Shyamal Vaderia

Mapping Knowledge

1 minute read

This guide provides instructions on how to access services on remote servers that can only be reached via a proxy, using nc (netcat) and socat on an Ubuntu server.

Setting Up the Proxy Tunnel

First, establish an SSH SOCKS proxy tunnel. This tunnel will allow traffic to pass from your local system through the proxy:

ssh -D 8123 -C -q -N [Your SSH User and Host]

This command creates a SOCKS proxy on port 8123 of your local machine.

Configuring socat Tunnel

Next, set up a socat tunnel to listen on a local port and forward traffic through the SOCKS proxy:

socat TCP-LISTEN:localport,fork SOCKS4A:localhost:target-server.com:targetport,socksport=8123
  • Replace localport with a local port number of your choice where socat will listen.
  • target-server.com should be replaced with the address of the server you’re trying to access.
  • targetport is the port number of the service on the target server.

Connecting with nc

Finally, use nc to connect to the local port where socat is listening:

nc localhost localport

This setup enables your nc traffic to route through the SOCKS proxy, allowing access to services on the remote server that require proxy access.

By following these steps, you should be able to access remote services through the SSH SOCKS proxy using nc and socat. Ensure to replace placeholders like localport, target-server.com, and targetport with actual values relevant to your use case.