In those 4 simple commands you can setup mutual key exchange between two sshservers by using a single login shell session and single window.
*Just change the IP address examples of (10.10.0.2) to the target of your mutual key exchange. It doesn't matter if the server is on a LAN or WAN (well unless the server is behind a firewall and you cannot SSH into it).
|ssh-keygen -t rsa
cat ~/.ssh/id_rsa.pub|ssh 10.10.0.2 tee -a ~/.ssh/authorized_keys
ssh 10.10.0.2 ssh-keygen -t rsa
ssh 10.10.0.2 cat ~/.ssh/id_rsa.pub |tee -a ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys
If you want to do it the hard way, on both servers you can just run this command:
ssh-keygen -t rsa
Just keep hitting enter, and then copy and paste the contents of:
~/.ssh/id_rsa.pub into the other servers "~/.ssh/authorized_keys" file.
Be careful not to add any extra spaces or line breaks when copying it or it won't work.