Secure way to run a script on a remote server without requiring authentication

Question

I'm trying to set up a git post-update hook for my gitosis repository to update a working copy on a remote server. What's the best and most secure way to run a script on the remote server without requiring authentication, since the hook will be running as the gitosis user on one machine, which doesn't have a counterpart on the other machine.

I considered using a public/private keypair without a passphrase, which is what I use to have the script automatically update the working copy on the local server (for gitosis, not ssh), but I'm a little hesitant to use the same key for authentication via ssh since if the private key is somehow compromised an attacker could log in without authenticating. Or am I worrying too much, and is this something that permissions will take care of anyway (private key must be chmod 0600)?

Answer 1

The "best and most secure way" is probably to do a git pull when you use the remote server's working copy, or add the server as a git "remote" & push to it simultaneously.

As an alternative the passwordless public key thing will work. I would suggest using a different key than you use for anything else & setting up SSH to only allow forced commands when you log in with that key (add command="...." to the options part of authorized_keys assuming you're using OpenSSH), that way even if your key is compromised all they can do is update your git repository.

Answer 2

I think the private/public key way is the most common one to do such things. I would make it the same way.