mcpcap

Instructions

Implementation Reference

• src/mcpcap/modules/capinfos.py:20-39 (handler)

  The primary handler function for the 'analyze_capinfos' tool. It delegates to analyze_packets for processing local or remote PCAP files.
  def analyze_capinfos(self, pcap_file: str) -> dict[str, Any]: """ Return metadata from a PCAP file, similar to Wireshark's capinfos utility. IMPORTANT: This tool expects a FILE PATH or URL, not file content. - For local files: "/path/to/capture.pcap" - For remote files: "https://example.com/capture.pcap" - File uploads are NOT supported - save the file locally first Args: pcap_file: Path to local PCAP file or HTTP URL to remote PCAP file (NOT file content - must be a path or URL) Returns: A structured dictionary containing PCAP metadata including: - File information (size, name, encapsulation type) - Packet statistics (count, data size, average sizes) - Temporal data (duration, timestamps, rates) """ return self.analyze_packets(pcap_file)
• src/mcpcap/core/server.py:56-57 (registration)

  Registration of the analyze_capinfos tool with the FastMCP server instance.
  elif module_name == "capinfos": self.mcp.tool(module.analyze_capinfos)
• src/mcpcap/modules/capinfos.py:41-62 (helper)

  Implements the core PCAP analysis logic specific to capinfos, reading packets with rdpcap, generating stats, and collecting file metadata.
  def _analyze_protocol_file(self, pcap_file: str) -> dict[str, Any]: """Perform the actual information gathering on a local PCAP file.""" try: packets = rdpcap(pcap_file) # Generate statistics stats = self._generate_statistics(packets) results = { "file_size_bytes": os.path.getsize(pcap_file), "filename": os.path.basename(pcap_file), "file_encapsulation": self._detect_linktype(pcap_file), } return results | stats except Exception as e: return { "error": f"Error reading PCAP file '{pcap_file}': {str(e)}", "file": pcap_file, }
• src/mcpcap/modules/capinfos.py:63-92 (helper)

  Helper function to detect and map the PCAP linktype (encapsulation type) to a human-readable name.
  def _detect_linktype(self, path: str) -> str: """Detect the linktype and try to map it to a human-readable encapsulation type. Args: path: Path to the packet capture Returns: Detected link-layer header (linktype) """ # mapping based on pcap-linktype(7) and https://github.com/wireshark/wireshark/blob/master/wiretap/wtap.c#L656 LINKTYPE_MAP = { 1: "Ethernet", 101: "Raw IP", 105: "IEEE 802.11 Wireless LAN", 113: "Linux cooked-mode capture v1", 228: "Raw IPv4", 229: "Raw IPv6", 276: "Linux cooked-mode capture v2", } try: with PcapReader(path) as reader: linktype = getattr(reader, "linktype", None) except Exception: linktype = None return LINKTYPE_MAP.get( linktype, f"Unknown ({linktype})" if linktype else "Unknown" )
• src/mcpcap/modules/capinfos.py:93-119 (helper)

  Helper function to compute packet statistics like count, sizes, rates, and timestamps from packet list.
  def _generate_statistics(self, packet_details: list) -> dict[str, Any]: """Return metadata about the capture file, similar to capinfos(1) utility.""" if not packet_details: return {"error": "No packets found"} packet_count = len(packet_details) data_size = sum(len(pkt) for pkt in packet_details) first_time = float(packet_details[0].time) last_time = float(packet_details[-1].time) duration = max(last_time - first_time, 0.000001) data_byte_rate = data_size / duration if duration > 0 else 0 data_bit_rate = (data_size * 8) / duration if duration > 0 else 0 avg_packet_size = data_size / packet_count if packet_count > 0 else 0 avg_packet_rate = packet_count / duration if duration > 0 else 0 return { "packet_count": packet_count, "data_size_bytes": data_size, "capture_duration_seconds": duration, "first_packet_time": first_time, "last_packet_time": last_time, "data_rate_bytes": data_byte_rate, "data_rate_bits": data_bit_rate, "average_packet_size_bytes": avg_packet_size, "average_packet_rate": avg_packet_rate, }
• src/mcpcap/modules/base.py:43-57 (helper)

  Base class helper method dispatched by the handler; handles local/remote PCAP files and calls protocol-specific analysis.
  def analyze_packets(self, pcap_file: str) -> dict[str, Any]: """Analyze packets from a PCAP file (local or remote). Args: pcap_file: Path to local PCAP file or HTTP URL to remote PCAP file Returns: A structured dictionary containing packet analysis results """ # Check if this is a remote URL or local file if pcap_file.startswith(("http://", "https://")): return self._handle_remote_analysis(pcap_file) else: return self._handle_local_analysis(pcap_file)