The Time Protocol — a 32-bit seconds-since-1900 count, returned as four raw bytes.
RFC 868 defines Time as a machine-readable counterpart to Daytime: connect, and the server returns a 32-bit big-endian count of seconds since 1 January 1900 UTC, then closes. NIST still answers on time.nist.gov and reports that only about 2% of its Internet Time Service traffic uses it, while urging users to move to NTP. The protocol has no authentication, no round-trip correction, and one-second resolution, and its 32-bit counter rolls over in 2036. It was an inetd built-in on classic UNIX and is off by default now.
Expose with care
Only defensible as a deliberate public time service; the UDP form is spoofable and reflectable, and NTP replaces it for actually setting a clock.
$ nc -w 5 time.nist.gov 37 | xxdSeen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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