SSH config
- http://linux.die.net/man/5/ssh_config
- http://nerderati.com/2011/03/simplify-your-life-with-an-ssh-config-file/
Tips
MacOS ssh-agent behavior
Host *
UseKeychain yes
AddKeysToAgent yes
IdentityFile ~/.ssh/id_rsa
Host *
UseKeychain yes
AddKeysToAgent yes
IdentityFile ~/.ssh/id_rsa