portrange

Port range, often written as portrange, refers to a contiguous set of port numbers used in networking. A port range defines which destination or source ports are to be matched or allocated, typically in firewall rules, network address translation, or service configuration. Port numbers span from 0 to 65535 and are divided into well-known ports (0–1023), registered ports (1024–49151), and dynamic/private ports (49152–65535). The range concept allows policies or configurations to apply to multiple ports at once and to designate groups of adjacent ports used by certain services or applications. The value 0 is reserved on many systems and is usually not used for valid transport connections, while 65535 is the maximum port number.

Notation and usage: A portrange is commonly written as a start-end pair, for example 80-89 or 1000-2000. Some tools accept alternative notations such as start:end. When configuring networking devices like firewalls, NATs, or load balancers, port ranges can simplify rule sets by covering multiple ports with a single entry. They are useful for services that operate on several related ports or for accommodating dynamic port allocation within a defined band.

Security and best practices: Use the smallest practical range needed to support a service, and document the rationale for the chosen range. Regularly review and adjust ranges as services evolve. Misconfigured portranges can expose unnecessary ports, create routing or filtering gaps, or complicate troubleshooting. Proper management of port ranges helps balance functionality with security and operational clarity.