How to use it
- Type a port number such as 443, or a service name such as https, into Port or service name.
- Read Service and Port range. When several entries use the port, the Matching entries table lists them all.
- Check Protocols in the table, since TCP and UDP can have different entries for the same number.
The three port ranges
RFC 6335 section 6 divides the 16-bit port numbers of TCP, UDP, SCTP and DCCP into three ranges. The system ports, also called well-known ports, are 0 to 1023 and are assigned by IANA. The user ports, also called registered ports, are 1024 to 49151, also assigned by IANA. The dynamic ports, also called private or ephemeral ports, are 49152 to 65535 and are never assigned.
- System (well-known) 0 to 1023: assigned by IANA. Common services such as https on 443 are here.
- User (registered) 1024 to 49151: assigned by IANA, for many applications and products.
- Dynamic (private or ephemeral) 49152 to 65535: never assigned, so the registry has no entry for these ports.
What an entry means
An entry records that a service name is assigned to a port number for one or more transport protocols, such as TCP and UDP. It does not show that the service runs there: the registry records the assignment, and a program may still use the same port for something else. A name can be on a range of ports, as x11 is on 6000 to 6063.
Where the list comes from
The list is the IANA Service Name and Transport Protocol Port Number Registry as retrieved on 10 November 2026. Reserved and unassigned rows are left out, and a TCP row and a UDP row with the same name and port are shown as one entry with both protocols. Many entries carry no reference at all, and the page then says so.
Worked example: port 443
Port 443 has one entry in the registry, https, assigned for tcp, sctp and udp. It is a system port, because it is below 1024. The entry says http protocol over TLS/SSL, and its reference is RFC 9110.
Typing https gives the same entry, and the table below shows the outputs for 443.
| Output | For 443 |
|---|---|
| Service | https on port 443 (tcp, sctp, udp) |
| Port range | System (well-known) port, 0 to 1023: assigned by IANA (RFC 6335, section 6). |
| Description | http protocol over TLS/SSL |
| Reference | RFC 9110 |
Frequently asked questions
Why does the registry list a port for a service I do not run?
The registry records assignments, and an entry can stay listed after a service stops being used. Being listed does not mean anything is running on the port on your machine.
Which range do the ports of a web server belong to?
Ports 80 and 443 are system ports, from 0 to 1023. The registry lists them as http and https. A web server can use other ports as well, and the registry does not force a choice.
What is the difference between TCP and UDP ports?
TCP and UDP have their own port numbers. The same number can have one entry for TCP and another for UDP, or both, and the table shows the protocols of each entry. Domain names, for example, use port 53 on both.
Why is there no entry for a port between 49152 and 65535?
RFC 6335 section 6 says the dynamic ports are never assigned. Operating systems use them for temporary connections that they open themselves, so the registry has no entry for them.
Can I use a port that the registry does not list?
Yes, if your software and your firewall allow it. A port without an entry is not reserved by the registry, but another program on your machine may already be using it.
Is my search sent anywhere?
No. The lookup runs in your browser against the list stored with the page, and nothing you type is sent to our server or stored there.
Sources
- IANA Service Name and Transport Protocol Port Number Registry
- RFC 6335: Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry
Figures and text last checked on Tuesday, November 10, 2026.