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WinpktFilter filters that create a port mirror across layer 3 windows computers
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Creates a port mirror inside a GRE tunnel. Useful when one needs to create a port mirror and doesn't have access to the necessary network equipment, or when mirroring to a HA VM which may move host ocassionally.


gretunnel sniffs TCP/UDP packets from an interface and sends them out the same or different interface to the specified destination encapsulated in a GRE header.

Usage: gretunnel.exe dst-ip src-ip listen-index send-index
         dst-ip         destination IP address
         src-ip         source IP address
         listen-index   adapter index to listen on
         send-index     adapter index to send on


Removes GRE headers from packets.

Usage: grestrip.exe iIndex 
         iIndex     adapter index to strip GRE headers from


  1. Install the WinpktFilter runtime from on source and destination machines
  2. On source machine, run gretunnel
  3. On destination machine, create firewall exception for GRE (IP protocol 47)
  4. On destination machine, run grestrip
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