[e2e] ICMP & TCP segments with IP ID = 0?

[kuznet at ms2.inr.ac.ru]

Hello!

> As a side discovery on a research project, we've tripped over a bunch of
> packets in the wild where the IP ID is set to 0.  Some are ICMP packets
> and some are TCP segments.
> 
> Before we set up a traffic filter to track down what brand of system is
> generating these evil beasts, I'm writing to see if anyone has already
> figured out what kind of system sends them.

Linux-2.3 set ip id to 0 on packets with DF, because it is undefined there.
Do you really think it is illegal? 8)

Alexey