how to block ultrasurf traffic on cisco firewall

Unanswered Question
Jul 12th, 2009

i'm using pix firewall and using it as a firewall and as a proxy server, the problem is that i can't block the web access from the clients that installed on their pcs a program named ultrasurf , this program changes the web proxy setting in the internet options of the clients pcs to even if i required from them to use my proxy ip and the port 8080 or 80, that program change these settings to so how please to control that by pix firewall rules, thanks alot for your response and help

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
mchin345 Fri, 07/17/2009 - 05:56

FWSM is a firewall that has a connection based operation. All it sees are connections passing through. It's not possible to look into the payload since UltraSurf encrypts the traffic. Any SSL packet passing through the firewall can be a potential UltraSurf packet. But you can't just block all TCP 443 because many secure connections relay on this protocol.

There is nothing else the FWSM can do to block UltraSurf. Based on Cisco documentation, all it can do to try to block it is the use of ACLs.

In order to have an efficient action over UltraSurf you need advanced encrypted content engines analyzers (like an ACE module that can look into encrypted payload).


This Discussion