Searching the Port Registry
Port Number Lookup searches registered service names and their associated transport ports. Enter a number such as 443 to see matching records, or enter a service name such as ssh. A result describes the registry assignment; it does not contact a device or test a connection to that port.
The form also accepts a range of up to 1,024 ports and up to 20 values separated by commas. For example, 20-25 searches a short range, while 22,80,443 searches selected values. Use a smaller selection when you need a readable set of records rather than every assignment in a large part of the registry.
Choose a transport protocol to narrow the results. All protocols includes TCP, UDP, SCTP, and DCCP where matching records exist. The common ports menu fills the search field with a selected number; submit the form to run that search. Existing query values remain visible so that the result can be checked against the input.
Understanding the Records
Each record identifies a port or port range, a transport protocol, and the service name supplied by IANA. The registry description provides additional context when available. Some entries have no service name because they are reserved, unassigned, or deregistered. Those states are not interchangeable with a registered service.
A single port number can have several records. Read the protocol next to each number: a TCP assignment does not automatically describe the same application behavior over UDP. Alternative names can also appear for one service. Where the registry identifies an alternative record, the result explains that relationship.
The classification for a single number shows the category containing that port. System ports run from 0 through 1023, user ports from 1024 through 49151, and dynamic or private ports from 49152 through 65535. Classification describes the number range, not the current security or accessibility of a network service.
Using a Result in Network Configuration
A registered port is a useful starting point when checking an application setting or a firewall rule. Compare the result with the actual configuration of the service you administer. Software can listen on a different port, and a port forwarding rule can use different external and internal port numbers.
Common-use notes explain selected services without replacing the underlying registry data. A familiar description is not evidence that the named application is running on a particular address. Traffic using a registered number can belong to another application, and an application can use a port without being the registered service.
Use Open Port Checker when the question is whether a particular public address accepts a TCP connection. This registry lookup and a connection test answer different questions. Neither an assigned service name nor an empty registry result establishes that a port is open, closed, safe, or unsafe.
Result Pages and Registry Dates
Large searches are divided into result pages. Previous Results and Next Results move through the matching records while keeping the search and protocol filter. When pagination is present, the copy action includes only the records displayed on the current page, along with the registry version.
The registry version identifies the dataset used for the lookup. It is not a test timestamp and does not mean the target service was inspected on that date. If an application has recently changed its registered information, check the dataset date before assuming an older description is still current.
No matching records means that the search did not find a service assignment in this dataset. For an individual number, its classification can still be shown. If the registry is temporarily unavailable, the page reports that problem separately rather than presenting the failure as an empty search.
