Snort mailing list archives

Re: how to block P2P with snort


From: Sylvain BERTRAND <sbertran () metz supelec fr>
Date: Thu, 01 Apr 2004 13:22:56 +0200

http://sourceforge.net/projects/iptables-p2p/ is excellent, no need to look further... even if l7-filter looks amazing The P2P match for iptables can detect most of the P2P protos around, except a few (Soulseek, maybe others...).
This and the classic portblocking rules should be enough.

Sylvain

PS: I know this was not "snort related", but I tought it my help some of us


Ravi wrote:

Sylvain,
Blocking P2P traffic is difficult job for snort.
   - Some P2P applications uses TCP, if not switches to UDP
- Even some applications started using encryption to communicate,and snort cant intrepret encrytped packets. But signatures can be written to block the traffic before encryption takes place. Hmm, giving a chance to lot of false positives.
  I think anamoly detection can help to block p2p.

There are some open source tools some working with iptables to block p2p.
YOu may would like to look into this tools:
   - http://l7-filter.sourceforge.net/
  - http://sourceforge.net/projects/iptables-p2p/
You can also block using squid as transparent proxy. Configure the ACL and it will work fine if the p2p uses http protocol. I have not used them yet, so let me know which is best in action.

Cheers,
-Ravi
ROCSYS Technologies Ltd.,
http://www.rocsys.com





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