[15398] in bugtraq
Re: DoS for web by failing reverse DNS?
daemon@ATHENA.MIT.EDU (Derrick J Brashear)
Tue Jun 20 14:02:25 2000
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Message-Id: <Pine.LNX.3.96L.1000616144509.16789X-100000@jooky.trafford.dementia.org>
Date: Fri, 16 Jun 2000 14:48:13 -0400
Reply-To: Derrick J Brashear <shadow@DEMENTIA.ORG>
From: Derrick J Brashear <shadow@DEMENTIA.ORG>
To: BUGTRAQ@SECURITYFOCUS.COM
In-Reply-To: <Pine.GSO.4.21.0006161925270.25477-100000@madli.ut.ee>
On Fri, 16 Jun 2000, Meelis Roos wrote:
> > A few weeks ago I set up a VPN tunnel and tunneled 16 IP addresses onto a
> > LAN. At the time none of these addresses reverse-resolved to anything.
> >
> > I noticed upon connecting to some web servers that a connection was opened
> > and then hung forever, while others were fine. Some experimentation showed
>
> You may be hit by a Path MTU discovery problem because VPN usually
> decreases maximal available MTU: http://www.worldgate.com/~marcs/mtu/
Further exploration reveals that this is apparently the problem.
Interestingly there were a small number of web servers which were
initially unaccessible which became accessible shortly after the IP
addresses began reverse-resolving to something, but this may also be a
result of a path mtu change; As I can prove nothing in that vein at this
point, I'm content to assume I'm suffering only from the known issue above
rather than that I stumbled upon a new problem.
Thanks for your pointers, all of you.
-D
