When you’re using SSH frequently throughout your day, I think it’s important to have a ‘comfortable’ environment.
A decent SSH config really delivers on this, here’s an example.

~/.ssh/config

HashKnownHosts no

Host *.example.com
    User scott.daniels
    IdentityFile ~/.ssh/id_scotty

Host *.asecondexample.com
    User contractor
    IdentityFile ~/.ssh/id_contracting

Host 192.168.27.*
    User testenvironment

Host *
    ForwardAgent no
    ForwardX11 no
    ForwardX11Trusted yes
    User ubuntu
    Port 22
    Protocol 2
    ServerAliveInterval 60
    ServerAliveCountMax 30

Currently on Ubuntu, if you want auto-complete to work in the terminal. “HashKnownHosts” must be disabled.
Otherwise the bash auto-complete interprets the known_hosts file correctly.

SSH will work through this file. You can see I am able specify different usernames, and different private keys for different hosts. Wildcards are supported, so it’s easy to target a group of hosts.

This file is the difference between me typing:

ssh [email protected] -i ~/.ssh/id_contracting

OR

ssh web01.as<TAB>

I know which I prefer. 🙂

Bonus Round

Ubuntu and other distros run an SSH agent, its useful.
Use “ssh-add ~/.ssh/my_privatekey” and you won’t need to provide your private key password for each new connection.

You can use “ssh-add -D” to remove it prior to ending your session, if you’re conscious of rogue hands.