>We can access other machine without putting password every time. ssh provide option to put user public key as authorized key on machine which user want to access without entering password every time.
Following simple steps are required to do this
(press enter whenever ask for passphrase)
ssh-keygen generate private(id_rsa) and public key(id_rsa.pub) file for that user (here root)
Now put root public key file (id_rsa.pub) on machine which you want to access (here machine with ip 192.168.11.51)
root@machine1#ssh-copy-id -i /root/.ssh/id_rsa.pub email@example.com
enter “yes” if ask for adding machine
specify password for root user of 192.168.11.51 whenever ask ..
cheers, setup is complete now, now access it