[nsp] ipv6 address ::X/128 on Cisco router

[Tantsura, Jeff]

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Gert Doering
Sent: Saturday, June 19, 2004 12:08 AM
To: Stephen J. Wilcox
Cc: Ryan O'Connell; Gert Doering; cisco-nsp at puck.nether.net
Subject: Re: [nsp] ipv6 address ::X/128 on Cisco router

Hi,

On Fri, Jun 18, 2004 at 09:48:49PM +0100, Stephen J. Wilcox wrote:
> i thought (and cant find a link to confirm this so i may be wrong..)
> that 127/8 is implicitly dropped on ingress as it is not a valid
address for a router?

The hosts requirements RFC requires that packets with such a source or
destination address never appears on the wire.

Recent worms have demonstrated that Microsoft programmers don't know
this
- Windows worms have been seen sending out packets with a source IP of
127.0.0.1 (source port 80) to random destinations, and both C and J
routers happily forward them, unless uRPF (or similar) is applied.

Right, I've seen 1000000's of these on UNIX's firewalls.

Jeff




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