tcpflow in Kali Linux

tcpflow is a command-line tool used for capturing and analyzing network traffic. Unlike traditional packet capture tools that capture individual packets, tcpflow reconstructs entire TCP connections, making it easier to analyze data flows in a human-readable format.

Install tcpflow

Most Kali Linux installations come with tcpflow pre-installed. If it is missing, you can install it using:

$ sudo apt update && sudo apt-get install tcpflow

Basic Usage of tcpflow

To capture and analyze network traffic, run:

$ sudo tcpflow -i eth0

This command captures all TCP traffic on the network interface eth0 and saves the reconstructed flows in the current directory.

Filtering Traffic by Port

To capture traffic on a specific port (e.g., HTTP traffic on port 80):

$ sudo tcpflow -i eth0 port 80

This command filters only HTTP traffic for easy analysis.

Saving Output to a Specific Directory

You can specify a directory to save the captured data using:

$ sudo tcpflow -i eth0 -o /path/to/directory

Replace /path/to/directory with the desired location.

Reading Captured Data

Once data is captured, you can open and analyze the generated files using standard text editors or command-line tools:

$ cat /path/to/directory/192.168.1.1.0080-192.168.1.2.43210

This displays the contents of a reconstructed TCP flow.

tcpflow is an essential tool for network analysis and forensic investigations. By reconstructing TCP streams, it provides a clear view of network interactions, making debugging and monitoring easier.