[e2e] ICMP & TCP segments with IP ID = 0?
Tushar Saxena
tsaxena at bbn.com
Wed May 16 10:29:46 PDT 2001
It seems like linux 2.4 doesn't worry about the ID field
if DF is set. There was some discussion on DF/ID on
tcp-impl some time back. Here's the link:
http://tcp-impl.lerc.nasa.gov/tcp-impl/list/archive/2378.html
Also, looking at some traces on the web, it seems like some
implementations of BOOTP/DHCP may also be leaving ID
undefined in the ip packet containing the bootp-udp
datagram. I looked at ipconfig.c in the linux kernel,
in function ic_bootp_send_if(), and it also seems to
turn on IP_DF in the iphdr, and set all the iphdr fields,
but leave the ID undefined (probably 0).
Tushar
Craig Partridge wrote:
>
> Hi folks:
>
> 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.
>
> Thanks!
>
> Craig
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