Read on for instructions setting up two-factor auth for SSH logins under Ubuntu. I used 11.04 Natty Narwhal; other releases may require small tweaks.
Post tagged: ssh
For my most recent backup scheme, I needed to lock down rsync over OpenSSH while allowing scheduled syncing. I did it using the authorized_keys command="command" option to restrict access for a specific private key.
Three other people will find this useful.