Re: [Full-Disclosure] A new TCP/IP blind data injection technique?

[Mikael Abrahamsson <swmike@swm.pp.se>]

On Thu, 11 Dec 2003 Valdis.Kletnieks@vt.edu wrote:

> 1) Disable all ICMP, so the ICMP Frag Needed packets don't make it back, thus
> hosing the connection entirely (send too large packet, frag needed, ICMP
> dropped, timeout, retransmit, lather, rinse, repeat).
> 
> 2) Number their point-to-points out of RFC1918 space, so the ICMP Frag Needed
> gets swallowed by some border router that's doing reasonable ingress/egress
> filtering.

Well, actually as far as I have seen the bad thing when pmtud doesnt work 
is often your server farm load sharer that wont forward the icmp message 
to the appropriate server in the farm. 

So a lot of the technology used out there doesnt even by design take ICMP 
NEED TO FRAG-messages into account when they do things. It's not just 
clueless admins, it's clueless designers of equipment.

-- 
Mikael Abrahamsson    email: swmike@swm.pp.se

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