title: Create a passwordless secondary ssh key for setting up a ssh tunnel
body: <p>I need to create a script that automatically setup a ssh tunnel. I think that a dedicated ssh key without password is a good start but I couldn't find if this is possible and how to do it. 
  This key should have limited privileges (only set the tunnel up) but I need another private key (with a password) for myself.</p>
  
  <p>Thanks !</p>