Port Number Lookup
Find the service behind a port — or the port a service uses
Type a port number (e.g. 443) to see what runs on it, or type a service name or keyword
(e.g. ssh, database, backup) to find the ports it uses.
Every result includes the typical use, the protocols (TCP/UDP), the port range and practical
security considerations.
Browse the port table
Filter the full reference table by protocol, range or risk. Click any row to load it in the search above.
| Port | Service | Also known as | Protocols | Range | Risk |
|---|
How ports work
Port ranges
Every TCP/UDP socket is identified by a port number from 0 to 65535. The IANA divides these into three ranges:
| Range | Ports | Meaning |
|---|---|---|
| Well-known | 0 – 1023 | Reserved for standard, system-level services (HTTP, DNS, SSH). On Unix these require root/admin to bind. |
| Registered | 1024 – 49151 | Assigned to specific applications by IANA (databases, message brokers, app servers). Often the ports you configure yourself. |
| Dynamic / ephemeral | 49152 – 65535 | Used by clients for outbound connections. Not services — you should not open these inbound. |
TCP vs UDP
TCP is a reliable, connection-oriented protocol: it guarantees delivery, orders packets and retransmits lost ones. Most services (web, mail, databases) use TCP. UDP is connectionless and faster but does not guarantee delivery — it is used where speed matters more than perfect reliability (DNS queries, NTP, VoIP, streaming). Many services listen on both.
Security: the golden rules
- Minimise exposure. Only open the ports a service truly needs, and only to the sources that need them.
- Never expose databases or admin consoles (MySQL, PostgreSQL, Redis, Elasticsearch, Kibana, Docker, Kubernetes) to the internet.
- Prefer encrypted protocols — HTTPS over HTTP, SSH over Telnet, LDAPS over LDAP, IMAPS/POP3S over plain mail.
- Use strong authentication (keys over passwords) and rate-limit / ban brute-force attempts on SSH, RDP and similar.
- Keep software patched — many of the most-attacked ports (445/SMB, 3389/RDP, 22/SSH) are targeted because of unpatched services.
- Block legacy, cleartext protocols (Telnet, rsh/rlogin, plain FTP, NetBIOS) unless you have a specific reason.
About this reference
This table covers the most commonly referenced and operationally important ports. If you type a port number that is not individually listed, the tool still tells you which range it belongs to and whether it is a well-known service. Port assignments come from the IANA Service Name and Transport Protocol Port Number Registry; security notes are practical guidance, not a substitute for your own risk assessment.
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