dhclient doing DISCOVER with bad IP checksum - bge (7.1 show stopper??)

Jonathan Feally vulture at netvulture.com
Tue Dec 2 11:09:04 PST 2008


Jonathan Feally wrote:
> I will try another em card in that server to confirm/rule out the nic 
> driver. I am seeing the same checksum number on both the source 
> machine, the dhcp server machine, and a 3rd windows xp machine 
> sniffing the traffic with etherreal/wireshark. The windows xp box is 
> running an intel nic as well, and those 0.0.0.0.67 -> 
> 255.255.255.255.68 packets as seen by the server do have the correct 
> checksum. After the nic test, if no change from one driver to the 
> other, then I'll try to un-patch the bpf.c change.
>
> At this point it is acting like the checksum offloading (which I did 
> disable on both the client and server) just isn't working.
>
> Will let you know.
>
> -Jon
>
> Danny Braniss wrote:
Tried a add-in em0 card - intel pro/1000 XT server card - 82544E chip - 
no change.

also tried with

ifconfig em0 -rxcsum
ifconfig em0 -txcsum
dhclient em0

No change. Packets still received with bad IP checksum.

Went back to bge0 now and reversed rev 178675 back to 172506 care of 
patch via 
http://svn.freebsd.org/viewvc/base/stable/7/sbin/dhclient/bpf.c?r1=172506&r2=178675&view=patch

Also no change. So this change to dhclient doesn't seem to be the issue. 
>From looking at 
http://svn.freebsd.org/viewvc/base/stable/7/sbin/dhclient/ this patch I 
took out is 7 months old, and I had this system running on 7-STABLE just 
fine about as of about 2-3 weeks ago. So it must have been something 
else in the sys/net or sys/netinet. I do seem some changes that are 3 
weeks old, 4 weeks, and 6 days for these directories on files that would 
effect the packet assembly.

Authors are julian, rwatson, and bz.

I'm going to look through these recent changes to try to find some that 
has to do with the checksum process.

-Jon


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