How to Set Up SSH Aliases - SSH Config#

vim ~/.ssh/config

You can have as many entries as you like

Create a public key entry#

Host somealias
    Port 22
    User someuser
    IdentityFile ~/.ssh/id_example
    IdentitiesOnly yes

Create a password authentication entry#

Host anotheralias
    User anotheruser
    PubKeyAuthentication no

Use the alias#

ssh somealias

ssh anotheralias

source: Servers for Hackers - SSH Tricks