From: Mart Frauenlob <mart.frauenlob@chello.at>
To: netfilter@vger.kernel.org
Subject: Re: INVALID state
Date: Sun, 28 Feb 2010 11:10:18 +0100 [thread overview]
Message-ID: <4B8A410A.7050003@chello.at> (raw)
In-Reply-To: <4B8A3643.6070000@iit.bme.hu>
On 28.02.2010 10:31, netfilter-owner@vger.kernel.org wrote:
> Dear all
>
> Could someone help me to identify the difference between
> the following 3 rules.
>
> 1. iptables -t mangle -A PREROUTING -p tcp ! --syn -m state --state
> INVALID -j DROP
> 2. iptables -A INPUT -p tcp ! --syn -m state --state INVALID -j DROP
> 3. iptables -A INPUP -p tcp ! --syn -m conntrack --cstate INVALID -j DROP
take a look at this picture, to see, that mangle/PREROUTING may catch
different things than filter/INPUT:
http://jengelh.medozas.de/images/nf-packet-flow.png
Generally filtering (ACCEPT/DROP/REJECT) should be done in the filter
table, unless there is a good reason (and understanding) to do it
otherwise (i.e. the nat table does not allow DROP).
The mangle table is generally meant for packet manipulation. i.e.
marking, changing ip settings, etc...
conntrack supports all states that the state match does, plus some more.
More in general:
imho the '! --syn' is quite unnecessary, correct me if I'm wrong.
Best regards
Mart
next prev parent reply other threads:[~2010-02-28 10:10 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-28 9:24 INVALID state Nemeth Denes
2010-02-28 10:10 ` Mart Frauenlob [this message]
2010-02-28 10:52 ` Nemeth Denes
2010-02-28 11:15 ` Mart Frauenlob
-- strict thread matches above, loose matches on Subject: below --
2008-11-13 18:16 Gilad Benjamini
2008-11-13 22:31 ` Christoph Paasch
2008-11-13 22:34 ` Gilad Benjamini
2008-11-13 23:01 ` Christoph Paasch
2008-11-12 22:08 Gilad Benjamini
2008-11-13 11:13 ` Thomas Jacob
2008-11-13 12:16 ` Christoph Paasch
2008-11-13 12:48 ` Thomas Jacob
2008-11-13 13:08 ` Christoph Paasch
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4B8A410A.7050003@chello.at \
--to=mart.frauenlob@chello.at \
--cc=netfilter@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox