If you want to use ssh to connect to another server, using an authorized key instead of a password:

In your home directory:

chmod 700 .ssh  
cd .ssh  
chmod 600 authorized_keys  
ssh-keygen -t rsa -b 2048

For a first-time connection, I tend to do it manually at the command line to get the fingerprint stored:

server1$  ssh server2 

(& vice versa as needed)

Then place the contents of the other host’s pub.key into this authorized_keys file:

ssh-copyid who@where 

Or just copy the string manually.