FAQ

Enough already! How does this work by example!?

#!/usr/bin/env ruby
require "rubygems"
require "pcaprub"

class CaptureExample

  def initialize()
    #interface configuration
    @dev = ::Pcap.lookupdev
    #promiscous_mode = true 
    @promiscous_mode = false 
    @timeout = 0 

    #packet information
    @capture_packets = 100
    @snaplength = 65535
    @bpf = "ip and not dst net 110.0.0.0/8" 
  end

  def getpackets
    system("ifconfig", @dev, "up")

    capture = ::Pcap.open_live(@dev, @snaplength, @promiscous_mode, @timeout)  
    capture.setfilter(@bpf)

    begin
      puts "Started capture..(#{@dev} => \"#{@bpf}\")"
      capture.each do |packet|
        # Handling the number of packets to process
        @capture_packets -= 1
        if @capture_packets == 0
          break
        end
      end

    # ^C to stop sniffing
    rescue Interrupt
      puts "\nPacket Capture stopped by interrupt signal."

    rescue Exception => e
      puts "\nERROR: #{e}"
      retry
    end

    puts "Captured #{100 - @capture_packets} packets"

    return capture

  end

end

mycapture = CaptureExample.new()
packet_capture = mycapture.getpackets
puts "capture.stats['recv'] = #{packet_capture.stats['recv']}"
puts "capture.stats['drop'] = #{packet_capture.stats['drop']}"