Re: Traceroute Mal-formed packets

From: Casey Carter (
Date: Thu Mar 06 2003 - 09:39:06 EST

John McLaren wrote:

>I stand corrected.. i should have said "udp length" rather than header length.
>I was under the impression that this had to be multiples of long words also.
You can even send a 0 byte UDP packet if you want, so any length >= 8
(the header size) is valid.

>Nonetheless... what is the need for any data in this packet? Traceroute
>uses incrementing to assure that the return packets can be effectively
>ID'd, right?
traceroute is a testing tool. Since you might want to determine where
packets to host X of size greater than Y bytes are being dropped, adding
data bytes is useful.

>If nothing else, this anomoly might be useful in identifying certain router
>types that consider this to be a mal-formed packet.
I think it's very likely that Cisco can build RFC791-compliant routers.
 The most likely source of problems here is the NAT setup.

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Casey Carter
AIM: cartec69

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