[Winpcap-users] winpcap and ip change

Gianluca Varenni gianluca.varenni at cacetech.com
Fri Oct 1 14:47:23 PDT 2010

This looks like some reconfiguration of the entire network stack for that 
particular NIC.

Did you try on a pre-vista machine, or a cleanly installed vista/7 (no 
firewalls, antivirus, nothing at all)?

Have a nice day

From: "Thorsten Stoffregen" <thorsten.stoffregen at gmx.de>
Sent: Friday, September 24, 2010 11:19 AM
To: <winpcap-users at winpcap.org>
Subject: Re: [Winpcap-users] winpcap and ip change

> Hi david,
>> > pcap_close(pcap_t ...);
>> > changeIp(.....);
>> > Sleep(5000);
>> > pcap_open(pcap_t ...);
>> May open a new capture BEFORE you change the IP and read from BOTH
>> streams during that 5 second period?
>> Then once the 5 seconds have passed, close the original stream and
>> continue reading from only the new stream?
> It doesn't work if I don't close the capture. Even when I
> close, wait and open the device within my software and wireshark is
> running and capturing on the same device, the capture stops, no
> more packeges.
> Only if I stop and restart wireshark capture and my application
> after the change it will capture agein
> (took me a couple of hours, because wireshark is
> running almost all the time while I'm testing...).
>> Or maybe there's a way to change the IP address of the adapter WITHOUT
>> using netsh? (Maybe there's a command (OID?) you can send to the
>> adapter to assign a new IP without disabling/re-enabling
>> (unbinding/rebinding) the adapter (which is what I believe netsh is
>> probably doing))?? I haven't looked but there might be something
>> better than netsh.
> I tried netsh and the WMI command EnableStatic (with C#)
> http://msdn.microsoft.com/en-us/library/aa390383%28v=VS.85%29.aspx
> both methods shows the same behavior. If you now another better
> way to change the Ip please let me know. The hole application is
> written in C (runs on Linux, VxWorks, Windows),
> only for the Ip change I used an mixed code
> (managed/unmanaged) Dll to fire the WMI Command.
>> "Gianluca Varenni" worte:
>> In general, changing the IP address should not cause this effect (it's
>> something inside the tcp/ip stack, WinPcap works in parallel with it).
>> Unless the IP address change causes some changes in some NDIS 
>> intermediate
>> driver (so below WinPcap) and there is some unbinding/binding going on.
> Hm, maybe the "EnableStatic" command is causing the trouble, even if
> DHCP is switched of all the time.
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