Just a quick note about using SSH. Recently I had to wipe and re-install Ubuntu. (More on that later.) That meant my ssh private key was wiped as well. In order to replace it, I copied the file from a Windows machine onto my newly installed Linux partition.
When I tried to log into some of my other servers, ssh gave me a warning about lax permissions and refused to log in without my password. Very clever. I never even thought to check the permissions of the file I copied over.
Setting the correct permissions:
chmod 600 ~/.ssh/id_rsa
fixed the problem.