* Re: ECN: Clearing the air
[not found] <Pine.GSO.4.30.0101271809070.24762-100000@shell.cyberus.ca>
@ 2001-01-28 0:23 ` jamal
2001-01-28 2:08 ` Chris Wedgwood
0 siblings, 1 reply; 6+ messages in thread
From: jamal @ 2001-01-28 0:23 UTC (permalink / raw)
To: linux-kernel; +Cc: netdev
On Sat, 27 Jan 2001, jamal wrote:
>
> - ECN does not break things. It's brain damaged firewalls, Intrusion
> detection systems, and load balancers that should be shot.
> One intrusion detection "expert" was quoted suggesting the blocking of ECN
> bits should be blocked because "nmap uses them" to probe systems.
>
should proof read before posting. The intrusion detection expert
suggested blocking ECN. Article at:
http://www.securityfocus.com/frames/?focus=ids&content=/focus/ids/articles
/portscan.html
cheers,
jamal
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: ECN: Clearing the air
2001-01-28 0:23 ` ECN: Clearing the air jamal
@ 2001-01-28 2:08 ` Chris Wedgwood
2001-01-28 2:15 ` jamal
0 siblings, 1 reply; 6+ messages in thread
From: Chris Wedgwood @ 2001-01-28 2:08 UTC (permalink / raw)
To: jamal; +Cc: linux-kernel, netdev
On Sat, Jan 27, 2001 at 07:23:51PM -0500, jamal wrote:
suggested blocking ECN. Article at:
http://www.securityfocus.com/frames/?focus=ids&content=/focus/ids/articles/portscan.html
the site is now ATM -- can someone briefly explain the logic in
blocking it?
--cw
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: ECN: Clearing the air
2001-01-28 2:08 ` Chris Wedgwood
@ 2001-01-28 2:15 ` jamal
2001-01-28 21:55 ` Pavel Machek
0 siblings, 1 reply; 6+ messages in thread
From: jamal @ 2001-01-28 2:15 UTC (permalink / raw)
To: Chris Wedgwood; +Cc: linux-kernel, netdev
On Sun, 28 Jan 2001, Chris Wedgwood wrote:
> On Sat, Jan 27, 2001 at 07:23:51PM -0500, jamal wrote:
>
> suggested blocking ECN. Article at:
>
> http://www.securityfocus.com/frames/?focus=ids&content=/focus/ids/articles/portscan.html
>
> the site is now ATM -- can someone briefly explain the logic in
> blocking it?
>
It is Queso they quoted not nmap, sorry -- same thing.
The idea is to "detect" port scanners.
Queso sets the two TCP reserved bits in the SYN (now allocated for ECN).
Some OSes reflect that back in the SYN-ACK (Linux < 2.0.2? for example
was such a culprit).
Queso could then use that information to narow down the OS detection.
I suppose the idea is to detect Queso and react to it ;->
cheers,
jamal
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: ECN: Clearing the air
2001-01-28 2:15 ` jamal
@ 2001-01-28 21:55 ` Pavel Machek
2001-01-29 16:21 ` Walter Hofmann
2001-01-30 2:11 ` jamal
0 siblings, 2 replies; 6+ messages in thread
From: Pavel Machek @ 2001-01-28 21:55 UTC (permalink / raw)
To: jamal, Chris Wedgwood; +Cc: linux-kernel, netdev
Hi!
> > suggested blocking ECN. Article at:
> >
> > http://www.securityfocus.com/frames/?focus=ids&content=/focus/ids/articles/portscan.html
> >
> > the site is now ATM -- can someone briefly explain the logic in
> > blocking it?
>
> It is Queso they quoted not nmap, sorry -- same thing.
> The idea is to "detect" port scanners.
> Queso sets the two TCP reserved bits in the SYN (now allocated for ECN).
> Some OSes reflect that back in the SYN-ACK (Linux < 2.0.2? for example
> was such a culprit).
Does not that mean that Linux 2.0.10 mistakenly announces it is ECN
capable when offered ECN connection?
Pavel
--
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: ECN: Clearing the air
2001-01-28 21:55 ` Pavel Machek
@ 2001-01-29 16:21 ` Walter Hofmann
2001-01-30 2:11 ` jamal
1 sibling, 0 replies; 6+ messages in thread
From: Walter Hofmann @ 2001-01-29 16:21 UTC (permalink / raw)
To: Pavel Machek; +Cc: jamal, Chris Wedgwood, linux-kernel, netdev
On Sun, 28 Jan 2001, Pavel Machek wrote:
> Does not that mean that Linux 2.0.10 mistakenly announces it is ECN
> capable when offered ECN connection?
No, the RFC deals with this.
Walter
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: ECN: Clearing the air
2001-01-28 21:55 ` Pavel Machek
2001-01-29 16:21 ` Walter Hofmann
@ 2001-01-30 2:11 ` jamal
1 sibling, 0 replies; 6+ messages in thread
From: jamal @ 2001-01-30 2:11 UTC (permalink / raw)
To: Pavel Machek; +Cc: Chris Wedgwood, linux-kernel, netdev
On Sun, 28 Jan 2001, Pavel Machek wrote:
>
> Does not that mean that Linux 2.0.10 mistakenly announces it is ECN
> capable when offered ECN connection?
In fact it does. But as someone mentioned, ECN is resilient to this.
i.e this will be trapped and no ECN connection will happen.
For historical purposes, let it be noted that it was the Linux
ECN implementation in the 2.0 days that made this change in the RFC
possible. "we believe in running code ..." -- yes, indeed.
cheers,
jamal
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^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2001-01-30 2:12 UTC | newest]
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[not found] <Pine.GSO.4.30.0101271809070.24762-100000@shell.cyberus.ca>
2001-01-28 0:23 ` ECN: Clearing the air jamal
2001-01-28 2:08 ` Chris Wedgwood
2001-01-28 2:15 ` jamal
2001-01-28 21:55 ` Pavel Machek
2001-01-29 16:21 ` Walter Hofmann
2001-01-30 2:11 ` jamal
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