gistfile1.js

#!/usr/bin/env node

var sys = require('sys'),
    path = require('path'),
    fs = require('fs'),
    pcap = require('pcap'), pcap_session,
    tcp_tracker = new pcap.TCP_tracker();

var device = undefined;
var filter = "";

for (var i=2; i < process.argv.length; i++) {
  var arg = process.argv[i];
  if (arg == '-h' || arg == '--help') {
    console.log('usage: zipline [options] [interface|capture file]\n');
    console.log('Options:');
    console.log('  -f, --filter');
    console.log('  Specify a pcap capture filter. See "man pcap-filter" for syntax.\n');
    console.log('  -l, --list');
    console.log('  Lists available network interfaces.\n');
    console.log('Examples:');
    console.log('  zipline');
    console.log('  Monitor all packets on the default network interface.\n');
    console.log('  zipline en0');
    console.log('  Monitor all packets on ethernet interface en0.\n');
    console.log('  zipline en0 -f "tcp port 80"');
    console.log('  Monitor TCP packets sent to or from port 80 on ethernet interface en0.\n');
    console.log('  zipline example.pcap');
    console.log('  Replay all packets from the capture file example.pcap.\n');
    console.log('  zipline example.pcap -f "tcp port 80"');
    console.log('  Replay TCP packets sent to or from port 80 in the capture file example.pcap.\n');
    process.exit(0);
  } else if (arg == '-f' || arg == '--filter') {
    if (process.argv.length > i + 1) {
      filter = process.argv[++i];
    } else {
      console.error('No filter specified!');
      process.exit(1);
    }
  } else if (arg == '-l' || arg == '--list') {
    var session = pcap.createSession();

    // Print all devices, default device prefixed with an asterisk
    session.findalldevs().forEach(function (dev) {
      if (session.device_name === dev.name) {
        sys.print('*');
      } else {
        sys.print(' ');
      }

      sys.print(dev.name + ' ');
      if (dev.addresses.length > 0) {
        dev.addresses.forEach(function (address) {
          sys.print(address.addr + ' ');
        });
      } else {
        sys.print('Not connected');
      }

      sys.print("\n");
    });
    process.exit(0);
  } else {
    if (device === undefined) {
      device = arg;
    } else {
      console.error('Unknown argument "' + arg + '"');
      process.exit(1);
    }
  }
}


// Start up pcap
if (device !== undefined) {
  // Use offline mode if the device is a capture file, otherwise start
  // a live session on the specified device
  path.exists(device, function (exists) {
    if (exists) {
      pcap_session = pcap.createOfflineSession(device, filter);
    } else {
      pcap_session = pcap.createSession(device, filter);
      console.log("Listening on " + pcap_session.device_name);
    }
    start();
  });
} else {
  pcap_session = pcap.createSession(device, filter);
  console.log("Listening on " + pcap_session.device_name);
  start();
}

function start() {
  // Packets are now flowing whether in online or offline mode
  pcap_session.addListener('packet', function (raw_packet) {
    var packet = pcap.decode.packet(raw_packet);
    sys.puts(pcap.print.packet(packet));
  });
}