-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi everyone,
I have a question regarding stateful inspection firewalls (specifically pix and checkpoint). It seems to me that a lot of people use either nat or pat and that these types of firewalls by default drop unsolicited connection attempts (meaning packets that arrive with the syn bit set). Any packet that leaves the network is put in the state table so that the return packets can come back in. My question is this; if I were to exploit a client-side buffer overflow and I got the system to make a connection to me via netcat with a destination port of 80, would I circumvent a majority of the stateful inspection firewalls? It seems that these firewalls trust that ALL connections originating from the inside are good. Now I know we could block off destination ports of services we don't want to allow access to (say no port 23 traffic leaves the network because we don't allow telnet) but I am wondering if either of these firewalls have a method of filtering based on protocol (for example allow 80 to be a destination port but only http traffic can cross it. No netcat, no aim, no limewire just http. I have seen a ton of networks where I came in and I found people using things like aim even though the firewall specifically only permitted port 80 traffic out (obviously these people switched the port from 5190 to 80). So to reiterate; is there a way to configure pix or checkpoint to judge the connection based on protocol as opposed to arbitrary things like source ip, destination IP or port numbers? Cheers and thanks in advance, PS: Links are appreciated but flames are not :) Leon -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 6.5.8 for non-commercial use <http://www.pgp.com> iQA/AwUBPGHkRtqAgf0xoaEuEQJgUgCgiGaVcoapw7+T4+QYqADv/jJYIycAni9v W0GcE8qAvdNF6ZNanoDjjyn3 =u/Nk -----END PGP SIGNATURE-----
