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Message-ID: <Pine.LNX.4.50.0508301703200.7900-100000@kegger.national-security.net>
Date: Wed Aug 31 01:38:43 2005
From: fd at ew.nsci.us (fd@...nsci.us)
Subject: RE: Example firewall script
On Tue, 30 Aug 2005, Rachael Treu Gomes wrote:
> > There are also issues of what KIND of ACL to
> > use and where to place them; Inbound or Outbound.
> >
> > In terms of the original question, the only
> > difference between a "good" line item or a
> > "bad" line item is whether or not the syntax
> > is correct.
>
> Nicely put.
> >
> > The only difference between a "good" ACL
> > and a "bad" ACL is whether or not it's
> > structure is properly designed and whether
> > or not it's placed in the proper location.
>
> Again, nicely put. I might also suggest adding the
> idea that ACL logic and format follow with the same
> requirements for placement, and that overarching
> rules/guidelines regarding their structure and flow be
> evaluated on a case-by-case basis. It is incomplete
> and rife with exception, unfortunately, to decree that
> all ACLs and firewall feature sets be constructed in a
> particular manner without taking into account the
> particulars surrounding their respective deployments.
Can anyone suggest a book which discusses ACL theories in different points
of view and practical (?existing) applications? I would love to see
documentation which addresses security and manageability as it relating to
things like minimal ACL-line duplication and ingress+egress filtering
techniques. Even in Cisco and 5xx-level networking courses, these issues
are barely touched on. For traffic policies, much has been learned from
this list and from practical experience.
-Eric
--
Eric Wheeler
Vice President
National Security Concepts, Inc.
PO Box 3567
Tualatin, OR 97062
http://www.nsci.us/
Voice: (503) 293-7656
Fax: (503) 885-0770
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