--- title: Before NTP there were Time and Daytime | daily.dev description: Exploring the history behind NTP's predecessors, the Time Protocol (RFC 868) and Daytime Protocol (RFC 867) from the early 1980s, both shepherded by Jon... canonical: https://daily.dev/posts/before-ntp-there-were-time-and-daytime-onwof2jqj twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Before NTP there were Time and Daytime | daily.dev og:description: Exploring the history behind NTP's predecessors, the Time Protocol (RFC 868) and Daytime Protocol (RFC 867) from the early 1980s, both shepherded by Jon... og:url: https://daily.dev/posts/before-ntp-there-were-time-and-daytime-onwof2jqj og:image: https://api.daily.dev/og/posts/OnWoF2jQJ.png og:image:alt: Before NTP there were Time and Daytime og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Before NTP there were Time and Daytime **[Jeff Geerling](https://daily.dev/sources/jeffgeerling)** · 6 min read · 2 upvotes · 1 comments ## Summary Exploring the history behind NTP's predecessors, the Time Protocol (RFC 868) and Daytime Protocol (RFC 867) from the early 1980s, both shepherded by Jon Postel. These simple protocols returned time as a 32-bit binary number or human-readable string over ports 37 and 13, with limitations like 1-second resolution, no delay compensation, and a 2036 rollover bug similar to Y2K38. NIST still runs these legacy services on time.nist.gov with a customized, non-standard response format. Includes step-by-step instructions for running a Time/Daytime server on Linux using xinetd, built for an easter-egg demo at VCF Midwest featuring vintage Macs. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What is the Y2K36 bug in the Time Protocol (RFC 868)? It's a rollover bug where the Time Protocol's 32-bit integer, counting seconds since midnight January 1, 1900 GMT, runs out of range on February 7, 2036. This is analogous to the Unix Y2K38 problem. NTP shares the same underlying 32-bit seconds field but avoids the issue by using 'Eras' to extend its effective range beyond that date. _Track protocol quirks like this on daily.dev before a legacy timestamp field bites you in production._ ### How do I set up a Time or Daytime server on Debian or Raspberry Pi OS? Install xinetd with apt, then enable the built-in time and daytime service definitions in /etc/xinetd.d/time and /etc/xinetd.d/daytime by setting 'disable' to 'no' for both tcp and udp, and restart xinetd. Open ports 37 (Time) and 13 (Daytime) on the firewall, then test with netcat from another machine on the network. _Developers reviving old protocols for retro networking projects can compare setup notes on daily.dev._ ### Does NIST still run the old RFC 867/868 Daytime protocol service? Yes, NIST still operates a Daytime protocol service on time.nist.gov, port 13. It returns a custom format that matches neither original RFC 867 nor 868 syntax, structured as Modified Julian Date, year-month-day, time, and an 'on-time marker' plus UTC(NIST) label, originally more meaningful in older telephone-based ACTS time systems. _Curious developers can dig deeper into legacy internet infrastructure quirks like this on daily.dev._ ## Community discussion Top comments from developers on daily.dev. **@rvrlx** · 0 upvotes > Neat deep-dive into the pre-NTP era. Interestingly, according to NIST's docs, the Time protocol is used by only 1%-2% of its customers. While the Daytime protocol "is widely used by small computers and dedicated hardware systems running MS-DOS and similar operating systems". Source: [NIST. ](https://www.nist.gov/pml/time-and-frequency-division/time-distribution/internet-time-service-its#daytime-protocol-rfc-867)I wonder what the Daytime percentage is? ## Similar posts on daily.dev - [Welcome to the home of the Network Time Protocol \(NTP\) Project.](https://daily.dev/posts/welcome-to-the-home-of-the-network-time-protocol-ntp-project--ox0k0u0vs) · Hacker News · 1 upvotes · 0 comments --- Tags: [#linux](https://daily.dev/tags/linux), [#networking](https://daily.dev/tags/networking) [View this post on daily.dev](https://daily.dev/posts/before-ntp-there-were-time-and-daytime-onwof2jqj) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Before NTP there were Time and Daytime","url":"https://daily.dev/posts/before-ntp-there-were-time-and-daytime-onwof2jqj","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/before-ntp-there-were-time-and-daytime-onwof2jqj"},"datePublished":"2026-08-30T22:13:48.219Z","dateModified":"2026-09-14T06:33:05.982Z","description":"Exploring the history behind NTP's predecessors, the Time Protocol (RFC 868) and Daytime Protocol (RFC 867) from the early 1980s, both shepherded by Jon...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/b56116a1b8fbee9c40f3010b94c01fd2?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/b56116a1b8fbee9c40f3010b94c01fd2?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Jeff Geerling","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Jeff Geerling","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/a425a8edd27a4930ae183c796db840b9","url":"https://daily.dev/sources/jeffgeerling"},"commentCount":1,"discussionUrl":"https://daily.dev/posts/before-ntp-there-were-time-and-daytime-onwof2jqj","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":2},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":1}],"keywords":"linux,networking","timeRequired":"PT6M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Jeff Geerling","item":"https://daily.dev/sources/jeffgeerling"},{"@type":"ListItem","position":3,"name":"Before NTP there were Time and Daytime"}]} {"@context":"https://schema.org","@type":"WebPage","@id":"https://daily.dev/posts/before-ntp-there-were-time-and-daytime-onwof2jqj","comment":[{"@type":"Comment","text":"Neat deep-dive into the pre-NTP era. Interestingly, according to NIST’s docs, the Time protocol is used by only 1%-2% of its customers. While the Daytime protocol “is widely used by small computers and dedicated hardware systems running MS-DOS and similar operating systems”. Source: NIST. I wonder what the Daytime percentage is?","datePublished":"2026-08-31T09:05:00.916Z","url":"https://daily.dev/posts/OnWoF2jQJ#c-vd3A2veIq","author":{"@type":"Person","name":"Rudi van Rooyen","url":"https://daily.dev/rvrlx","image":"https://lh3.googleusercontent.com/a/AATXAJzM6gKu99mFV33CEzyMV2C_mteeqteo8e8p8EaR=s100"}}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/before-ntp-there-were-time-and-daytime-onwof2jqj#faq","mainEntity":[{"@type":"Question","name":"What is the Y2K36 bug in the Time Protocol (RFC 868)?","acceptedAnswer":{"@type":"Answer","text":"It's a rollover bug where the Time Protocol's 32-bit integer, counting seconds since midnight January 1, 1900 GMT, runs out of range on February 7, 2036. This is analogous to the Unix Y2K38 problem. NTP shares the same underlying 32-bit seconds field but avoids the issue by using 'Eras' to extend its effective range beyond that date. Track protocol quirks like this on daily.dev before a legacy timestamp field bites you in production."}},{"@type":"Question","name":"How do I set up a Time or Daytime server on Debian or Raspberry Pi OS?","acceptedAnswer":{"@type":"Answer","text":"Install xinetd with apt, then enable the built-in time and daytime service definitions in /etc/xinetd.d/time and /etc/xinetd.d/daytime by setting 'disable' to 'no' for both tcp and udp, and restart xinetd. Open ports 37 (Time) and 13 (Daytime) on the firewall, then test with netcat from another machine on the network. Developers reviving old protocols for retro networking projects can compare setup notes on daily.dev."}},{"@type":"Question","name":"Does NIST still run the old RFC 867/868 Daytime protocol service?","acceptedAnswer":{"@type":"Answer","text":"Yes, NIST still operates a Daytime protocol service on time.nist.gov, port 13. It returns a custom format that matches neither original RFC 867 nor 868 syntax, structured as Modified Julian Date, year-month-day, time, and an 'on-time marker' plus UTC(NIST) label, originally more meaningful in older telephone-based ACTS time systems. Curious developers can dig deeper into legacy internet infrastructure quirks like this on daily.dev."}}]} ```