##
# This file is part of the Metasploit Framework and may be subject to
# redistribution and commercial restrictions. Please see the Metasploit
# web site for more information on licensing and terms of use.
#   http://metasploit.com/
##

require 'msf/core'

class Metasploit3 < Msf::Auxiliary

	include Msf::Exploit::Capture
	include Msf::Auxiliary::Scanner
	include Msf::Auxiliary::Report

	def initialize
		super(
			'Name'        => 'TCP ACK Firewall Scanner',
			'Description' => %q{
				Map out firewall rulesets with a raw ACK scan.  Any
				unfiltered ports found means a stateful firewall is
				not in place for them.
			},
			'Author'      => 'kris katterjohn',
			'License'     => MSF_LICENSE
		)

		register_options([
			OptString.new('PORTS', [true, "Ports to scan (e.g. 22-25,80,110-900)", "1-10000"]),
			OptInt.new('TIMEOUT', [true, "The reply read timeout in milliseconds", 500]),
			OptInt.new('BATCHSIZE', [true, "The number of hosts to scan per set", 256]),
			OptString.new('INTERFACE', [false, 'The name of the interface'])
		], self.class)

		deregister_options('FILTER','PCAPFILE')
	end

	# No IPv6 support yet
	def support_ipv6?
		false
	end

	def run_batch_size
		datastore['BATCHSIZE'] || 256
	end

	def run_batch(hosts)
		open_pcap

		pcap = self.capture

		ports = Rex::Socket.portspec_crack(datastore['PORTS'])

		if ports.empty?
			print_error("Error: No valid ports specified")
			return
		end

		to = (datastore['TIMEOUT'] || 500).to_f / 1000.0

		# Spread the load across the hosts
		ports.each do |dport|
			hosts.each do |dhost|
				shost, sport = getsource(dhost)

				pcap.setfilter(getfilter(shost, sport, dhost, dport))

				begin
					probe = buildprobe(shost, sport, dhost, dport)

					capture_sendto(probe, dhost)

					reply = probereply(pcap, to)

					next if not reply

					print_status(" TCP UNFILTERED #{dhost}:#{dport}")

					#Add Report
					report_note(
						:host	=> dhost,
						:proto	=> 'tcp',
						:port	=> dport,
						:type	=> "TCP UNFILTERED #{dhost}:#{dport}",
						:data	=> "TCP UNFILTERED #{dhost}:#{dport}"
					)

				rescue ::Exception
					print_error("Error: #{$!.class} #{$!}")
				end
			end
		end

		close_pcap
	end

	def getfilter(shost, sport, dhost, dport)
		# Look for associated RSTs
		"tcp and (tcp[13] & 0x04) != 0 and " +
		"src host #{dhost} and src port #{dport} and " +
		"dst host #{shost} and dst port #{sport}"
	end

	def getsource(dhost)
		# srcip, srcport
		[ Rex::Socket.source_address(dhost), rand(0xffff - 1025) + 1025 ]
	end

	def buildprobe(shost, sport, dhost, dport)
		p = PacketFu::TCPPacket.new
		p.ip_saddr = shost
		p.ip_daddr = dhost
		p.tcp_sport = sport
		p.tcp_ack = rand(0x100000000)
		p.tcp_flags.ack = 1
		p.tcp_dport = dport
		p.tcp_win = 3072
		p.recalc
		p
	end

	def probereply(pcap, to)
		reply = nil
		begin
			Timeout.timeout(to) do
				pcap.each do |r|
					pkt = PacketFu::Packet.parse(r)
					next unless pkt.is_tcp?
					reply = pkt
					break
				end
			end
		rescue Timeout::Error
		end
		return reply
	end

end