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local coroutine = require "coroutine"
local dns = require "dns"
local ipOps = require "ipOps"
local nmap = require "nmap"
local stdnse = require "stdnse"
local string = require "string"
local tab = require "tab"
local table = require "table"
description = [[
Performs a quick reverse DNS lookup of an IPv6 network using a technique
which analyzes DNS server response codes to dramatically reduce the number of queries needed to enumerate large networks.
The technique essentially works by adding an octet to a given IPv6 prefix
and resolving it. If the added octet is correct, the server will return
NOERROR, if not a NXDOMAIN result is received.
The technique is described in detail on Peter's blog:
http://7bits.nl/blog/2012/03/26/finding-v6-hosts-by-efficiently-mapping-ip6-arpa
]]
---
-- @usage
-- nmap --script dns-ip6-arpa-scan --script-args='prefix=2001:0DB8::/48'
--
-- @output
-- Pre-scan script results:
-- | dns-ip6-arpa-scan:
-- | ip ptr
-- | 2001:0DB8:0:0:0:0:0:2 resolver1.example.com
-- |_2001:0DB8:0:0:0:0:0:3 resolver2.example.com
--
-- @args prefix the ip6 prefix to scan
-- @args mask the ip6 mask to start scanning from
author = "Patrik Karlsson"
license = "Same as Nmap--See https://nmap.org/book/man-legal.html"
categories = {"intrusive", "discovery"}
local arg_prefix = stdnse.get_script_args(SCRIPT_NAME .. ".prefix")
local arg_mask = stdnse.get_script_args(SCRIPT_NAME .. ".mask")
-- Return a prefix and mask based on script arguments. First checks for "/"
-- netmask syntax; then looks for a "mask" script argument if that fails. The
-- "/" syntax wins over "mask" if both are present.
local function get_prefix_mask(arg_prefix, arg_mask)
if not arg_prefix then
return
end
local prefix, mask = string.match(arg_prefix, "^(.*)/(.*)$")
if not mask then
prefix, mask = arg_prefix, arg_mask
end
return prefix, mask
end
prerule = function()
local prefix, mask = get_prefix_mask(arg_prefix, arg_mask)
return prefix and mask
end
local function query_prefix(query, result)
local condvar = nmap.condvar(result)
local status, res = dns.query(query, { dtype='PTR' })
if ( not(status) and res == "No Answers") then
table.insert(result, query)
elseif ( status ) then
local ip = query:sub(1, -10):gsub('%.',''):reverse():gsub('(....)', '%1:'):sub(1, -2)
ip = ipOps.bin_to_ip(ipOps.ip_to_bin(ip))
table.insert(result, { ptr = res, query = query, ip = ip } )
end
condvar "signal"
end
action = function()
local prefix, mask = get_prefix_mask(arg_prefix, arg_mask)
local query = dns.reverse(prefix)
-- cut the query name down to the length of the prefix
local len = (( mask / 8 ) * 4) + #(".ip6.arpa") - 1
local found = { query:sub(-len) }
local threads = {}
local i = 20
local result
repeat
result = {}
for _, f in ipairs(found) do
for q in ("0123456789abcdef"):gmatch("(%w)") do
local co = stdnse.new_thread(query_prefix, q .. "." .. f, result)
threads[co] = true
end
end
local condvar = nmap.condvar(result)
repeat
for t in pairs(threads) do
if ( coroutine.status(t) == "dead" ) then threads[t] = nil end
end
if ( next(threads) ) then
condvar "wait"
end
until( next(threads) == nil )
if ( 0 == #result ) then
return
end
found = result
i = i + 1
until( 128 == i * 2 + mask )
table.sort(result, function(a,b) return (a.ip < b.ip) end)
local output = tab.new(2)
tab.addrow(output, "ip", "ptr")
for _, item in ipairs(result) do
tab.addrow(output, item.ip, item.ptr)
end
return "\n" .. tab.dump(output)
end
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