ssh -N

https://explainshell.com/explain?cmd=ssh+-N+-f+-L+local_port%3A127.0.0.1%3Aremote_port+user%40host

 Do not execute a remote command.  This is useful for just forwarding ports (protocol version 2 only).

• ssh tunnel

• OpenSSH: ssh, ssh -O, -i, -t, -T, -N, -V, /etc/ssh/ssh_config, ssh --help