pypcap

import pcap import os import sys try: # Try to find a default network device dev = pcap.lookupdev() if dev is None: print("No default network device found. Attempting to list all devices...") all_devs = pcap.findalldevs() if not all_devs: print("No network devices available on this system.") sys.exit(1) dev = all_devs[0] # Use the first available device as a fallback print(f"Using first available device: {dev}") # Allow overriding the device from an environment variable for easier testing capture_device = os.environ.get('PCAP_DEV', dev) print(f"Attempting to capture on device: {capture_device}") pc = pcap.pcap(capture_device) # Optional: Set a BPF filter (e.g., 'tcp port 80' or 'udp') # pc.setfilter('tcp') print("Starting packet capture (press Ctrl+C to stop)...") for ts, pkt in pc: # ts is the timestamp (float), pkt is the raw packet bytes print(f"[{ts}] Captured packet of length: {len(pkt)} bytes") # For detailed parsing, consider libraries like scapy or dpkt except pcap.PcapError as e: print(f"Error initializing pcap: {e}") print("\nCommon issues:\n1. Lack of permissions: Try running with `sudo` (e.g., `sudo python your_script.py`).\n2. Device not found: Check if '{capture_device}' is the correct interface name (use `pcap.findalldevs()` to list).\ 3. `libpcap` not installed: Ensure `libpcap-dev` (Linux) or `libpcap` (macOS) is installed.") sys.exit(1) except KeyboardInterrupt: print("\nCapture stopped by user.") except Exception as e: print(f"An unexpected error occurred: {e}") sys.exit(1)