SSH Proxy Tunnel

Setup an SSH tunnel proxy server as an intermediary between a local computer and remote server that has an inaccessible resource or service.

Setup

SSH Proxy Tunnel Example

Send the remote service over the SSH port via a tunnel.

Confirm listening ports

Local:

Local host is not listening for any services, so will not return anything.

Porxy

Porxy server running ssh on port 22.

> netstat -ntl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp6       0      0 :::22                   :::*                    LISTEN

Remote

Remote server running web server on port 80 and ssh on port 22.

> netstat -ntl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN
tcp6       0      0 :::22                   :::*                    LISTEN
tcp6       0      0 :::80                   :::*                    LISTEN

From the local server run the following to establish a SSH proxy tunnel:

ssh -N -L localhost:8888:192.168.0.83:80 root@192.168.0.93

• -N is a flag to just forward ports and not execute remote commands
• -L forwards local connections to the remote side
• localhost is the host on the local machine that will bind to the remote service
• 8888 is the port that the local machine will listen on
• 192.168.0.83 is the public IP address of the remote service
• 80 is the port of the remote service
• root is the SSH user of the remote server
• 192.168.0.93 is the public IP address of the proxy server

Local

The SSH tunnel is established for the service at 192.168.0.83:80 will be accessible on the local machine at localhost:8888 via the proxy server at 192.168.0.93.

> netstat -ntl
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 127.0.0.1:8888          0.0.0.0:*               LISTEN
tcp6       0      0 ::1:8888                :::*                    LISTEN

Shorthand

ssh -L 8888:192.168.0.83:80 root@192.168.0.93

Summary

Greate way to access service on local computer that is running on port 80 that is running behind a firewall to access this service from remote computer.

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