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Different between port 123 (ntp) and 37 (timeserver)

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Richard Pereira_1
Regular Advisor

Different between port 123 (ntp) and 37 (timeserver)

My security team is scanning our hosts and wants a justification for the use of port 37. I'm a bit confused. The hosts are all xntpd clients so I'm assuming they would be using port 123. However, I do get a response on port 37. What is port 37 used for exactly?
Honored Contributor

Re: Different between port 123 (ntp) and 37 (timeserver)

Bonjour Richard,

There is no direct relation between ntp and time. time is a protocol included in a set called "tcp small services". You can comment it in /etc/inetd.conf.

More details, see

Esteemed Contributor

Re: Different between port 123 (ntp) and 37 (timeserver)

Bill Hassell
Honored Contributor

Re: Different between port 123 (ntp) and 37 (timeserver)

Port 37 has been obsolete for a very long time and is one of the many archaic ports that should be disabled. NTP does not use 37 at all, only port 123. I would disable the following services in inetd.conf immediately, even if the security team has not reported them:


Bill Hassell, sysadmin
Valued Contributor

Re: Different between port 123 (ntp) and 37 (timeserver)

TIME protocol's purpose is to provide a site-independent, machine readable date and time.

TIME can operate over either TCP or UDP. When operating over TCP, a host connects to a server that supports the TIME protocol on TCP port 37. The server then sends the time as a 32-bit unsigned binary number in network byte order representing a number of seconds since 00:00 (midnight) 1 January, 1900 GMT and closes the connection. The host receives the time and closes the connection.

When operating over UDP, the client sends a (typically empty) datagram to UDP port 37. The server responds with a single datagram of length 4 containing the time. There is no connection setup or teardown.

The TIME protocol has been superseded by the Network Time Protocol (NTP).

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