Russell91 / Sshmux

Usage

sshmux adds the -s argument to ssh, which makes your sessions more robust by hosting server sessions in tmux and adding client side reconnect logic. The simplest usage (which requires tmux on the server) is:

$ sshmux [email protected] -s sessionname

Once the connection is established, it is persistent. You can turn close your laptop and put it to sleep, restart your wifi connection, or put your laptop in your backpack and go home for the day. When you open it back up, the connection will be automatically reestablished. Sshmux is a simple bash wrapper around ssh. It is platform independent, works with all other ssh command line arguments, and requires no configuration. Without the -s argument, sshmux behaves identically to ssh, letting you alias ssh=sshmux without any problems.

Installation

$ wget https://raw.githubusercontent.com/Russell91/sshmux/master/sshmux && 
chmod +x sshmux && 
sudo mv sshmux /usr/local/bin #or anywhere else on your PATH

Details

Named Sessions

You do not need to know tmux to use sshmux for persistent ssh sessions. But if you do know tmux, you'll immediately notice that sshmux creates a tmux session with the name "default" by default. If you want to create a second tmux session with the name "session2", you can use the -s flag as in tmux attach -s session2:

$ sshmux [email protected] -s session2

This will create a new session if no session beginning with the letters "session2" exists, and join an existing session otherwise. The original -s flag of ssh is not supported when using sshmux (sshmux already uses this flag internally).

List available sessions

If you're trying to remember what sessions are already open on the server, you can use the --ls flag, as in:

$ sshmux [email protected] --ls

This will run 'tmux ls' on the server, print the results to your local terminal, and exit.

Debugging

If sshmux isn't connecting well, you can pass it the -v flag for more verbose output, as you would do with ssh.

What to do if your server doesn't have tmux

You can install tmux without root using a script such as https://github.com/jealie/install_tmux/blob/master/install_tmux.sh. sshmux then allows you to supply a PATH variable of directories in which to search for tmux using the --tmux-path argument. For example, if tmux is installed to one server on /home/user/local/bin/tmux, you could use:

$ sshmux --tmux-path /home/user/local/bin [email protected]

Note that --tmux-path simply appends the supplied string to the $PATH variable before calling tmux, so the above command will also work on a different server where tmux was not installed to that directory, but just exists in /usr/bin/tmux. Thus, if you do find yourself needing to install tmux from source on some servers, you can add something like `alias sshmux='sshmux --tmux-path /path/for/server1:/path/for/server2' and avoid typing out --tmux-path by hand.

Comparison to other tools

sshmux is related to autossh and mosh. Like sshmux, autossh will automatically attempt to reconnect the client when wifi is restarted. However, unlike sshmux, autossh does not provide server side persistence by default.

Mosh is another tool supporting persistent ssh sessions, having additional features including immediate local rendering of keyboard inputs and UDP connections for improved performance. However, the UDP feature requires the user to reconfigure the server's firewall prior to using mosh. This requirement adds significant overhead to setting up mosh on a new server, and is in many cases not satisfiable in commercial environments.

Unlike both autossh and mosh, sshmux has no binary distribution and is instead a bash wrapper, exposing exactly the same flags and features as the traditional ssh tool.