description = [[ Gets the time and configuration variables from an NTP server. We send two requests: a time request and a "read variables" (opcode 2) control message. Without verbosity, the script shows the time and the value of the version, processor, system, refid, and stratum variables. With verbosity, all variables are shown. See RFC 1035 and the Network Time Protocol Version 4 Reference and Implementation Guide (http://www.eecis.udel.edu/~mills/database/reports/ntp4/ntp4.pdf) for documentation of the protocol. ]] --- -- @output -- PORT STATE SERVICE VERSION -- 123/udp open ntp NTP v4 -- | ntp-info: -- | receive time stamp: Sat Dec 12 16:22:41 2009 -- | version: ntpd 4.2.4p4@1.1520-o Wed May 13 21:06:31 UTC 2009 (1) -- | processor: x86_64 -- | system: Linux/2.6.24-24-server -- | stratum: 2 -- |_ refid: 195.145.119.188 author = "Richard Sammet" license = "Same as Nmap--See http://nmap.org/book/man-legal.html" categories = {"default", "discovery", "safe"} require "bin" require "nmap" require "stdnse" require "comm" require "shortport" portrule = shortport.port_or_service(123, "ntp", {"udp", "tcp"}) -- This script run against open|filtered ports, so don't wait too long if -- there's no response. local TIMEOUT = 5000 -- Transform an array into a table where the array's values all map to true. local function make_set(a) local i, v, result result = {} for i, v in ipairs(a) do result[v] = true end return result end -- Only these fields from the response are displayed with default verbosity. local DEFAULT_FIELDS = make_set({"version", "processor", "system", "refid", "stratum"}) action = function(host, port) local status local buftres, bufrlres local output = {} -- This is a ntp v4 mode3 (client) date/time request. local treq = string.char(0xe3, 0x00, 0x04, 0xfa, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00) -- This is a ntp v2 mode6 (control) rl (readlist/READVAR(2)) request. See -- appendix B of RFC 1305. local rlreq = string.char(0x16, 0x02, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00) status, buftres = comm.exchange(host, port, treq, {proto=port.protocol, timeout=TIMEOUT}) if not status then -- Don't try the second probe if this one didn't work. return nil else local _, sec, frac, tstamp _, sec, frac = bin.unpack(">II", buftres, 33) -- The NTP epoch is 1900-01-01, so subtract 70 years to bring the date into -- the range Lua expects. The number of seconds at 1970-01-01 is taken from -- the NTP4 reference above. tstamp = sec - 2208988800 + frac / 0x10000000 table.insert(output, string.format("receive time stamp: %s", os.date("%c", tstamp))) end status, bufrlres = comm.exchange(host, port, rlreq, {proto=port.protocol, timeout=TIMEOUT}) if status then -- This only looks at the first fragment of what can possibly be several -- fragments in the response. local _, data, k, q, v -- Skip the first 10 bytes of the header, then get the data which is -- preceded by a 2-byte length. _, data = bin.unpack(">P", bufrlres, 11) -- This parsing is not quite right with respect to quoted strings. -- Backslash escapes should be interpreted inside strings and commas should -- be allowed inside them. for k, q, v in string.gmatch(data, "%s*(%w+)=(\"?)([^,\"]*)%2,?") do if DEFAULT_FIELDS[k] or nmap.verbosity() then table.insert(output, string.format("%s: %s", k, v)) end end end if(#output > 0) then nmap.set_port_state(host, port, "open") return stdnse.format_output(true, output) else return nil end end