I noticed requests for port 37/udp in ou ... / 2009-10-20

2009-10-20 I noticed requests for port 37/udp in ou ...
I noticed requests for port 37/udp in our firewall to our ntp server. That is the 'daytime' protocol which is absolutely ancient in an Internet timescale. I opened the port and started the service as an experiment and started tcpdump on it. The results are interesting:
09:50:09.749723 IP xx.xx.178.51.37 > 131.211.84.189.123: NTPv4 client, strat 2, poll 7, prec -20
09:50:09.749782 IP 131.211.84.189.123 > xx.xx.178.51.37: NTPv4 server, strat 2, poll 7, prec -19
09:52:19.808243 IP xx.xx.178.51.37 > 131.211.84.189.123: NTPv4 client, strat 3, poll 7, prec -20
09:52:19.808301 IP 131.211.84.189.123 > xx.xx.178.51.37: NTPv4 server, strat 2, poll 7, prec -19
09:53:08.511939 IP xx.xxx.183.183.34505 > 131.211.84.189.37: UDP, length: 0
09:53:08.513364 IP 131.211.84.189.37 > xx.xxx.183.183.34505: UDP, length: 4
Most traffic seen by 'tcpdump port 37' is from source port 37. Which is an artifact of certain NAT devices translating privileged ports (< 1024) to other privileged ports. Certain versions ntpd seem to ignore these requests. But there are real clients using the 'daytime' protocol.

Tags: , ,

IPv6 check

Running test...
, reachable as koos+website@idefix.net. PGP encrypted e-mail preferred. PGP key 5BA9 368B E6F3 34E4 local copy PGP key 5BA9 368B E6F3 34E4 via keyservers

RSS
Meningen zijn die van mezelf, wat ik schrijf is beschermd door auteursrecht. Sommige publicaties bevatten een expliciete vermelding dat ze ongevraagd gedeeld mogen worden.
My opinions are my own, what I write is protected by copyrights. Some publications contain an explicit license statement which allows sharing without asking permission.
Other webprojects: Camp Wireless, wireless Internet access at campsites, The Virtual Bookcase, book reviews
This page generated by $Id: newsitem.cgi,v 1.55 2021/11/09 13:09:49 koos Exp $ in 0.005098 seconds.