From: Simon Kirby <sim@netnation.com>
To: Pablo Neira <pablo@eurodev.net>
Cc: netfilter-devel@lists.netfilter.org
Subject: Re: REJECT using invalid data
Date: Tue, 7 Dec 2004 09:28:23 -0800 [thread overview]
Message-ID: <20041207172823.GA31513@netnation.com> (raw)
In-Reply-To: <41B58EE3.5050709@eurodev.net>
On Tue, Dec 07, 2004 at 12:07:15PM +0100, Pablo Neira wrote:
> not really, my ruleset drops it, actually another rule here is
> previously logging it.
>
> -A INPUT -m state --state INVALID -j DROP
That's all fine and dandy, except that we can't use state tracking in our
configuration because of asymmetric routing (which is required due to
BGP). This is fairly common, and not an incorrect setup.
> > REJECT can be set to reject with a
> >tcp-reset or some ICMP response at this point. If so, it will actually
> >use the possibly-incorrect information from the bad TCP packet and send a
> >rejection packet. As far as I can tell, this is a bug.
>
> yes, that's a bug, but in your ruleset, people should log/drop/let
No! It is not a bug in our ruleset, it is a bug in REJECT.
It is incorrect to reply to packet layers that have bad checksums.
REJECT in this case must DROP, because anything else would be broken.
Simon-
next prev parent reply other threads:[~2004-12-07 17:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-07 1:01 REJECT using invalid data Simon Kirby
2004-12-07 11:07 ` Pablo Neira
2004-12-07 17:28 ` Simon Kirby [this message]
2004-12-07 22:14 ` Pablo Neira
2004-12-08 2:47 ` Kiran Kumar Immidi
[not found] <Pine.LNX.4.53.0412072347080.2736@bizon.gios.gov.pl>
2004-12-07 23:54 ` Pablo Neira
2004-12-08 0:33 ` Krzysztof Oledzki
2004-12-08 0:52 ` Simon Kirby
[not found] ` <Pine.LNX.4.53.0412101310210.1288@bizon.gios.gov.pl>
2004-12-10 13:10 ` Simon Kirby
[not found] ` <Pine.LNX.4.53.0412101439530.6072@bizon.gios.gov.pl>
2004-12-10 14:49 ` Simon Kirby
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