Common network ports
A port is a numbered endpoint that lets a single device run many network services at once. When data arrives, your computer uses the port number to decide which program should receive it — the web browser, the mail client, a database, and so on. Combined with an IP address, a port identifies one specific service on one specific machine: the IP gets the packet to the right device, and the port gets it to the right application.
Port numbers are 16-bit values, so they range from 0 to 65535. They are used by the two main transport protocols: TCP, which sets up a reliable, ordered connection, and UDP, which sends lightweight datagrams without a persistent connection. Many services listen on the same number for both protocols, but a TCP port and a UDP port with the same number are separate.
Port ranges
The full range is split into three groups by the Internet Assigned Numbers Authority (IANA):
| Range | Name | Typical use |
|---|---|---|
0–1023 | Well-known ports | Core services such as HTTP, HTTPS, SSH and DNS; usually require elevated privileges to bind. |
1024–49151 | Registered ports | Applications and vendors register these for specific software (databases, proxies, tools). |
49152–65535 | Dynamic / ephemeral ports | Assigned temporarily by the operating system for the client side of outgoing connections. |
Common ports
The table below lists widely used ports and the services that run on them. Numbers separated by a slash indicate a service that uses more than one port or protocol.
| Port | Protocol | Service | Description |
|---|---|---|---|
20/21 | TCP | FTP | File Transfer Protocol; 21 handles commands and 20 carries data. |
22 | TCP | SSH | Secure Shell for encrypted remote login and file transfer (SCP/SFTP). |
23 | TCP | Telnet | Legacy unencrypted remote login; avoid on modern networks. |
25 | TCP | SMTP | Simple Mail Transfer Protocol for server-to-server mail relay. |
53 | TCP/UDP | DNS | Domain Name System name resolution; see what a DNS server is. |
67/68 | UDP | DHCP | Dynamic Host Configuration Protocol; server on 67, client on 68. |
80 | TCP | HTTP | Unencrypted web traffic. |
110 | TCP | POP3 | Post Office Protocol for downloading email from a mailbox. |
123 | UDP | NTP | Network Time Protocol for clock synchronization. |
143 | TCP | IMAP | Internet Message Access Protocol for reading mail stored on a server. |
161 | UDP | SNMP | Simple Network Management Protocol for monitoring devices. |
194 | TCP | IRC | Internet Relay Chat text messaging. |
443 | TCP | HTTPS | Encrypted web traffic over TLS. |
445 | TCP | SMB | Server Message Block for Windows file and printer sharing. |
465/587 | TCP | SMTP (submission) | Client mail submission; 587 with STARTTLS, 465 with implicit TLS. |
993 | TCP | IMAPS | IMAP over TLS for secure mail access. |
995 | TCP | POP3S | POP3 over TLS for secure mail download. |
3306 | TCP | MySQL | MySQL and MariaDB database connections. |
3389 | TCP | RDP | Remote Desktop Protocol for graphical remote access to Windows. |
5432 | TCP | PostgreSQL | PostgreSQL database connections. |
5900 | TCP | VNC | Virtual Network Computing remote desktop. |
6379 | TCP | Redis | Redis in-memory data store. |
8080 | TCP | HTTP-alt | Alternate HTTP port, often used by proxies and development servers. |
27017 | TCP | MongoDB | MongoDB database connections. |
Ports and your IP
Checking whether a port is open on a host is a different task from finding out what your IP address is. Port scanning asks "can I reach this service?", while this site answers "what public IP am I presenting to the internet?" If you want the latter, you can check your IP address on the home page or fetch it programmatically through the API.
Ports and addresses go hand in hand once you start planning a network. The subnet calculator helps you work out address ranges and host counts, and the guide to private IP ranges explains which addresses stay inside your local network — the same networks where you will typically expose internal services on the ports listed above.
A note on security
A port can be open (a service is listening and reachable), closed (nothing is listening), or filtered (a firewall is silently dropping the traffic). Firewalls and network address translation mean that most services running behind a home or office router are not reachable from the public internet unless a port is deliberately forwarded.
That default is a good thing. Sensitive services such as remote desktop (3389) and databases (3306, 5432, 6379, 27017) should almost never be exposed directly to the public internet — they are frequent targets for automated attacks. Keep them behind a firewall or VPN, restrict access to known addresses, and always require strong authentication and encryption.