Port 13Daytime 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..
- transport
- tcp · udp
- in transit
- cleartext
- assignment
- official
- risk
- 2/10
- lookups
- 8,289
2 transports registered
payload readable on path
registered with iana
safe
rank 604 of 993 · top 61%
Technical Details
what runs on :13The 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 Today, it has largely been superseded by protocols such as NTP (Network Time Protocol) and SNTP, which provide precise, secure time synchronization.
Security Information
exposure of :13risk score
2/ 10safe
routine exposure. this port is rarely the way in on its own — keep it patched and logged and move on.
network services averages 3.9 across 604 ports — this one sits 1.9 below.
in transit
cleartext
credentials and payloads are readable by anyone on path
assignment
official
registered with iana for this service — scanners fingerprint it by number
reachable over
tcp · udp
udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite
security overview
Vulnerabilities:
- Because the Daytime Protocol lacks authentication and encryption, its responses can be spoofed, leading to potential confusion or misuse.
- It can be leveraged in amplification attacks within DDoS scenarios, where the attacker sends small queries with a spoofed victim’s IP address, causing the server’s larger responses to target the victim.
- The protocol can inadvertently disclose system information if the server’s date/time format reveals sensitive details.
Mitigations:
- Disable the Daytime service unless explicitly required, as it is rarely used in modern environments.
- Employ firewall rules to restrict or block inbound and outbound traffic on port 13.
- Use more secure, authenticated time synchronization protocols like NTP with authentication.
- Monitor network traffic for unusual usage of port 13 to detect possible misuse or scanning activity.
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risk mix of the 8 listed
- caution100%
0 of 8 encrypted