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

2009-10-20 I noticed requests for port 37/udp in ou ... 9 years ago
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.

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