attempt  connects  to  the IPv6
              addresses first.


       -4     Synonym for --family=inet


       -6     Synonym for --family=inet6


       -p PORT[:PORT2], --port=PORT[:PORT2]
              Use a particular server-side UDP port or port range,  for  exam-
              ple,  if this is the only port that is forwarded through a fire-
              wall to the server. With -p 0, the server will let the operating
              system pick an available UDP port. Otherwise, mosh will choose a
              port between 60000 and 61000. Please note that this option  does
              not affect the server-side port used by SSH.


       --bind-server={ssh|any|IP}
              Control the IP address that the mosh-server binds to.

              The  default  is `ssh', in which case the server will reply from
              the IP address that the SSH connection came from  (as  found  in
              the  SSH_CONNECTION  environment  variable).  This is useful for
              multihomed servers.

              With --bind-server=any, the server will  reply  on  the  default
              interface and will not bind to a particular IP address. This can
              be useful if the connection is made through sslh or another tool
              that makes the SSH connection appear to come from localhost.

              With  --bind-server=IP,  the  server will attempt to bind to the
              specified IP address.


       --no-init
              Do not send the smcup initialization string and rmcup deinitial-
              ization  string to the client's terminal. On many terminals this
              disables alternate screen mode.


       --local
              Invoke mosh-server locally,  without  using  ssh.   This  option
              requires  the  host  argument  to  be a local, numeric IPv4/IPv6
              address.  This option is useful for testing.


       --experimental-remote-ip={proxy|local|remote}
              Select the method used to discover the IP address that the mosh-
              client connects to.

              The  default  is  proxy,  which  uses  SSH's --ssh-proxy-command
              option to generate and report the exact address that ssh uses to
              connect  to  the remote host.  This option is generally the most
              compatible with hosts and other options configured in  ssh  con-
              figuration  files.  However, this may not work for some configu-
              rations, or for environments where a ssh bastion  host  forwards
              to a remote machine.  It only works with OpenSSH.

              With  remote,  the  server's SSH_CONNECTION environment variable
              will be used.  This is useful for environments  where  ssh  for-
              warding  is  used, or the --ssh-proxy-command option is used for
              other purposes.

              With local, Mosh resolves the  hostname  given  on  its  command
              line,  and  uses that address for both ssh and Mosh connections.
              This option ignores any configuration in ssh_config for the same
              hostname.



ESCAPE SEQUENCES

       The  default  escape  character  used by Mosh is ASCII RS (decimal 30).
       This is typically typed as Ctrl-^ or Ctrl-Shift-6, on US  English  key-
       boards.  Users of non-English keyboards may find it difficult or impos-
       sible to type the default escape character, and may need to change  the
       escape  character.   See the description of MOSH_ESCAPE_KEY, below.  In
       this description, the configured escape  character  is  represented  as
       Esc.

       There  are two slightly different modes for escape sequences, depending
       whether the escape character is printable or not.

       If the escape character is a printable character, it must  be  prefixed
       with  a  newline,  similar  to  OpenSSH.   To send the escape character
       itself, type it twice.  If the escape character is set to ~, mosh  will
       behave much like OpenSSH.

       If the escape character is a non-printable control character, no prefix
       is used and the escape character is recognized at any  time.   To  send
       the escape character itself, type the escape character, then its corre-
       sponding ASCII character (for Ctrl-^ you would type ^, for  Ctrl-B  you
       would type B).

       The  escape sequence to shut down the connection is Esc .. The sequence
       Esc Ctrl-Z suspends the client.  Any other sequence passes both charac-
       ters through to the server.



ENVIRONMENT VARIABLES

       These variables are not actually interpreted by mosh(1) itself, but are
       passed through to mosh-server(1).  They are described here for ease  of
       use.


       MOSH_ESCAPE_KEY
              When  set,  this  configures the escape character used for local
              commands.  The escape character may be set to any ASCII  charac-
              ter  in the range 1-127.  The variable must be set with a single
              literal ASCII character.  Control characters are  set  with  the
              actual ASCII control character, not with a printable representa-
              tion such as "^B".


       MOSH_PREDICTION_DISPLAY
              Controls local echo as described above.  The  command-line  flag
              overrides this variable.


       MOSH_TITLE_NOPREFIX
              When set, inhibits prepending "[mosh]" to window title.



SEE ALSO

       mosh-client(1), mosh-server(1).

       Project home page: https://mosh.org



AUTHOR

       mosh was written by Keith Winstein <mosh-devel@mit.edu>.


BUGS

       Please  report  bugs to mosh-devel@mit.edu. Users may also subscribe to
       the mosh-users@mit.edu mailing list, at
       http://mailman.mit.edu/mailman/listinfo/mosh-users



                                  April 2013                           mosh(1)

mosh 1.3.2 - Generated Fri May 22 10:28:23 CDT 2020
© manpagez.com 2000-2021
Individual documents may contain additional copyright information.