How to create an SSH SOCKS proxy

SOCKS proxy is a Layer 5 proxy that allow secure routing or tunneling of any type of programs or protocols. You could create a SOCKS proxy to tunnel network traffic between your local and a remote host and then route your applications through the proxy.

You could use it to securely access the internet in a public network such as in a public WiFi environment as the traffic between your host and the proxy server is encrypted. It could also be used to access hosts behind a private network under a NAT or firewall just as a VPN would.

You need to have SSH access to a remote server and to create a SOCKS proxy using SSH client from Linux or any other Unix-based operating systems to the server at the terminal.

1. Launch a terminal application.
2. Test your connection to the remote host (optional).

   $ ssh user@remote-host hostname
   remote-host

3. Connect to the remote host using bind_address option to create an SSH SOCKS proxy from your local machine to the remote SSH server.

   $ ssh -D8080 user@remote-host
   The authenticity of host 'remote-host (10.1.1.100)' can't be established.
   ECDSA key fingerprint is SHA256:wGCE8M54I94AgSatEcB9Y26CxmDjb9YtlL0HMpSiIRA.
   Are you sure you want to continue connecting (yes/no)? yes
   ##### snipped 

   -D [bind_address:]port
           Specifies a local “dynamic” application-level port 
           forwarding.  This works by allocating a socket to 
           listen to port on the local side, optionally bound 
           to the specified bind_address.  Whenever a connection 
           is made to this port, the connection is forwarded 
           over the secure channel, and the application protocol 
           is then used to determine where to connect to from 
           the remote machine.  Currently the SOCKS4 and SOCKS5 
           protocols are supported, and ssh will act as a SOCKS 
           server. Only root can forward privileged ports.  
           Dynamic port forwardings can also be specified in 
           the configuration file.

   8080 in the example is the port that your SOCKS proxy will listen to. You can choose any number from 1025 to 65535 if you're running the command as a normal user, as long as the port number is not currently in use.

   Common options to run SOCKS proxy in the background::

    ssh -D8080 -fCqN  user@remote-host

   • -f: Requests ssh to go to background just before command execution
   • -C: Requests compression of all data
   • -q: Quiet mode. Causes most warning and diagnostic messages to be suppressed
   • -N: Do not execute a remote command

   Related: How to allow public access to SSH tunnel

4. Check if the tunnel is running in your local host.

   $ ss -natp | grep 8080
   LISTEN  0        128               127.0.0.1:8080               0.0.0.0:*        users:(("ssh",pid=1640,fd=6))
   LISTEN  0        128                   [::1]:8080                  [::]:*        users:(("ssh",pid=1640,fd=5))

5. Connect program to your SOCKS proxy to test if the tunnel is successful.

   $ curl ifconfig.me # Direct connection
   95.136.221.23
   $ curl -x socks5h://127.0.0.1:8080 ifconfig.me # Via socks proxy tunnel
   84.139.115.17

6. Configure your browser or any other applications to connect through you newly created SOCKS tunnel.