2048 RSA Automatic SSH Login
There is no reason to be hassled to enter login usernames and password when accessing a terminal via ssh. SSH has built in rsa key authentication mechanisms. First build the private and public keys:
This will create your private and public keys in the .ssh folder in your home folder. You then copy the public key to the .ssh folder on the target system. Use scp for this.
scp .ssh/id_rsa.pub 192.168.0.100:.ssh/authorized_keys2
Change the ip address of the target system accordingly. Then login to the target system and change the ssh daemons configuration file.
sudo nano /etc/ssh/sshd_config
Scroll to the password authentication line, remove the pound sign, and make sure its set to no. Also make sure the daemon uses the authorized_keys2 file as the public key reference. Save the file, exit, and reset the ssh daemon.
sudo /etc/init.d/ssh restart
Now your ssh connections will be automated, and powerfully encrypted. You can remove the id_rsa.pub key from your .ssh directory for total security. Now the public key is only on the target system, and the only way to gain access to that system is via direct login or via the private key on your remote system. You can also transfer the private key to a usb drive, and delete the id_rsa key from the .ssh directory. When connecting via ssh use the -i option to locate the key on the usb drive. For example:
ssh -i /media/drive/id_rsa 192.168.0.100
Now the entire session will only work with the usb key in the drive. Your usb drive will literally be a key, without it there is no access to the target system whatsoever. Also do not loose the usb key, otherwise the only way to access the system will be directly via a terminal.