Force Rsync Command via SSH but Allow Any Directory

February 21, 2014Updated on April 16, 2024 JS Morisset rsync, SSH, UNIX (Generic)

Recently, I needed to sync several directories on a backup / fail-over server with the same directories on a production server. Rsync over SSH takes care of this, but if you want to tighten security, you must use the “command” restriction in the SSH authorized_keys file — This restricts the authenticated key to running a single command, with a specific set of arguments. For example, let’s look at a typical command that might be run from a backup server to rsync daily database dumps:

backup$ rsync -av --delete -e "ssh -i $HOME/.ssh/prod-rsync-key" \
    prod:/var/lib/mysql/dump/ /var/lib/mysql/dump/

Autossh Startup Script for Multiple Tunnels

December 10, 2012Updated on April 16, 2024 JS Morisset Bash, CentOS, SSH

When an encrypted VPN is not available, the next best solution is usually port-forwarding one or more port(s) through an SSH tunnel. The down-side of SSH is that by itself it cannot maintain a persistent connection — network issues may force the tunnel to stop responding, or even drop completely. Autossh is a small front-end for SSH that can monitor the connection, and restart the tunnel if it drops or stops responding. I found that the startup scripts available for autossh on the internet were a little too basic for my needs — I wanted autossh to start multiple connections, and to start/stop each one individually if I needed — so I wrote my own.