ssh -N -R 2210:localhost:22 [email protected]
This command can be interpreted as, create a tunnel between the remote host's port 2210 and localhost:22, where the remote host is host.com.
-R
implies that the tunnel will be used from the remote side - i.e. host.com.
This command will initiate an ssh connection with reverse port forwarding option which will then open listening port :2210 on host.com who is going to be forwarded back to localhost's port :22 and all this will happen on the remote computer [email protected]
ssh -N -L 2210:node003:22 [email protected]
This command can be interpreted as, create a tunnel between the current host's port 2210 and node003:22 of host.com.
-L
implies that the tunnel will be used from the host that initiated the tunnel.