What this tool does
This tool searches the IANA Service Name and Transport Protocol Port Number Registry — the same registry operating systems, firewalls, and network tools ultimately draw from when they show a service name for a port. It's client-side: search more than 6,100 port numbers and 12,500 protocol-specific IANA records. The dataset is loaded only when needed and searches then run entirely in your browser, with nothing sent anywhere. Search by an exact port number (optionally with /tcp or /udp, e.g. 443/tcp) or by a service name or keyword, and a curated set of security notes for commonly attacked or unencrypted ports.
Common TCP and UDP port numbers
A small number of ports account for most real-world lookups. Here are the ones worth knowing by name, with a dedicated reference page for each:
| Port | Service | Protocol | Typical use |
|---|---|---|---|
| 22 | SSH | TCP | Secure remote command-line access to servers and network devices, and… |
| 23 | Telnet | TCP | Legacy remote terminal access. Largely obsolete for general use, but… |
| 25 | SMTP | TCP | Server-to-server email transfer between mail servers. Not typically… |
| 53 | DNS | TCP/UDP | Domain name resolution — translating hostnames to IP addresses. UDP… |
| 80 | HTTP | TCP | Unencrypted web traffic. Increasingly used mainly to redirect to… |
| 110 | POP3 | TCP | Downloading email from a mail server to a single client, typically… |
| 143 | IMAP | TCP | End-user email retrieval with server-side folder state, letting… |
| 443 | HTTPS | TCP/UDP | Encrypted web traffic — the standard port for essentially all… |
| 445 | SMB | TCP | Windows file and printer sharing, plus related services like Active… |
| 1433 | Microsoft SQL Server | TCP | Default listener port for Microsoft SQL Server database connections… |
| 3306 | MySQL | TCP | Default listener port for MySQL and MariaDB database connections from… |
| 3389 | RDP | TCP/UDP | Remote Desktop Protocol — full graphical remote control of a… |
| 5432 | PostgreSQL | TCP | Default listener port for PostgreSQL database connections from… |
| 6379 | Redis | TCP | Default listener port for Redis, an in-memory key-value data store… |
| 8080 | HTTP Alternate | TCP | A very common alternate HTTP port — used for development servers… |
| 27017 | MongoDB | TCP | Default listener port for MongoDB, a document-oriented NoSQL database. |
Common ports can be grouped into several broad categories by common use: remote administration (SSH on 22, RDP on 3389, Telnet on 23), web traffic (HTTP on 80, HTTPS on 443, alternate HTTP on 8080), email (SMTP on 25, POP3 on 110, IMAP on 143), databases (MySQL on 3306, PostgreSQL on 5432, Microsoft SQL Server on 1433, MongoDB on 27017, Redis on 6379), and Windows file sharing (SMB on 445), one of the most consistently targeted ports for ransomware lateral movement. Each has its own reference page above with usage, encryption, and firewall-exposure notes specific to that port.
Port ranges, briefly
RFC 6335 divides the full 0–65535 port space into three ranges. Well-known / System ports (0–1023) are the oldest and most tightly controlled — historically requiring root/administrator privileges to bind on Unix-like systems, and covering most of the protocols people search for by name (HTTP, SSH, DNS, SMTP). Registered / User ports (1024–49151) cover everything from major databases (PostgreSQL, MySQL) to countless smaller applications; assignment here is still first-come-first-served through IANA but far less strict. Dynamic / Private ports (49152–65535) never receive permanent IANA assignments — this range is intended for dynamic/private use and is commonly used for ephemeral connections (e.g. the client side of an outgoing HTTP request), and any two people running unrelated software on ports in this range at different times is completely normal and expected.
About the security notes
A small number of results on this page carry an additional security note, separate from the official IANA description — these are this tool's own editorial annotations, not part of the registry itself. IANA's registry explicitly disclaims any such judgment: assignment of a port number doesn't imply endorsement, and traffic on a registered port isn't necessarily "good" traffic. The notes here are reserved for genuinely well-established cases — protocols with no encryption by design (like Telnet or FTP), or services repeatedly documented as frequent targets or found exposed-without-authentication in real incidents and internet-wide scans (like RDP or Redis) — not a general risk rating for every port.
Frequently asked questions
Why does a search show multiple entries for the same port?
Some ports have more than one registered service name — sometimes because a newer name replaced an older one that's kept for historical reference, sometimes because the same port genuinely serves related-but-distinct purposes (for example, port 80 lists both http and an explicitly-marked-duplicate www entry). Every entry shown here comes directly from the registry.
I searched a port and got nothing. Does that mean it's not in use?
Not necessarily — it means this tool's dataset has no registered service name for it. Plenty of real, widely-used software runs on ports with no confirmed IANA registration at all — it's simply not required for a service to work. This dataset is generated directly from IANA's official registry and verified against its source hash on every build (see the methodology note below), so a missing entry here genuinely reflects an absence in the registry itself, not a gap in how current this tool's data is.
Does an unassigned port mean it's safe to use for my own service?
Practically, often yes for private/internal use — but it isn't a permanent guarantee, since IANA can assign a currently-unassigned port to something new at any time. This is different from a port marked Reserved, which IANA has explicitly set aside for a specific reason rather than simply not yet assigned — a Reserved port generally isn't a good choice for your own service, since it may be reserved precisely because it's intended for a specific future or protocol-level use. What you should not do with either is pick a specific number in the dynamic/private range (49152–65535) as a fixed identifier for your service — RFC 6335 makes clear this range doesn't receive permanent IANA assignments and exists for dynamic/private use, commonly drawn on for ephemeral, short-lived connections, though the exact range an implementation uses for this can vary. That range solves a different problem (avoiding IANA-registered-port collisions for transient connections) than the one a fixed, memorable port number for your own service needs solved.
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
Last reviewed: . Data source: IANA Service Name and Transport Protocol Port Number Registry. The bundled dataset is generated directly from the official IANA CSV and verified against its source hash. Last registry update: August 11, 2026. The security notes are this tool's own editorial annotations, kept structurally separate from the IANA data itself and applied only to ports with well-established, sourced justification — not a general risk score.