Common Ports Reference

Frequently asked questions

What is a well-known port?

A well-known port is a number in the range 0 to 1023 that IANA reserves for a specific, widely used service, such as 80 for HTTP or 22 for SSH. Because these assignments are standardized, a client can connect to a service on its default port without any prior negotiation. On many systems, binding to a well-known port requires administrator or root privileges.

What is the difference between TCP and UDP?

TCP and UDP are the two main transport protocols that sit on top of IP. TCP is connection oriented and reliable: it sets up a connection, orders the data, and retransmits anything lost, which suits web pages, email, and file transfer. UDP is connectionless and has no built-in delivery guarantee, which makes it lighter and faster for things like DNS lookups, video streaming, and voice calls. Some services, such as DNS, are assigned both.

What port does HTTPS use?

HTTPS uses TCP port 443 by default, while plain HTTP uses TCP port 80. When you type a URL without a port, the browser assumes 443 for https and 80 for http, so you rarely need to write the number yourself. A server can be configured to serve HTTPS on a different port, in which case the URL must include it, for example https://example.com:8443.

Which ports do databases use?

Common defaults are 3306 for MySQL and MariaDB, 5432 for PostgreSQL, 6379 for Redis, 27017 for MongoDB, 1433 for Microsoft SQL Server, and 1521 for Oracle. These are conventions rather than hard rules, and production deployments often change them. Database ports should almost never be exposed directly to the public internet; keep them behind a private network or a firewall.

What are ports 0-1023 versus 1024-49151?

Ports split into three ranges. 0 to 1023 are the well-known or system ports, reserved for core services and usually requiring elevated privileges to bind. 1024 to 49151 are the registered ports, which IANA assigns to specific applications on request. 49152 to 65535 are the dynamic or ephemeral ports, which the operating system hands out temporarily for the client side of a connection.

Can I change which port a service uses?

Yes. Port numbers are conventions, not fixed hardware addresses, so almost any service can be configured to listen on a different port. Running SSH on a non-standard port or a web server on 8080 is common. The trade-off is that clients must then be told the new port, since they will otherwise assume the default, so document any change clearly.

Does this tool send the ports I search to a server?

No. The full list of ports is embedded in the page, and all filtering happens in your browser with JavaScript. You can confirm this by opening DevTools and watching the Network tab: typing in the search box makes zero requests.