Beating a Firewall

[bruder]

We are making a small firewall type utility for our internal company and as part of my task I have to find out all vulnerabilities in Firewalls. So tell me, how do I get around a firewall that has most non-common ports blocked (open ports are the normal, 1-1024).

[Jordan]

To get around a firewall is fairly simple and I'm not sure if there is anyway to block it. A proxy server on Port 80, 22, 21 or any of your standard ports will allow someone to get out (these are freely available on the internet). Another way is to do SSH port Forwarding which basically simulates a Socks 5 proxy server once you have logged in.

Hope that helps.

[Kaabi]

I know there are firewalls out there that can't be penetrated, at least not by incredibly expert hackers.

[TcM]

Can you state some? Are they software or hardware?

[lasthell]

There is not a single firewall which can not be penetrated. The basic reason behind this is firewall only looks for ports and does not decode the protocol of the data flowing through that port. You can just make your firewall stronger not 100% penetration-proof.. First instead of blacklist of ports to be blocked, maintain the white list of ports to be allowed. You can embed NBA(Network behavior analysis) module to make firewall take more intelligent actions.
You need to use advanced IDS systems to decode application level protocols to take care of shortcomings.