So say you are behind a typical NAT/LAN setup whether at home, work or while travelling. What if you have a computer or server that you need to connect to from the outside?
Yes you could use a VPN but a quick and dirty, temporary and secure way is to use SSH's Reverse Tunneling Proxy feature.
On the remote ssh server host you need the GatewayPorts option enabled in sshd_config (be sure to restart sshd after making the change)
Your sshd_config needs this:
On the client / machine that is behind the firewall run the SSH command
ssh -R 33000:localhost:3389 username@remoteip
33000 means when we connect to remoteip:33000 we will be connected to port 3389 o the localhost.
Now we can change the localhost to another IP on our LAN if we wanted to.
Now if we connected to remote ip's 3389 we could connect to RDP even though the machine is firewall'd (this works even if all ports are closed and nothing is forwarded to your machine since the ssh -R reverse proxy command is what handles our inbound connections through the remoteip).
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