netsh trace1

Using Netsh to Capture Packets in Windows

A frequent visitor here will know that we have many articles discussing the netsh command line shell/scripting tool in Windows.  The tool was originally introduced in Win2K.  If you aren’t a regular – just click on ‘netsh’ in the tag cloud to see them all.

This article discusses how you can use the ‘netsh trace’ function to actually perform a packet capture from the command line in Windows.  Technically this means you do not need a capture tool on a Windows machine other than the OS itself.

To analyze and view the packets, you need a tool, and our favorite is Wireshark, of course!

Here is how to use netsh to accomplish this task.  

[Note: you may need to use Run as Administrator to get your system to work correctly]

We begin by examining the help screen with the following command:

netsh trace start ?

netsh trace1

 

You can see there are many options.

To do a simple trace/capture we will use the following command:

netsh trace start capture=yes traceFile="c:\netsh_trace.cap"

netsh trace2

The capture will run in the background.

To stop the capture, use the following command:

netsh trace stop

It will take several minutes to close.  Be patient!

netsh trace3

If we go and look at my directory c:\ we see the file was saved as follows:

netsh trace4

And if we try to open either of them in Wireshark, we get the following error:

netsh trace5

So you have to use something like Microsoft Message Analyzer (now retired – see their web page here: https://docs.microsoft.com/en-us/message-analyzer/installing-and-upgrading-message-analyzer ), or the older (now in archive, but still works) Microsoft Network Monitor (https://www.microsoft.com/en-us/download/details.aspx?id=4865) to open the file, and then you will be able to export it so you can analyze in Wireshark.

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