Snort mailing list archives

RE: Nmap


From: "Marc Quibell" <mquibell () fbfs com>
Date: Thu, 20 Nov 2003 09:19:36 -0600




Er..maybe the webserver communicates with other servers on another port? Like
directory services...etc? I suppose it depends on where the firewall is, and
where ther other internal servers are..etc.
I dunno, but I have this nagging feeling that source-port filtering really
doesn't accomplish much. I mean, today's attacks occur on the public ports, such
as port 80, 443, 21...etc. What you're doing is introducing outbound header
inspection, just to avoid the server responding from any other port besides 80.
What is the purpose of this anyways?

Cheese,

Marc



--__--__--

Message: 4
Subject: RE: [Snort-users] Nmap
Date: Wed, 19 Nov 2003 12:02:31 -0600
From: <bmcdowell () coxhealthplans com>
To: <snort-users () lists sourceforge net>


You know what, I just realized that I do do some filtering based on the =
source port:  outbound filtering.  E.g.

iptables -A FORWARD -s [webserver] --sport ! 80 -j DROP

There isn't anything wrong with doing that, is there?


Bob




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