SSH Port Fordwarding

I saw in this Twitter thread . It is about SSH Port fordwarding which I found interesting and I have needed it a couple of times, so here is a copy and short explanation of it:

If these problems sound familiar:

• A DB server listens on a remote localhost, but you want to use a local GUI client
• A dev service runs on your laptop, but you want to expose it to the Internet

…and you don’t know the solution, read on 👇

🔐 SSH Port Forwarding is the trick.

🔁 There are 3 main types

1. Local Port Forwarding

Tunnel traffic from your local machine to a port on a remote server.

ssh -L local_port:remote_host:remote_port user@ssh_server

🧠 Example: Forward a remote Postgres DB on port 5432 to your localhost:

ssh -L 5432:localhost:5432 user@remote

Now you can connect your GUI client to localhost:5432.

2. Remote Port Forwarding

Expose a local service to a remote server.

ssh -R remote_port:localhost:local_port user@ssh_server

🧠 Example: Make a local Flask app (port 5000) reachable from the remote server:

ssh -R 5000:localhost:5000 user@remote

On the remote server, open http://localhost:5000.

3. Dynamic Port Forwarding (SOCKS Proxy)

Create a SOCKS proxy tunnel through SSH.

ssh -D local_port user@ssh_server

🧠 Configure your browser to use localhost:local_port as a SOCKS5 proxy to route traffic through SSH — like a mini VPN.

🛠️ Tips & Tricks

• Use -N to skip remote command execution:

  ssh -N -L 5432:localhost:5432 user@remote
  

• Add -f to send the command to the background:

  ssh -f -N -L 5432:localhost:5432 user@remote
  

• Combine with -v for verbose debugging if things don’t work:

  ssh -v -L 5432:localhost:5432 user@remote
  

Hope this helps demystify SSH tunnels! 🚀