TCP Flag Filter

This is a simple command line application that lets a user obtain information about packets filtered according to any of the TCP header flags. Built with Python (v3.6.9), this can useful tool for network traffic analysis, if used in tandem with other network analysis tools.

How it Works

Input

The application takes a network traffic file of the .pcap file type as input

Output

The application provides the user with a file named flag_data.txt as output. It contains the following data for every packet in the traffic file containing the requested header flag:

• Source Port : Source port of the packet
• Destination Port : Destination port of the packet
• Source IP Address : Source IP address of the packet
• Destination IP Address : Destination IP address of the packet
• Flags Present : A space separated list of flags present on that particular packet

Files involved

The following are the files involved in the entire application.

• sample_capture.pcap : Packet capture file from any network
• flag_data.txt : Packet information about the filtered TCP packets

Get it running

Prerequisites

• Clone the repository from here using the following command

git clone https://github.com/Parthiv-M/tcp-flag-filter

• Have Python installed on your system, at least version >= 3.6
• Install the external modules required from the requirements.txt file with the following command

pip install -r requirements.txt

Running the command line application

Run the command line application with the following commands

python3 tcp_searcher.py

This should get you started with analysing TCP packets based on header flag bits

Screenshots

The menu presented to users

The menu is prompted again after the user enters a valid file name

A summary of the traffic file is given to the user

Upon entering a valid TCP flag, a file with the relevant packet details is generated

The file containing packet details of the filtered packets

Contributors

Parthiv Menon and Dhyan Gandhi worked on this project as part of the Mini-Project for Computer Networking.