SSH through HTTP Proxies

A couple of days ago my office implemented a new firewall which block almost all incoming and outgoing traffic, including SSH which prevented me from accessing my Linux server. The only thing that was accessible was the internet through a HTTP proxy which implemented filtering capabilties and required credentials. Fortunately, with this I’m able to create a tunnel and encapulate a SSH connection into HTTP.

To create a HTTP tunnel I chose to use the GNU HTTP Tunnel software which does the work to encapsulate TCP into HTTP requests. For the Windows platform a binary version is also available

Setting up the tunnel

On the home computer (server):

Install the GNU HTTP Tunnel with the following command:

$ apt-get install httptunnel

Start the HTTP Tunnel server:

$ hts --forward-port localhost:22 8080

Here the HTTP Tunnel server receives HTTP requests through port 8080, decapsulates and re-assembles the ssh stream and forwards it to port 22, the SSH server.

On the office computer (client):

Start the HTTP Tunnel client:

$ htc --forward-port 900 --proxy OfficeProxy:8080 HomeComputer:8080

Here the HTTP Tunnel client listens on port 900 for a ssh stream, as well it establishes a TCP connection which can pass data back and forth to the home computer through the HTTP proxy.

If the proxy requires authentication, add --proxy-authorization username:password to the htc command line.

Finally to establish a SSH connection run the following:

$ ssh username@localhost:900

For information: Punching holes into firewalls

Related posts:

1. HTTP Tunnel Through ISA Server
2. Surfing the Web using SSH Tunnel
3. Installing BoutDuTunnel Server on Mono XSP
4. Remote Desktop with SSH Tunneling
5. SSH Authentication with public-key