Accessing a Private Server via SSH Tunneling

Create an SSH Tunnel from Your Machine

To access a private server (private-server) inside a remote network, establish an SSH tunnel through a publicly accessible server (gateway-server).

ssh -L 2222:192.168.1.100:22 user@gateway-server

ssh -L 2222:192.168.1.100:22 user@gateway-server

• -L 2222:192.168.1.100:22 → Forwards local port 2222 to private-server:22.
• user@gateway-server → The intermediate server with public access.

Open a New Terminal and Connect to the Private Server

ssh -p 2222 user@localhost

ssh -p 2222 user@localhost

Now, you're securely connected to private-server!

Run the Tunnel in the Background

To keep the tunnel running in the background, use:

ssh -f -N -L 2222:192.168.1.100:22 user@gateway-server

ssh -f -N -L 2222:192.168.1.100:22 user@gateway-server

• -f → Run in background.
• -N → Do not execute remote commands, only forward ports.

Automate the Tunnel with SSH Config

Add the following to ~/.ssh/config on your local machine for quick access:

Host private-tunnel
    HostName gateway-server
    LocalForward 2222 192.168.1.100:22

Host private-tunnel
    HostName gateway-server
    LocalForward 2222 192.168.1.100:22

Now, simply run:

ssh private-tunnel
ssh -p 2222 user@localhost

ssh private-tunnel
ssh -p 2222 user@localhost

This setup allows seamless access to a private server behind a firewall using SSH tunneling!