---
name: "mosh-server"
section: "1"
platform: "linux"
package: "mosh"
version: "1.4.0-35"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/mosh-server"
---

# mosh-server(1)

server-side helper for mosh

## NAME

mosh-server - server-side helper for mosh

## SYNOPSIS

**mosh-server** new \[-s\] \[-v\] \[-i *IP*\] \[-p *PORT*\[:*PORT2*\]\] \[-c *COLORS*\] \[-- command...\]\

## DESCRIPTION

**mosh-server** is a helper program for the  **[mosh(1)](/mosh/1.md)** remote terminal application.

**mosh-server** binds to a high UDP port and chooses an encryption key to protect the session. It prints both on standard output, detaches from the terminal, and waits for the **mosh-client** to establish a connection. It will exit if no client has contacted it within 60 seconds.

By default, **mosh-server** binds to a port between 60000 and 61000 and executes the user's login shell.

On platforms with **utempter**, **mosh-server** maintains an entry in the **[utmp(5)](/utmp/5.md)** file to indicate its process ID, whether the session is connected, and the client's current IP address.

**mosh-server** exits when the client terminates the connection.

## OPTIONS

The argument "new" must be first on the command line to use command-line options.

- **-s**

  bind to the local interface used for an incoming SSH connection, given in the **SSH\_CONNECTION** environment variable (for multihomed hosts)

- **-v**

  Print some debugging information even after detaching.  More instances of this flag will result in more debugging information.

- **-i *IP***

  IP address of the local interface to bind (for multihomed hosts)

- **-p *PORT*\[:*PORT2*\]**

  UDP port number or port-range to bind.  **-p 0** will let the operating system pick an available UDP port.

- **-c *COLORS***

  Number of colors to advertise to applications through TERM (e.g. 8, 256)

- **-l *NAME=VALUE***

  Locale-related environment variable to try as part of a fallback environment, if the startup environment does not specify a character set of UTF-8.

## ENVIRONMENT VARIABLES

These variables allow server-side configuration of Mosh's behavior. They may be set by administrators in system login/rc files, /etc/login.conf, or similar mechanisms, or users in their shell's login/rc files.  **mosh-server** passes these variables to the login session and shell that it starts, but changing them there will have no effect.

- **MOSH\_SERVER\_NETWORK\_TMOUT**

  If this variable is set to a positive integer number, it specifies how long (in seconds) **mosh-server** will wait to receive an update from the client before exiting.  Since **mosh** is very useful for mobile clients with intermittent operation and connectivity, we suggest setting this variable to a high value, such as 604800 (one week) or 2592000 (30 days).  Otherwise, **mosh-server** will wait indefinitely for a client to reappear.  This variable is somewhat similar to the **TMOUT** variable found in many Bourne shells. However, it is not a login-session inactivity timeout; it only applies to network connectivity.

- **MOSH\_SERVER\_SIGNAL\_TMOUT**

  If this variable is set to a positive integer number, it specifies how long (in seconds) **mosh-server** will ignore SIGUSR1 while waiting to receive an update from the client.  Otherwise, **SIGUSR1** will always terminate **mosh-server**.  Users and administrators may implement scripts to clean up disconnected Mosh sessions.  With this variable set, a user or administrator can issue

  ```
  $ pkill -SIGUSR1 mosh-server
  ```

  to kill disconnected sessions without killing connected login sessions.

## EXAMPLE

```
$ mosh-server
MOSH CONNECT 60001 UAkFedSsVJs2LfMeKyQB5g
mosh-server (mosh 1.1)
[...] (copyright notice omitted)
[mosh-server detached, pid = 20443]
```

## SEE ALSO

[**mosh**(1)](/mosh/1.md), [**mosh-client**(1)](/mosh-client/1.md).

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*