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Author Topic: WinPCap issues - no npf.sys file on my system  (Read 24726 times)

TheGregster

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WinPCap issues - no npf.sys file on my system
« on: November 29, 2010, 08:55 AM »
Hi Mouser!  Have an odd problem here.  URL Snooper seems to install fine, but when WinPCap tries to install, I'm told that it can't open "c:\windows\system32\drivers\npf.sys" for writing.  Didn't take look to figure out why - it doesn't exist on my system... anywhere, not just in the "c:\windows\system32\drivers folder."  I'm running Windows 7, 64 bit (which is likely the problem).  If I tell it to install anyway, URL Snooper doesn't see any network adapters. No surprise there.  Was wondering if you have any thoughts on this.  If so, thanks!  If not, I'd appreciate it if you could drop everything else you're doing, re-write URL Snooper from the ground up, and eliminate the need for WinPCap entirely.  Oh yeah, then drive it over to my house and install it for me to make sure it works...   Thanks!   ;D

Greg

worstje

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Re: WinPCap issues - no npf.sys file on my system
« Reply #1 on: November 29, 2010, 01:31 PM »
I haven't installed Winpcap in a while, nor used this one.. but I bet it is trying to _write_ said file and doesn't have the permissions, hence it not existing. Did you try running that install with administrative privileges?

TheGregster

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Re: WinPCap issues - no npf.sys file on my system
« Reply #2 on: November 29, 2010, 03:30 PM »
That's an excellent suggestion - will try it and post the results - thanks!

TheGregster

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Re: WinPCap issues - no npf.sys file on my system
« Reply #3 on: November 29, 2010, 04:34 PM »
Aw nuts, didn't work.  I appreciate the suggestion though.  I'm going to try to attach a screen cap of the error. Never done this before, so forgive me if I make a mess...

Greg

WinPcap error.png

worstje

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Re: WinPCap issues - no npf.sys file on my system
« Reply #4 on: November 29, 2010, 10:29 PM »
Try using Process Monitor (not Process Explorer) from Sysinternals. It's a bit of an unwieldy utility, but if you set up a filter for the installer (or maybe for the path in question, either ought to work) and then reproduce your issue, maybe you can see why it fails to open it as it ought to display the reason for the failure. I find it hard to believe it is a problem everyone running Windows 7 has as most packet-inspection utilities lean heavily on WinPcap.

Alternatively, try installing another program that comes with Winpcap? I seem to recall software bundling it with their apps to make them easier to use. An example of such a program would be Nmap. (It's kind of a hack, but probably easier than debugging the problem like I suggested just now since it wouldn't garantuee a fix...)

PhilB66

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Re: WinPCap issues - no npf.sys file on my system
« Reply #5 on: November 29, 2010, 11:18 PM »
Download the latest version of WinPcap (Version 4.1.2, 02 jul 10). The one you are trying to install had a bug. See here
« Last Edit: November 29, 2010, 11:20 PM by PhilB66 »

TheGregster

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Re: WinPCap issues - no npf.sys file on my system
« Reply #6 on: December 01, 2010, 11:00 PM »
Wow guys, appreciate all the help here.  I'll try installing the new version first, and if that doesn't work, I'll try worstje's suggestion.  I'll post the results, and again, thank you for the help on this   :)

Greg

unixgreybeard

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Re: WinPCap issues - no npf.sys file on my system
« Reply #7 on: June 04, 2022, 05:10 PM »
This necrothread is the top google search hit for this problem, so I actually registered just so I could reply with my solution:

With window open saying
no npf.sys file - Abort Retry Ignore
...etc. leave window open

Open cmd.exe as administrator

Side note about how I'm illustrating these commands: When demonstrating commands in a Unix-like environment, the convention is to use
$
to denote user command prompt, and
#
to denote root (elevated) command prompt, but I am unsure if such a convention for Windows exists. Therefore, I am going to use
%CD%:\>
to denote the following string is a command to be invoked at the command prompt in your current working directory, as it is the environment variable for current directory. 

%CD%:\> cd %SYSTEMROOT%\System32\drivers
(this is usually C:\Windows\System32\Drivers)

%CD%:\> dir npf.sys
to verify the file exists and is present

%CD%:\> rename npf.sys npf-original.sys
to move the file out of the way so you can install the new one

Hit
Retry
in your installer Window.  This worked for me on the first try, and has the benefit of not removing any original files in case there's some incompatibility or other reason necessary to restore the previous version of
npf.sys
file.

OK that's all, really this was a lot more simple than anyone's making it out to be. Hope people scroll all the way through before the start trying all the other crazy stuff people suggested above (not that they're bad ideas, just totally beyond the scope of what's necessary).

Good luck!
« Last Edit: June 04, 2022, 05:17 PM by unixgreybeard, Reason: was missing cd command »