How to get git to use an ssh (rsh) transport other than "ssh"

Question

Is it possible to get git to use something other than "ssh" as the ssh program? Rsync has a -e option for this purpose, and other interfaces where rsh or ssh can be used as the transport. The particular use case I have is chaining the ssh connection via a bastion host, as direct ssh access to the host from which I'm cloning / pulling is not allowed by the firewall.

The best solution I've come up with so far is to create a directory with a single executable called "ssh" in it, and put that directory at the start of my PATH. The contents of the "ssh" file is:

#!/bin/sh
# If we were being clever we'd look at where we were and just snip that
# off the path.
export PATH=/bin:/usr/bin:/sbin:/usr/sbin
exec ssh bastion.example.org ssh "$@"

This works, but the approach has a number of drawbacks.

Note that the GIT_SSH environment variable doesn't do what I'm after, as you still have to create a script and reference that. Whereas with rysnc's -e option I can do

rsync -e 'ssh -K bastion.example.org ssh' ...

Answer 1

Instead of trying to configure git to use another program, you can configure ssh itself:

On the ~/.ssh/config file, add a new Host section

Host git.example.org
  Username myusername
  ProxyCommand ssh bastion.example.org "nc git.example.org 22"

Then, you just need to point your remote to the "git.example.org" host.

Also, if you are using OpenSSH >= 5.4 and don't want the dependency on netcat on the server, you can use SSH's netcat mode instead:

Host git.example.org
  Username myusername
  ProxyCommand ssh bastion.example.org -W "git.example.org:22"