SSH Key Based, Password Less Login

It can be very handy to be able to login to an SSH shell without supplying a password. Here's how.

Firstly, on your client machine, generate a keypair. If you are using Windows you can do this using PuTTYgen. If you are on a Nix machine issue:

ssh-keygen -t dsa

Next up, we need to copy the public key to the server. If you are on Linux you can use scp to do this:

cd .ssh/
scp id_dsa.pub server_user_name@server.address:./id_dsa.pub

If you are on Windows you could use sftp or similar to transfer the key across. You should end up with a file called id_dsa.pub in your home directory on the server.

Now, on the server, with your regular user account:

cd .ssh
touch authorized_keys2
chmod 600 authorized_keys2
cat ../id_dsa.pub >> authorized_keys2
rm ../id_dsa.pub

Now, on Windows fire up a PuTTY session specifying the private key under SSH -> Auth. On Nix, simply give:

ssh -l server_user_name server.address

With any luck, you will be sorted for password-less login!

SSH Key Based, Password Less Login was originally published by Martin Paul Eve at eve.gd: Martin Paul Eve on December 07, 2008.