Password Less Login to Servers

If you need to frequently login to some server and you want to implement password less login to that server. How will you do this.

 Step # 1: Generate first ssh key
Type the following command to generate your first public and private key on a local workstation. Next provide the required input or accept the defaults. Please do not change the filename and directory location.
workstation#1 $ ssh-keygen -t dsa
Finally, copy your public key to your remote server using scp
workstation#1 $ scp  /root/.ssh/id_dsa.pub 2^nd workstation

   Step # 2:

a) Login to 2nd workstation

b) Now you have new public key. APPEND this key to the downloaded authorized_keys file using cat command:
workstation#2 $ cat id_dsa.pub >> /root/.ssh/authorized_keys2
chmod 600 /root/.ssh/authorized_keys2

Step #3: Test your setup

Now try to login from Workstation #1 to  #2,. You should not be asked for a password:
workstation#1 $ ssh workstation2

what is the difference between DSA and RSA

RSA and DSA are two different algorithms. RSA can be used both for encrypting and signing, while DSA can only be used for signing. I think DSA is considered more secure if you just want to sign stuff.

The difficulty of cracking RSA and DSA with identical key lengths are the same. RSA keys are not allowed to be exported out of the US which makes DSA preferrable for ssh keys if you want to be a law abiding citizen.