SSH Tunnel

• Dynamic Port Forwarding: listening on ssh client, forwarding from ssh server, target host:port is determined by SOCKS4/SOCKS5

      # -f is running in background, optinal
      # -v is printing debugging messages
      ssh -ND [bind_address:]port johnson@jserver
  
      # example: set up a SOCKS5 proxy at localhost
      ssh -vND 1080 johnson@jserver
      

• Local Port Forwarding: listening on ssh client, forwarding from ssh server

      # -f is running in background, optinal
      # -v is printing debugging messages
      ssh -NL [bind_address:]port:host:hostport] johnson@jserver
      

• Remote Port Forwarding: listening on ssh server, forwarding from ssh client

      # -f is running in background, optinal
      # -v is printing debugging messages
      ssh -NR [bind_address:]port:host:hostport] johnson@jserver
  
      # example: remote SSH access local server which is inside a firewall
      # 1. exec on the local server, port 10000 will listen on remote server, 22 is the local server ssh port
      ssh -vNR 10000:localhost:22 remote_server_user@jserver
      # 2. exec on the remove server
      ssh -p10000 lan_server_user@localhost