[Winpcap-users] pcap_findalldevs Hangs when called in Windows service

[matt jaffa]

So we added nm and NPF to dependencies to our service and the service
started up just fine. But within the Service it is hanging on the
pcap_findalldevs. So adding those two dependencies got it to start up but it
just sits there in the pcap_findalldevs call.

Does anyone have a working service which is using winpcap that just doesn't
hang in pcap_findalldevs?

Thanks

On 3/27/06, Bryan Kadzban <bryan at kadzban.is-a-geek.net> wrote:
>
> matt jaffa wrote:
> > Hi,
> >
> > When we are calling pcap_findalldevs in a Windows service the service
> > seems to hang in that function call.
>
> Your service needs to depend on NPF.
>
> The reason is that NPF is set up to start on demand (basically, when the
> first program makes a packet.dll or wpcap.dll call, the service will be
> started), not at startup.  When packet.dll loads (it's a dependency of
> wpcap.dll), it tries to start the NPF service for you, but since your
> service is starting, the service control manager is holding a lock.  It
> has to release the lock before any other service can start.  (Eventually
> something times out, NPF gets to start, packet.dll loads, and your
> service finishes starting up.)
>
> The fix is to make NPF start before your service; the only supported way
> to do this is to set a DependOnService REG_MULTI_SZ value in your
> service's registry key.  The data in the registry value should be the
> name of any services you depend on; setting it to NPF by itself is
> probably sufficient.
>
> Er, actually...  If you're using a new enough WinPcap version (probably
> 3.1 and newer), you'll also have to depend on the nm (Network Monitor)
> service.  (packet.dll loads up wanpacket.dll, which loads up another DLL
> that starts the nm service if it's needed.  So the same thing applies;
> nm has to be running before either packet.dll or wanpacket.dll get
> loaded.)  So set it to both NPF and nm.
>
>
> _______________________________________________
> Winpcap-users mailing list
> Winpcap-users at winpcap.org
> https://www.winpcap.org/mailman/listinfo/winpcap-users
>
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.winpcap.org/pipermail/winpcap-users/attachments/20060331/18db7733/attachment.htm