From: Peter Surda <surda@shurdix.com>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] Interesting article about punching holes in firewalls...
Date: Thu, 21 Dec 2006 07:10:51 +0000 [thread overview]
Message-ID: <458A337B.1060400@shurdix.com> (raw)
In-Reply-To: <45860240.2040102@riverviewtech.net>
Grant Taylor schrieb:
> I personally have known that using "-m state --state
> ESTABLISHED,RELATED" was not the most secure thing to use for returning
> traffic.
Actually, what the described method accomplishes is not defeating the
"firewall" part, but the "NAT" part. If one of the hosts was not behind
a NAT, the traffic would flow even with ESTABLISHED,RELATED, because it
belongs to active "connection".
> Namely this will allow you to make a valid connection to a web
> server, say to retrieve a picture. Then said web server could send
> malicious traffic back to your computer and pass through your firewall.
Please note it does not allow you to create a new connection, just use
POTENTIAL connections that wouldn't work due to NAT.
> Grant. . . .
Yours sincerely,
Peter
--
http://www.shurdix.org - Linux distribution for routers and firewalls
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next prev parent reply other threads:[~2006-12-21 7:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-18 2:51 [LARTC] Interesting article about punching holes in firewalls Grant Taylor
2006-12-20 21:23 ` Stephen Hemminger
2006-12-21 7:10 ` Peter Surda [this message]
2006-12-21 7:57 ` Carl-Daniel Hailfinger
2006-12-21 15:37 ` Grant Taylor
2006-12-21 15:55 ` /dev/rob0
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