UDPport

UDPPort refers to the 16-bit port number used by the User Datagram Protocol (UDP) to identify the source and destination applications on a host. UDP ports allow multiple applications to concurrently receive datagrams sent to the same host, providing a simple multiplexing mechanism at the transport layer. The port space ranges from 0 to 65535; port 0 is reserved and typically not used for normal communication.

Ports are categorized by their typical usage. Well-known ports (0–1023) are commonly assigned to standard services, registered ports (1024–49151) are assigned for specific applications, and dynamic or private ports (49152–65535) are often used for ephemeral client-side endpoints. A host may listen on a specific port to receive UDP datagrams for a particular service, or send from an ephemeral port for outbound communication.

A UDP header is 8 bytes and contains the source port, destination port, length, and checksum fields. The checksum covers a UDP pseudo-header that includes the IP addresses and protocol, providing a basic integrity check for datagrams. UDP itself is connectionless and does not establish a persistent session or guarantee delivery, ordering, or avoidance of duplicates. Applications using UDP can implement their own reliability or tolerate datagram loss depending on requirements.

Common uses and implications. Many core services rely on UDP, such as DNS (port 53), NTP (port 123), DHCP (ports 67 and 68), and TFTP (port 69). Because UDP is stateless, network devices and firewalls often manage UDP traffic with specific rules, rate limiting, or NAT translations. UDPPort remains the fundamental endpoint identifier for routing and delivering UDP datagrams to the correct application process.