Ssh simple explanation

No matter how many times I configure ssh keys, I rarely have the process go smoothly. It is time to write down how it works so I can get it straight in my head.

Moving pieces

• private key : generate this with ssh-keygen. It must have 0600 permissions and usually lives in ~/.ssh
• public key : generate this with ssh-keygen. It must have 0600 permissions and usually lives in ~/.ssh. This file should be distributed to remote hosts and placed in the authorized keys files to allow ssh access to that remote host.
• authorized keys file : this is a list of users and hosts that have access via ssh to this account
• known hosts file : a list of hosts that have been visited and thus authorized

ssh without passwords for cron

A special private key can be generated without a passphrase. Distribute the public key as normal, but when issuing the ssh command in a script, include the identity (private key) without a passphrase:

ssh -i /home/rday/.ssh/cronkey <remote machine> command

There, that wasn't so hard.