This is a packet sniffer implementation in Python that allows you to capture and analyze network packets using the Scapy library. With this code, you can specify a network interface to sniff on, apply a BPF filter to customize which packets are captured, and write the captured packets to a PCAP file if desired. You can also specify a network tap device to use to capture all traffic on a network segment, and use SSLstrip to downgrade HTTPS connections to HTTP. The script prints a summary of each packet captured and waits for a keyboard interrupt (Ctrl-C) to stop the sniffer. If an output file is specified, the captured packets are written to the file in PCAP format when the sniffer is stopped.
To use this code, you will need the following:
Python 3.6 or later The Scapy library, which you can install using pip install scapy
The SSLstrip tool, which you can install using pip install sslstrip
Root privileges to run the packet sniffer on a network interface (you can use sudo to run the script with root privileges)
Save the code to a file, such as packet_sniffer.py.
Run the script with the -i flag to specify the network interface to sniff on, and optional -f, -o, and -t flags to specify a BPF filter, output file, and network tap device.
For example: ./packet_sniffer.py -i eth0 -f "tcp port 80" -o http_traffic.pcap -t tap0
This will start SSLstrip on the eth0 interface, start the sniffer on the tap0 device, and only capture TCP packets on port 80, writing the packets to the http_traffic.pcap file.
Here are some common issues that you may encounter when using this code:
Permission issues: Packet sniffing requires low-level access to network interfaces, which may not be granted to all users. To overcome this, you can run the packet sniffer with root privileges using sudo.
Filtering out noise: On busy networks, you may receive a large volume of packets that are not relevant to your analysis. You can use BPF filters to specify the types of packets you want to capture, or add additional filtering logic to your code to exclude unwanted packets.
Handling encrypted traffic: Encrypted traffic cannot be easily analyzed, as the contents of the packets are not visible. One solution is to use a tool like SSLstrip to downgrade HTTPS connections to HTTP, allowing you to analyze the unencrypted traffic. However, this can be a security risk and should be used with caution.
Capturing packets from other hosts: By default, most sniffers will only capture packets that are sent to or from the host running the sniffer. To capture packets from other hosts, you will need to use a network tap or switch that allows you to see all of the traffic on a network segment.
Handling large volumes of traffic: If you are capturing packets at high rates or for extended periods of time, you may need to optimize your code to handle the large volume of data efficiently. One option is to use a tool like TShark, which is optimized for high-speed packet capture and can write packets directly to disk.