SSH Tunnelling

SSH Tunneling

Local Port Forwarding

Local port forwarding allows you to forward a port from your local machine to a remote server. This is useful for accessing services on a remote network.

ssh -L [local_port]:[remote_address]:[remote_port] user@remote_host -p [ssh_port]

Example:

ssh -L 8080:192.168.1.20:3389 user@remote_host -p 2222

Access the service via localhost:8080.

Dynamic Port Forwarding

Dynamic port forwarding creates a SOCKS proxy on your local machine, which can be used to route traffic through the SSH server.

ssh -D [local_port] user@remote_host -p [ssh_port]

Example:

ssh -D 8181 user@remote_host -p 2222

Configure your applications to use localhost:8181 as a SOCKS proxy.

Reverse Tunneling

Reverse tunneling allows a remote server to access services on your local machine.

ssh -R [remote_port]:localhost:[local_port] user@remote_host -p [ssh_port]

Examples:

1. Forward RDP:

   ssh -R 8181:localhost:3389 user@remote_host
   

2. Forward SSH:

   ssh -R 43022:localhost:22 user@remote_host -p 45
   

   Connect using:

   ssh localhost -p 43022
   

Note: Ensure GatewayPorts and AllowTcpForwarding are enabled on the server.

Serve Local Service as Remote Service

This setup allows you to expose a local service to a remote server, making it accessible from the remote network.

You are essentially binding a port from your local system to the remote port. You could host your website locally and share that port via the SSH service, making the port available on your remote system without actually port-forwarding.

ssh -N -R [remote_port]:127.0.0.1:[local_port] user@remote_host -p [ssh_port]

Example:

Forward a local service on port 8096 to a remote server:

ssh -N -R 8096:127.0.0.1:8096 user@$KALI -p 4444

Configuration: Ensure GatewayPorts yes is set in /etc/ssh/sshd_config on the remote server to allow remote hosts to connect to the forwarded port.

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Minecraft Server Example

Here’s an example if you wanted to share your local Minecraft server to a remote host:

ssh -vvv -N -R 25565:127.0.0.1:25565 [email protected]

• -vvv: Enables verbose mode for detailed debugging information.
• -N: Tells SSH not to execute a remote command, useful for port forwarding only.
• -R: Specifies reverse port forwarding.

Now on the remote system/hosting provider, you can check the port 25565 and you’ll see that it’s bound to your local machine via a SSH Tunnel.

VNC Forwarding

Forward VNC traffic through SSH:

ssh -L [local_port]:localhost:[vnc_port] user@remote_host

Example:

ssh -L 5903:localhost:5900 [email protected]

X11 Forwarding

X11 forwarding allows you to run graphical applications over SSH.

ssh -X user@remote_host

For a fully trusted connection, use:

ssh -Y user@remote_host

Set up the display:

xhost +
export DISPLAY="127.0.0.1:10.0"

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