[Winpcap-users] Error Starting NPF

Gianluca Varenni gianluca.varenni at cacetech.com
Wed May 27 08:27:01 PDT 2009

It can definitely be.

Can you please check the properties of c:\windows\system32\drivers\npf.sys?

In the case of the x64 driver, the description of the driver should be

npf.sys (NT5/6 AMD64) Kernel Driver

Have a nice day

----- Original Message ----- 
From: "Fish" <fish at infidels.org>
To: <winpcap-users at winpcap.org>
Sent: Tuesday, May 26, 2009 8:34 PM
Subject: Re: [Winpcap-users] Error Starting NPF

> Hash: SHA1
> I am not saying this is what the problem is, but I can state that I
> personally experienced this very issue a long time ago whenever I
> first began playing around with x64. In my particular case it was x64
> windows complaining that the driver it was trying to load was not a
> 64-bit driver. Somehow things got setup such that the 32-bit driver
> was always trying to be loaded which does not work on 64-bit Windows.
> On 64-bit Windows all drivers must be 64-bit. Either that or the
> opposite: a 64-bit driver was trying to be loaded by 32-bit Windows.
> Again, I'm not stating that is your problem, only that the "Driver
> has been blocked from loading" error message you mention was
> experienced by myself for the reasons described.
> Hope that helps.
> - --
> "Fish" (David B. Trout) - fish at softdevlabs.com
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>  -----Original Message-----
>  From: winpcap-users-bounces at winpcap.org
> [mailto:winpcap-users-bounces at winpcap.org]On Behalf Of Andy Merrill
>  Sent: Tuesday, May 26, 2009 10:49 AM
>  To: winpcap-users at winpcap.org
>  Subject: [Winpcap-users] Error Starting NPF
>  I'm getting an odd error when I try to run WireShark. So I started
> doing some digging and found that WinPcap 4.0.2 is not starting up.
> I've used it plenty of times in the past on other systems, but on
> this specific box I get an error in the Event Logs that says:
>  "The NetGroup Packet Filter Driver service failed to start due to
> the following error:
>  This driver has been blocked from loading "
>  So I tried to start it via command line with "net start npf" and
> got pretty much the same error of:
>  "System error 1275 has occurred.
>  This driver has been blocked from loading"
>  Anyone have an idea why the drivers might be failing to load?
>  This is on a Windows Server 2003 system running in a VPS.
>  Thanks,
>  Andy Merrill
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> =ExiA


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