In constructing an NTP time demo on previous Macs for VCF Midwest, I got here throughout RFC 867 and RFC 868, for the ‘Daytime’ and ‘Time’ Protocols, respectively.
My first publicity to any type of community time was once I upgraded from a used PowerBook 180c to my first ‘new’ pc, a Energy Mac G3, in 2000. With the introduction of Mac OS 8.5, Apple added a ‘Community Time Server’ choice within the Date & Time Management Panel.
I bear in mind dialing up the Web by way of PPP, then clicking the ‘Set Time Now’ button, and seeing my pc’s clock replace. I did not assume a lot of it on the time, however this was far more than setting my wristwatch utilizing the ‘Time and Temperature’ cellphone line, which was beforehand essentially the most exact time supply I might entry usually.
However previous to NTP (RFC 1059 in 1988), there was a way more casual approach of requesting time from a distant server. With the Time Protocol (RFC 868), a time request was so simple as:
Open a connection to the server on port 37 (TCP join, or ship an empty UDP datagram)Obtain the time as a 32-bit binary quantity
That is it!
Within the mid-80s, this was an especially environment friendly technique of time switch, which was useful since community bytes have been treasured, and also you did not want a posh routine to deal with the 32-bit time.
However there are downsides to this simplistic strategy. Particularly in case you have been routing the request by means of the Web, with a number of non-deterministic hops:
The 32-bit quantity was simply “seconds since 00:00 (midnight) 1 January 1900
GMT”, so the most effective timing decision you would ever get is 1 second (NTP provides 64-bit decision, which may scale previous microseconds).There isn’t any timestamping of the particular request or response, so there is no approach to account for community delays, or common them out over time.The 32-bit integer worth will run out on February 7, 2036, leading to a ‘Y2K36’ bug just like the Unix Y2K38 Epochalypse. (NTP has the identical drawback however launched Eras to take care of it.)
However in 1983, when the RFC was launched, it was only a handy approach for a pc on a community to get time from a server with a steady clock (many computer systems did not have a real-time clock). It wasn’t used for essential companies like distributed databases, particularly since timing decision past 1 second wasn’t that widespread in computing (assuming you even had a world clock!).
The Daytime protocol (RFC 867) is succinct, however ambiguous. It defines a protocol by which a complete day and timestamp may be returned in human-readable output, for instance:
The anomaly comes with the format, which is left to the implementor:
There isn’t any particular syntax for the daytime. It is strongly recommended that
it’s restricted to the ASCII printing characters, area, carriage
return, and line feed. The daytime needs to be only one line.
One standard syntax is:
Weekday, Month Day, Yr Time-Zone
Instance:
Tuesday, February 22, 1982 17:37:43-PST
Instantly following, it suggests the choice dd mmm yy hh:mm:ss zzz, which was used for SMTP!
Enjoyable truth: NIST nonetheless runs RFC 867/868 Daytime companies on time.nist.gov!
61281 26-08-29 23:31:43 50 0 0 771.1 UTC(NIST) *
That is utilizing a custom-made response that matches neither of the RFC codecs:
The place JJJJJ is the Modified Julian Date, and the OTM is an ‘on-time marker’, which marks that the time needs to be appropriate the second you obtain it… however from my analysis is extra of a ‘finest guess’ that was extra helpful in older phone time programs, which have been in some methods extra deterministic.
NIST’s is certainly one of many stranger time codecs I’ve seen!
The Time and Daytime Protocols have been each shepherded by Jon Postel, a.ok.a. the ‘God of the Web’, recognized for different hits like SMTP, IANA, and Postel’s legislation.
I usually marvel what it was prefer to be on the bottom flooring when these protocols and companies have been written. I used to be extra anxious about getting time on my household’s Nintendo. Not that my toddler mind might’ve comprehended community time switch again then!
Run your individual Time and Daytime Server
After taking a pleasant lengthy detour studying about Time and Daytime, I made a decision I’d add some easter eggs at my sales space at VCF Midwest—one in all them being Time/Daytime companies on ports 37 and 13, respectively.
If you wish to run your individual Time/Daytime server, it is simple in Linux—they’re constructed into xinetd. These directions are for Pi OS / Debian, nevertheless it’s related on different distros:
sudo apt set up xinetd
sudo systemctl allow xinetd
# Edit time and daytime configurations
sudo nano /and so on/xinetd.d/time
-> service time tcp set disable to “no”
-> service time udp set disable to “no”
sudo nano /and so on/xinetd.d/daytime
-> service daytime tcp set disable to “no”
-> service daytime udp set disable to “no”
# Restart xinetd
sudo systemctl restart xinetd
Make sure that ports 37 and 13 are open in your firewall, then from one other pc on the community:
$ nc 10.0.37.60 37 | xxd –g 1
00000000: ee 3f 24 b3 .?$.
# Confirm the Time worth by passing it into `date`:
$ date –r $(( 0xee3f24c8 – 2208988800 ))
Solar Aug 30 16:53:12 CDT 2026
# Daytime
$ nc –v 10.0.37.60 13
Connection to 10.0.37.60 port 13 [tcp/daytime] succeeded!
30 AUG 2026 16:49:26 CDT
The 2208988800 within the date translation command above is the distinction (in seconds) between 1900 and 1970, required as a result of UNIX time’s epoch is in 1970 (versus 1900 for Time and NTP).
In the event you’ll be at VCF Midwest—particularly in case you have a classic pc with Networking hooked up to the present’s community—I can provide you a great Time. Or Daytime, for that matter!
