ssh Tunnel(n)

ssh -L 127.0.0.1:AAAA:SERVER:BBBB GATEWAY

oder

ssh -L AAAA:SERVER:BBBB GATEWAY

AAAA=Lokaler Port
SERVER=IP Remote Server
BBBB=Remote Port
GATEWAY=IP Gateway

Tunnel in Tunnel

ssh -p "SSH Port at Machine A" -l "your username at Machine A" -L 127.0.0.1:22222:127.0.0.1:444 "IPD/DNS of Machine A"