re-using SSH connections

The ssh ControlMaster setting “allows you to re-use an existing SSH connection whenever you connect to a host you are already connected to.”

In your ~/.ssh/config file, add:

Host *
    ControlMaster auto
    ControlPath /tmp/%r@%h:%p

Whenever you connect to server.example.com as user joeuser, SSH will create a named pipe at /tmp/joeuser@server.example.com:22. If you open another connection to the same server (as the same user), instead of creating a new TCP/IP connection, SSH will automatically multiplex the new session with the existing connection (through the named pipe)! This reduces time spent setting up new connections.