From: "René Pfeiffer" <lynx@luchs.at>
To: netfilter@lists.netfilter.org
Subject: Re: ICMP types to allow
Date: Thu, 22 Dec 2005 01:29:05 +0100 [thread overview]
Message-ID: <20051222002905.GI25728@nightfall.luchs.at> (raw)
In-Reply-To: <FAC4E024BF776842876169173CE2F01313B722@mailbox.vikus.com>
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On Dec 21, 2005 at 1336 -0500, Derick Anderson appeared and said:
>
> After reading the ICMP state machine section of the Netfilter tutorial
> [http://iptables-tutorial.frozentux.net/iptables-tutorial.html#ICMPCONNE
> CTIONS] it appears that ICMP traffic related to existing TCP and UDP
> connections falls under the RELATED,ESTABLISHED rules.
This is true. However you need some inbound ICMP in order to support
things like Path MTU discovery. I often allow the inbound ICMP message types
time-exceeded, destination-unreachable and parameter-problem. This
covers messages that deal with packet fragmentation. You might want to
disallow some of the destination-unreachable messages.
Best,
René.
--
)\._.,--....,'``. Let GNU/Linux work for you while you take a nap.
/, _.. \ _\ (`._ ,. R. Pfeiffer <lynx at luchs.at> + http://web.luchs.at/
`._.-(,_..'--(,_..'`-.;.' - System administration + Consulting + Teaching -
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next prev parent reply other threads:[~2005-12-22 0:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-21 18:36 ICMP types to allow Derick Anderson
2005-12-21 18:48 ` John A. Sullivan III
2005-12-22 0:29 ` René Pfeiffer [this message]
2005-12-22 2:08 ` Chris Brenton
2005-12-22 11:03 ` René Pfeiffer
2005-12-22 8:50 ` lst_hoe01
-- strict thread matches above, loose matches on Subject: below --
2005-12-21 19:12 Derick Anderson
2005-12-21 16:31 Peter E. Fry
2005-12-21 13:45 Derick Anderson
2005-12-21 14:16 ` lst_hoe01
2005-12-21 16:27 ` Georgi Alexandrov
2005-12-21 19:22 ` Cedric Blancher
2005-12-21 22:01 ` Chris Brenton
2005-12-22 0:32 ` René Pfeiffer
2006-01-03 7:33 ` Jan Engelhardt
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