[Winpcap-users] pcap_sendpacket to local adaptor (Sending tothe local machine)

[Fish" (David B. Trout]

Mark Pizzolato wrote:

[...]
> My experience comes from a very similar place.  I'm one
> of the authors of the network layer code for Bob Supnik's
> simh simulator family (http://simh.trailing-edge.com).

Cool! Looks neat. :)


[...]
>   2) Once #1 was fixed, on some systems I observed that
> Host to guest ICMP, UDP and TCP packets were being received
> by the network stack in the simulated system, but the stack
> was discarding these packets since they had invalid/garbage
> IP, ICMP, UDP, and TCP checksums.

Been there. Done that. Got the T-shirt.  :)


> This issue was due to the fact that all of these frames were
> being sent to the host NIC with the Windows IP stack assuming
> that the NIC would perform the various checksum computations
> due to the TOE (TCP Offload Engine) capabilities of the NICs
> on these systems.  Our receive code has now been modified to
> perform these checksum computations for all IPv4 frames
> originating from the host.

Exactly. Been there. Done that. Got the T-shirt.  :)

SPEAKING OF CHECKSUM OFFLOADING HOWEVER (with respect to WinPCap), I would
like to bring to Gianluca's (GV's) attention a LONG STANDING BUG in
WinPcap's[*] device driver bug that I've been meaning to report[+] for a
long time now. I shall report it in a subsequent post under the thread
title:

  "WinPCap driver BIOCSETOID / BIOCQUERYOID bug".


<snip>
> Thank you very much David for helping me see the light here.
> 
> - Mark Pizzolato

You're very welcome Mark. I'm glad I could help.


> By the way, your website http://www.softdevlabs.com seems offline
> (as does your fish at softdevlabs.com email address), I was able to
> look at some of your stuff in Google's cache though.

Must have been a temporary glitch. The server is actually in Paris, France
and is administered by a friend of mine (a fellow senior Hercules developer
as it turns out). Sometimes for whatever things go wrong requiring a reboot
and he doesn't notice it right away. Anyway it looks like it's working now
(or at least it is for me!).

Glad you found it in Google's cache. Another place you could probably have
found it is in the Internet Archive:

   http://web.archive.org

  (e.g. "http://web.archive.org/web/*/http://www.softdevlabs.com")


Their "Wayback Machine" is an INVALUABLE research tool.

-- 
"Fish" (David B. Trout) 
 fish at softdevlabs.com

[*] What's the proper capitalization/spelling of WinPCap anyway? Is it
"WinPCap" (capital C) or "WinPcap" (small c)? Capital C (i.e. WinPCap) seems
more logical to me, but I've seen it spelled with lowercase c so many time
I'm never sure. Maybe it's just a persistent typo that everyone keeps
making? Don't know. <shrug>

[+] The only reason I haven't reported it yet is because I *was* hoping to
build the driver for myself first, but alas I can never seem to find the
time.  (sigh!)  :(