[Winpcap-users] SPAM: Re: Telling the difference between devices

Joe Anello joe.anello at roadrunner.com
Wed Nov 21 10:30:22 PST 2012

Thanks for that tidbit.  I was away for a couple of days and just figured
that out a little while ago, so thanks for the confirmation.

I've gotten a few replies from folks who have suggested that simultaneous
capture on multiple ports doesn't work, but that has me very confused...

Wireshark is using the WinPcap library and I can select two ports with
wireshark to monitor. It seems to work ok there.  Does anyone know if this
is an illusion, if Wireshark has custom code, or if there is a stability
problem with it.

-----Original Message-----
From: winpcap-users-bounces at winpcap.org
[mailto:winpcap-users-bounces at winpcap.org] On Behalf Of Guy Harris
Sent: Wednesday, November 21, 2012 12:47 PM
To: winpcap-users at winpcap.org
Subject: SPAM: Re: [Winpcap-users] Telling the difference between devices

On Nov 20, 2012, at 9:34 AM, Sam Roberts <vieuxtech at gmail.com> wrote:

> On Mon, Nov 19, 2012 at 9:44 AM, Joe Anello <joe.anello at roadrunner.com>
>> I'm sure it is in the documentation, but I just can't seem to find it.
> Better to read the source.
>> I have a Windows based system with 6 GigE ports (all based on the same
>> chips).  When I call pcap_findalldevs, it returns a list that contains 6
>> IDENTICAL strings for the ports. Pcap_open_live expects me to pass it
>> identification string, but since they are all the same, how do I identify
>> which of the 6 ports I want to open?
> You mean in struct pcap_if, the .name fields are all the same, or the
> .description fields?

...because the .name field is what should be passed to pcap_open_live(), not
the description field.

There is no guarantee that the description field will be different for all
interfaces - on Windows (i.e., in WinPcap rather than in libpcap on various
UN*Xes), it comes from the "vendor description" supplied by the driver,
which describes the adapter's hardware (or, in some cases, describes an
intermediate driver), so if you have multiple adapters of the same type, the
descriptions will be identical.

I suspect that the .name field is *not* the same for all the adapters.
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