Configuration for the ssh client

For remote work (i.e. not in LAN) I find the following settings helpful.

Host *
    ServerAliveInterval 60
    ForwardX11 yes
    ControlMaster auto
    ControlPath ~/.ssh/ssh_mux_%h_%p_%r
    Compression yes

I’ve placed them in ~/.ssh/config. Here’s a quick walkthrough (man ssh_config has all the details`):

Host *

For all hosts where I login

    ServerAliveInterval 60

Send a package every 60 seconds, so the connection doesn’t timeout.

    ForwardX11 yes

Allow me to start GUI applications remotely (same as ssh -X). See caveat at the end.

    ControlMaster auto
    ControlPath ~/.ssh/ssh_mux_%h_%p_%r

The first connection to each host opens a reusable socket in ~/.ssh/. When I open another connection it will check for such a socket and use it. Speeds up the connection initiation time and removes the password prompt for all but the first connection to a host.

    Compression yes

Compress the data (stdin/out/err and X-forwarding). I haven’t measured this but maybe it helps.

Caveat: If you get messages like

X11 forwarding request failed on channel 1

then you are accessing a host via ssh that does not allow for X forwarding, but you tried it due to ForwardX11 yes. For me this happened with git pull, which uses ssh under the hood. To be honest, it took a while until I understood why the message came.

Solution: Exclude the host that doesn’t support X forwarding:

Host *
    ServerAliveInterval 60
    ControlMaster auto
    ControlPath ~/.ssh/ssh_mux_%h_%p_%r
    Compression yes
Host * !some.server.com
    ForwardX11 yes