From the responses I'm getting, I don't think I explained the situation
I'm not after "how to write rules" or "what rules should I have". I'm
looking for a generic way to diagram the rules I already have.
Preferably something nice a visual (like Visio), but even Visio starts
to get cumbersome with a complex DMZ, even breaking flows/rules into
layers only goes so far.
I was hoping that the industry had developed some formal standards for
diagramming DMZs and flows/rules.
From: Michael Gale [mailto:michael.gale () bluesuperman com]
Sent: Monday, December 06, 2004 3:26 PM
To: Craig Humphrey; security-basics () securityfocus com
Subject: Re: DMZ / Firewall rule diagramming
Check out some firewall appliances ... most of them
have some sort of
For example I used the following:
Connections from Internal to the DMZ are allowed if they match one of
the forward rules on the firewall.
The forward rules only allow packets from sources addresses to
destination addresses on specific ports which are ruled to be
For connections coming from the DMZ to the internal network which are
required for business (Example. Postfix SMTP server to
forward mail on
to Exchange). The DMZ server connects to a proxy or a NATing rule.
DMZ server never know the IP of a internal server, the DMZ
the same relations with the internal network as the external network
does with the DMZ.
So the DMZ mail server would connect it port 25 on the
firewall and that
traffic would get forwarded to the Exchange server.
That is the standard that I use ... was this what you were
looking for ?