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From: Chris Brenton <cbrenton@chrisbrenton.org>
To: netfilter <netfilter@lists.netfilter.org>
Subject: Re: blocking by domain
Date: Sun, 13 Jun 2004 07:26:37 -0400	[thread overview]
Message-ID: <1087125996.2011.6.camel@grendel> (raw)
In-Reply-To: <1087115340.1891.2.camel@anduril.intranet.cartel-securite.net>

On Sun, 2004-06-13 at 04:29, Cedric Blancher wrote:
>
> Moreover, I
> think it would generate too much latency if you had to check DNS for
> packets at firewall level.

Not to mention the accuracy is pretty poor. Say I'm fubar.com and you
have a rule blocking traffic from my domain. I can either:

1) Not create a PTR record for my IP
2) Create a PTR calling myself www.microsoft.com or similar

Both methods will defeat a domain based filter. So blocking at an IP
level is faster and more accurate. Best bet is to just do a few whois
queries to identify the IP range for the domain and block accordingly. 

HTH,
Chris




      reply	other threads:[~2004-06-13 11:26 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-06-12 21:27 blocking by domain Spiro Azkoul
2004-06-13  8:29 ` Cedric Blancher
2004-06-13 11:26   ` Chris Brenton [this message]

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