Port 13
Daytime Protocol
The Daytime Protocol is a simple network service defined in RFC 867 that provides the current date and time information to requesting clients. Operating on TCP and UDP port 13, it was historically used for testing, troubleshooting, and basic time synchronization before more precise protocols emerged..
Technical Details
The Daytime Protocol, specified in RFC 867, is one of the earliest Internet services designed to provide a human-readable string representing the current date and time. It is a text-based service that listens on port 13 over both TCP and UDP. When a client establishes a connection or sends a datagram to the server, the server responds with an ASCII string containing the current date and time and then closes the connection.
This protocol is extremely lightweight, has no authentication, and provides no formatting guarantees beyond a general description in RFC 867. The typical response may vary among implementations, including differences in time zone representations or string formats.
Due to its simplicity, the Daytime Protocol was primarily used for benchmarking, testing network reachability, and basic time queries during early Internet development. Today, it has largely been superseded by protocols such as NTP (Network Time Protocol) and SNTP, which provide precise, secure time synchronization.