ssh ProxyCommand

If you need to tunnel through a machine to get to another one, using ssh, you can easily do this with a ProxyCommand entry in your .ssh/config:

Host foo
ProxyCommand ssh <gateway-machine> -W <target-machine>:%p

If you have avahi-daemon installed on your gateway machine, you can get even better:

Host foo.local
ProxyCommand ssh <gateway-machine> -W %h:%p

I use this to get access to my office machine(s), without having to worry about firing up a VPN. I can rewrite the hostname so that I don’t need to have a different entry for each machine in the office:

Host *.office
ProxyCommand ssh <gateway-machine> -W $(echo %h | sed s/.office/.local/):%p

Bingo, now I can get really simple access to any machine in the office (as long as it has avahi installed, or is a Mac).

matt@alpaca:~ $ ssh
Last login: Fri May 23 19:52:29 2014 from
matt@karma:~ $