This is a techniques that enables you to login into a remote Linux machine without having any password challenge. You can immediately logged in your remote linux machine, with a single ssh command.

This technique requires a pair of keys, generated on your local machine. The public key will be placed in the remote machine, and the private key resides on your local machine. During key generation, it will prompt for the key password. You need to leave it empty, for no password login.

This technique is useful for administrators that need to login and manage alot of computers from a single machine. No more hassle to key in password in each of the remote machine. This technique is also useful if you want to make a shell script to transfer a file using scp (Secure Copy). The file will be transfered wthout any password challenge, and will be transfered securely.

First thing to do, generate the key pair on your local machine.

su-bash$ ssh-keygen -t rsa

For the key password, leave it blank

The key pair generated are being store at /home/budihost/.ssh/
The public key, id_rsa.pub need to be transfered into .ssh folder in the remote machine.

su-bash$ ssh server “mkdir .ssh; chmod 0700 .ssh”
su-bash$ scp .ssh/id_rsa.pub server:~/.ssh/authorized_keys

You can now try to login to your remote machine,
su-bash$ ssh -l budihost server
You will be logged in without any password prompt