From: Chris Brenton <cbrenton@chrisbrenton.org>
To: Christian Seberino <seberino@spawar.navy.mil>
Cc: netfilter <netfilter@lists.netfilter.org>
Subject: Re: TCP packets with RST flag set but **not** ACK flag OK??
Date: Mon, 11 Apr 2005 15:49:21 -0400 [thread overview]
Message-ID: <1113248961.2151.12.camel@grendel> (raw)
In-Reply-To: <1113247121.3544.118.camel@seberino.spawar.navy.mil>
On Mon, 2005-04-11 at 15:18, Christian Seberino wrote:
>
> I think RFC 793 requires TCP stacks to send RSTs if they
> get packets not meant for them in some cases. Anyone know which
> cases?
Pretty much all. The exceptions I can think of off the top of my head:
In response to a RST
In response to a FIN to an open port (MS returns a RST/ACK)
> For example, I think closed ports must send RSTs if they
> get stuff.
Agreed.
> Even if YES, it seems a firewall could drop any RSTs that
> don't have ACK set without damage right?
The only condition I can think of off the top of my head that will
return a RST instead of a RST/ACK is in response to an unsolicited ACK
sent to either an open or closed port. So they do happen in the wild.
HTH,
Chris
next prev parent reply other threads:[~2005-04-11 19:49 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-11 19:18 TCP packets with RST flag set but **not** ACK flag OK?? Christian Seberino
2005-04-11 19:49 ` Chris Brenton [this message]
2005-04-11 21:57 ` Taylor, Grant
2005-04-12 0:36 ` Chris Brenton
2005-04-12 2:32 ` Grant Taylor
2005-04-12 4:06 ` Chris Brenton
2005-04-12 4:01 ` Taylor Grant
2005-04-12 7:24 ` Taylor Grant
2005-04-12 14:41 ` Chris Brenton
2005-04-12 4:22 ` Taylor Grant
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