Getting a shell remotely.
WHAT SSH IS
An encrypted connection to a shell on another machine.
WHAT YOU NEED
The address A username A password or a key The port, if it is not the default
WHAT THE BASIC COMMAND IS
ssh followed by user, an at sign, and the host.
WHAT TO ADD FOR A DIFFERENT PORT
The port option, with a capital P in some tools and lowercase in others.
WHAT THE FIRST CONNECTION ASKS
Whether to trust the server's fingerprint.
WHAT THAT MEANS
You are confirming the machine is the one you expect.
WHAT TO DO
Verify it if you can, then accept.
WHAT A CHANGED FINGERPRINT WARNING MEANS
Either the server was rebuilt, or something is intercepting the connection.
WHAT TO DO ABOUT IT
Establish which, before connecting.
WHAT TO NEVER DO
Ignore it because it is inconvenient.
WHAT KEYS PROVIDE OVER PASSWORDS
Far stronger authentication, and no password to be guessed.
HOW THEY WORK
A private key stays with you; a public key sits on the server.
WHAT TO PROTECT
The private key, with a passphrase and restrictive permissions.
WHAT PERMISSIONS THE KEY NEEDS
Readable only by you, or SSH refuses to use it.
WHAT TO DISABLE ONCE KEYS WORK
Password authentication.
