Two useful SSH shortcuts

Like many people working with servers, I use SSH connections a lot, and there are two basic configurations that can save a lot of time: (1) Creating aliases for different connections and (2) Saving the password so that you do not have to enter it every time you establish a connection.

The first part is easy. For instance, suppose I want to type ssh thales instead of ssh blondin@thales.math.uqam.ca every time I connect to the server hosting my personal webpage. Then I have to edit (or create if it does not exist) the file ~/.ssh/config and add the following lines:

Host thales
User blondin
HostName thales.math.uqam.ca

The next part is a bit more complicated. First, you need to enter the commande ssh-keygen. It will ask you to save the key into the file ~/.ssh/id_rsa by default. When this is done, it suffices to append the content of the file ~/.ssh/id_rsa.pub to the .ssh/authorized_keys file on the remote host. This might be done by entering the following one-liner:

cat ~/.ssh/id_rsa.pub | ssh thales 'cat >> .ssh/authorized_keys'

Of course, you need to replace thales by the host you set up in the SSH configuration file.