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#!/usr/bin/env ruby
# main.rb
# 4 de octubre de 2007
#
begin
require 'dhcp'
require 'net/dhcp'
require 'socket'
require 'pcaplet'
rescue LoadError
STDERR.puts "Unable to load a required library. Please ensure you have installed the following gems:"
STDERR.puts " dhcp, ipaddress, ruby-pcap"
STDERR.puts "\nError was: #{$!.message}"
exit 1
end
server_thread = Thread.new do
s = "Packets received by the filter:\n"
s << '-'*s.size + "\n"
dhcpdump = Pcaplet.new('-s 4096')
DHCP_PACKET = Pcap::Filter.new('port 67 or port 68', dhcpdump.capture)
dhcpdump.add_filter(DHCP_PACKET)
dhcpdump.each_packet {|pkt|
msg = DHCP::Message.from_udp_payload(pkt.udp_data)
s << "#{pkt.src}:#{pkt.sport} > #{pkt.dst}:#{pkt.dport}\n"
s << msg.to_s
puts s if s
}
end
discover = DHCP::Discover.new
payload = discover.pack
sckt = UDPSocket.new
sckt.setsockopt(Socket::SOL_SOCKET, Socket::SO_BROADCAST,true)
sckt.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, true)
sckt.bind('', 68)
sckt.send(payload, 0, "<broadcast>", 67)
trap('INT') {server_thread.kill}
server_thread.join
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