Break Your Firewall And Proxy Rules

Break your Firewall And Proxy Rules

Written By akash b
mar 5 20049

This tutorial will explain

1). How to use Yahoo Messenger blocked by firewall or proxy.
2). How to use MSN Messenger blocked by firewall or proxy.
3). How to use IRC blocked by firewall or proxy.
4). How to use FTP blocked by firewall or proxy.
5). How to use ICQ blocked by firewall or proxy.
6). How to use Telnet blocked by firewall or proxy.
7). How to use P2P software like Kazza, Edonkey blocked by firewall or proxy.
8). Other applications which cannot use proxy.

Most of the companies allow only website surfing (i.e. port 80), but they restrict all other ports so the employees cannot accesses Messengers P2P ftp server etc. But there are some ways out for breaking these rules set at your firewall or proxy server. One of the ways is to use HTTP Tunneling technique.

What is HTTP TUNNELING?

“Tunneling” sounds good. The method which we are going to use is almost similar to the literal meaning of Tunneling.

Normal scenario
Take an example using an FTP service.
When you connect to an FTP site using an FTP client packet request will be as below

Source IP : your IP address
Source Port : your computer port
Destination IP : 205.*.*.1 (ftp server you are trying to connect)
Destination Port : 21
DATA : Get file File.zip

Let us think there is a firewall in your network. Administrator of your network might have blocked port 21 (normally all outing ports are blocked other than port 80). So now you cannot accesses FTP server 205.*.*.1.Think if this is the scenario is there any way to bypass your firewall rule?

Yes you can do it.
Why can’t we put up a middleman which can accept all your port 80 request and translate it to port 21 request then send it to your FTP server i.e. 205.*.*.1. Now you are asking the middleman server which you have installed outside the company to connect to FTP server 205.*.*.1 on port 21 and get the file you required, send it back it to you. This is HTTP Tunneling.

Now the packet you are sending will be like below

Source IP : your IP address
Source Port : your computer port
Destination IP : Middleman Server IP
Destination Port : 80
DATA : Connect to 205.*.*.1 using port 21 and get file File.zip and send it to your IP

If the firewall captures this packet it will think that it is a port 80 request for the middleman server. So it is a genuine request and it will allow it to pass through.

So for doing it you need a two components one client and a server module. Install client module inside your company. Install server module (middleman) outside company it can be your personal PC at your home. Configure your softwares i.e. your Yahoo messenger or IRC to communicate to your client software installed. Client software will convert your request in HTTP format and send it to middleman server. Middleman server i.e. your home PC is basically a web server with a twist. When client is doing tunneling, it sends series of HTTP requests to the server. Your company firewall sees as if you were surfing to some web site, and consciously allows you. Server module i.e. your PC in turn performs it's half of tunneling and talks to the target servers.

I am attaching a figure with this Tutorial.

You can get the tunneling software from links below

http://www.http-tunnel.com
http://www.htthost.com/
http://www.nocrew.org/software/httptunnel.html
http://www.codeguru.com/Cpp/I-N/internet/h...icle.php/c6209/
http://www.totalrc.net/s2h/index.jsp

This is the modified version of my previous post