Scenario: You have a web script (php, ruby, python, or so) that need to ssh over a remote machine to do stuff. How you do set up ssh key for the apache deamon user?
After some dig out, here's the steps, mostly taken from (Boredworkers.com):
Make key for apache daemon
1. log in to source server as root
2. create .ssh directory for apache user. Make sure you have the ownership right:
$ mkdir /var/www/.ssh
$ chown -R apache:nobody /var/www/.ssh
3. Generate the ssh-key authentication key as user apache using sudo. Use the default file location and leave empty when prompted for passphrase.
$ sudo -u apache ssh-keygen -t rsa
4. Append apache's public key to destination server
$ sudo -u apache cat .ssh/id_rsa.pub | ssh dest_user@dest_server 'cat >> /var/www/.ssh/authorized_keys'
5. Test the set up. You’ll see that you can now run ssh commands without being prompted for the user password:
$ sudo -u apache ssh dest_user@dest_server