What is Reverse SSH Port Forwarding
How to Reverse SSH Port Forwarding
In order to SSH into a machine behind a firewall you will need to use Reverse SSH Port Forwarding. The machine in question needs to open an SSH connection to the outside world and include a -R tunnel whose entry point is the remote side (from server in our example) to connect to your machine, allocate a port there and make certain that any connection request on that port is then forwarded to the SSH port of the remote side (server).
From the remote server side run the following command on the server:
ssh –R 2210:localhost:22 username@yourMachine.com
This command will initiate an ssh connection with reverse port forwarding option which will then open listening port 2210: who is going to be forwarded back to localhost’s port :22 and all this will happen on the remote computer username@yourMachine.com.
Read the entire article here, What is Reverse SSH Port Forwarding
via Devolutions, the Remote Desktop Manager guys