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Port Numbers Reference

A reference of commonly used port numbers and what they're for β€” across web, email, file transfer & remote access, databases, network infrastructure, and development.

Web

🌐

80 (TCP)

HTTP - the default port for unencrypted, plain web traffic.

Notes

  • Most websites today automatically redirect HTTP requests to 443 (HTTPS).
πŸ”’

443 (TCP)

HTTPS - the default port for web traffic encrypted with TLS/SSL.

Notes

  • The standard port used by most websites today.
🌐

8080 (TCP)

An alternate HTTP port, commonly used instead of 80 by proxy servers or web apps in development.

Notes

    πŸ”’

    8443 (TCP)

    An alternate HTTPS port, commonly used instead of 443 for admin consoles or certain web applications.

    Notes

      Email

      βœ‰οΈ

      25 (TCP)

      SMTP - the default port for the protocol mail servers use to exchange email with each other.

      Notes

      • Many ISPs block this port for individual users to prevent spam.
      βœ‰οΈ

      587 (TCP)

      SMTP Submission - the recommended port for a mail client to authenticate and send email through a mail server.

      Notes

        πŸ”’

        465 (TCP)

        SMTPS - used for SMTP connections encrypted with TLS.

        Notes

          πŸ“₯

          110 (TCP)

          POP3 - the default port for the protocol that downloads email from a server to your device.

          Notes

            πŸ”’

            995 (TCP)

            POP3S - used for POP3 connections encrypted with TLS.

            Notes

              πŸ“¬

              143 (TCP)

              IMAP - the default port for the protocol that keeps email on the server and syncs it across multiple devices.

              Notes

                πŸ”’

                993 (TCP)

                IMAPS - used for IMAP connections encrypted with TLS.

                Notes

                  File Transfer & Remote Access

                  πŸ“

                  21 (TCP)

                  FTP (control) - the control-channel port used to send commands for the File Transfer Protocol.

                  Notes

                  • Actual data transfer happens over port 20 or a dynamically assigned port.
                  πŸ”‘

                  22 (TCP)

                  SSH - used for encrypted remote access to a server or secure file transfer via SFTP.

                  Notes

                  • The de facto standard for remote server administration today.
                  ⚠️

                  23 (TCP)

                  Telnet - the port for an old, unencrypted remote-access protocol, replaced by SSH today for security reasons.

                  Notes

                    πŸ“

                    69 (UDP)

                    TFTP - a lightweight protocol for simple file transfer without authentication, mostly used for initial setup of network devices.

                    Notes

                      πŸ“

                      445 (TCP)

                      SMB - the port for the protocol used to share files and printers over a network in Windows environments.

                      Notes

                        πŸ–₯️

                        3389 (TCP)

                        RDP - used for Windows Remote Desktop connections.

                        Notes

                          πŸ–₯️

                          5900 (TCP)

                          VNC - the default port for a protocol that shares and controls a screen remotely, independent of operating system.

                          Notes

                            Database

                            πŸ—„οΈ

                            3306 (TCP)

                            The default connection port for MySQL (and MariaDB) database servers.

                            Notes

                              πŸ—„οΈ

                              5432 (TCP)

                              The default connection port for PostgreSQL database servers.

                              Notes

                                πŸ—„οΈ

                                1433 (TCP)

                                The default connection port for Microsoft SQL Server databases.

                                Notes

                                  πŸ—„οΈ

                                  1521 (TCP)

                                  The default listener port for Oracle databases.

                                  Notes

                                    πŸ—„οΈ

                                    27017 (TCP)

                                    The default connection port for MongoDB, a NoSQL document database.

                                    Notes

                                      πŸ—„οΈ

                                      6379 (TCP)

                                      The default connection port for Redis, an in-memory key-value store.

                                      Notes

                                        πŸ—„οΈ

                                        9200 (TCP)

                                        The default HTTP API port for Elasticsearch, a search and analytics engine.

                                        Notes

                                          Network Infrastructure

                                          🌍

                                          53 (UDP/TCP)

                                          DNS - the port for the protocol that resolves domain names (e.g. example.com) into IP addresses.

                                          Notes

                                          • Ordinary lookups use UDP; TCP is used when responses are large or a zone transfer is needed.
                                          🌍

                                          67, 68 (UDP)

                                          DHCP - the port for the protocol that automatically assigns IP addresses to devices on a network (server on 67, client on 68).

                                          Notes

                                            πŸ•

                                            123 (UDP)

                                            NTP - the port for the protocol that synchronizes clocks across devices to a standard time.

                                            Notes

                                              πŸ“‘

                                              161 (UDP)

                                              SNMP - the port for the protocol used to remotely monitor and manage network equipment such as routers and switches.

                                              Notes

                                                πŸ“‡

                                                389 (TCP)

                                                LDAP - the default port for a directory service used to centrally manage users, groups, and similar information within an organization.

                                                Notes

                                                  πŸ”’

                                                  636 (TCP)

                                                  LDAPS - used for LDAP connections encrypted with TLS.

                                                  Notes

                                                    πŸ“Ά

                                                    N/A (ICMP)

                                                    ICMP, used by the ping command, is a separate protocol with no concept of ports, used to check network connectivity.

                                                    Notes

                                                      Development

                                                      πŸ’»

                                                      3000 (TCP)

                                                      A commonly used default port for many front-end/back-end development servers such as Node.js and React.

                                                      Notes

                                                        πŸ’»

                                                        5000 (TCP)

                                                        The default port used by the development server for the Python Flask framework.

                                                        Notes

                                                          πŸ’»

                                                          8000 (TCP)

                                                          The default port used by the development server for the Python Django framework.

                                                          Notes

                                                            πŸ’»

                                                            4321 (TCP)

                                                            The default port used by the development server for the Astro framework.

                                                            Notes

                                                              🐳

                                                              2375, 2376 (TCP)

                                                              Ports used for API communication with the Docker daemon; 2376 is used for TLS-encrypted communication.

                                                              Notes

                                                                What is a port number?

                                                                A single computer can run many network services at once because a port number distinguishes each one. If an IP address points to "which building," a port number is like "which room in that building." Ports 0-1023 are "well-known ports," reserved for standard services like HTTP, HTTPS, and SSH, while 1024-49151 are "registered ports," conventionally used by specific applications.

                                                                A note of caution

                                                                This page is educational content to help with learning networking and development β€” in an actual production service, ports may be configured differently depending on security settings. When opening a port in a firewall or changing server settings, be sure to consider the security risks carefully.

                                                                Frequently Asked Questions

                                                                What's the difference between TCP and UDP?

                                                                TCP is a reliable method that confirms delivery and sends data in order, mainly used for web browsing, email, and file transfer. UDP sends data quickly without a confirmation step, mainly used for services where speed matters, like DNS lookups, live streaming, and online gaming.

                                                                Why should you block certain ports?

                                                                An unnecessarily open port can be an avenue attackers try to exploit. It's safer to block ports for services you're not actually using at the firewall level.

                                                                Can I check which ports are open on my own computer?

                                                                This page is a reference explaining what each port number is used for. To check which ports are actually open on your machine, you'll need a separate network diagnostic tool, such as the netstat command in a terminal or command prompt.