Secure Shell SSH

Secure Shell SSH

Connect as <user> to remote <host> on specified <port> If you do not specify a username it uses your current username

ssh -p <port> <user>@<host>

SSH Config

Location of SSH settings and host configuration

~/.ssh

If the SSH directory does not exist create it at ~/.ssh

mkdir ~/.ssh
chmod 700 ~/.ssh

If an SSH config file doesn't exist create it at ~/.ssh/config

cd ~/.ssh
touch config
chmod 600 config

Add details for a host entry

Host <nickname>
  HostName <server>
  User <username>
  Port <port>

Use SSH configuration

ssh <nickname>

Add SSH key passphrase to MacOS Keychain

ssh-add -K ~/.ssh/<key-file>

If config file cannot be edited using sudo check the file is not locked in macOS Finder

• File -> Get Info -> General: Locked (Uncheck)

Check the file for the macOS user immutable flag uchg (which disallows editing even by the file owner)

ls -lO ~/.ssh/config

To remove the uchg (user immutable) flag and allow the file to be sudo edited by the owner

chflags nouchg ~/.ssh/config

SSH Access

Connect to remote machine using SSH public / private key instead of username and password.

On the remote machine, if there is no existing ~/.ssh directory or ~/.ssh/authorized_keys file, create one:

mkdir ~/.ssh && cd ~/.ssh
nano authorized_keys

Then past your public key into the file and save.

If an authorized_keys file exists, append your key to that file on a new line.