PyWFP

PyWFP is a Python interface for working with Windows Filtering Platform (WFP), allowing creation of network traffic filters using a similar Windivert-style syntax.

Note: PyWFP requires administrator privileges to run. Running without admin rights will result in a WFPError with code 0x00000005 (Access Denied).

Installation

pip install pywfp

Usage

from pywfp import PyWFP
from pprint import pprint


def main():
    # Create PyWFP instance
    pywfp = PyWFP()

    # Example filter string
    filter_string = (
        "outbound and tcp and remoteaddr == 192.168.1.3-192.168.1.4 " "and tcp.dstport == 8123 and action == block"
    )

    try:
        # Use context manager to handle WFP engine session
        with pywfp.session():
            # Add the filter
            filter_name = "PyWFP Block Filter"
            pywfp.add_filter(filter_string, filter_name=filter_name, weight=1000)

            # List existing filters
            filters = pywfp.list_filters()
            print(f"Found {len(filters)} WFP filters")

            # Find our specific filter
            if filter := pywfp.get_filter(filter_name):
                print(f"Found filter: {filter}")
                pprint(filter)

            # Keep the filter active until interrupted
            print("Press Ctrl+C to exit and remove the filter")
            try:
                while True:
                    input()
            except KeyboardInterrupt:
                print("Received Ctrl+C, cleaning up")

    except Exception as e:
        print(f"Error: {e}")


if __name__ == "__main__":
    main()

Supported Filters

PyWFP supports a variety of filter conditions that can be combined using logical AND operations. Here are the supported filter types:

Basic Filter Syntax

"outbound and tcp and remoteaddr == 192.168.1.3-192.168.1.4 and tcp.dstport == 8123 and action == allow"

Supported Conditions

IP Address Ranges

You can specify IP ranges using hyphen notation:

"remoteaddr == 192.168.1.1-192.168.1.255"

Multiple Conditions

Combine conditions using AND:

"outbound and tcp and remoteaddr == 192.168.1.1 and tcp.dstport == 80"

Filter Management

# You can set the weight of the filter to determine its priority. If weight is not specified, the highest priority will be given.
pywfp.add_filter("inbound and udp", filter_name="Block UDP", weight=500)

# List all filters
for filter in pywfp.list_filters():
    print(filter["name"])
)
# Maybe more to be added here

Testing

Unit Tests

Run unit tests with:

pytest -m "not integration"

Integration Tests

Integration tests require:

• Windows OS
• Administrator privileges
• Local network access

To run integration tests locally:

# Open an administrator command prompt
pytest -m integration