WhenIP Academy
Common port numbers and what they are used for
Port numbers help identify services on a host. Memorizing a few common ones makes diagnostics much faster.
What you'll learn
- Which ports are commonly used.
- Why the same service may use more than one port.
- Why a port number alone does not prove the application.
Everyday web and admin ports
80 is commonly HTTP.
443 is commonly HTTPS.
22 is commonly SSH.
3389 is commonly RDP.
Mail and messaging ports
25 is SMTP transport.
587 is submission.
110 and 995 are POP3 and POP3S.
143 and 993 are IMAP and IMAPS.
Infrastructure ports
53 is DNS.
8080 and 8443 are often used for alternate web interfaces or proxies.
Interpretation tips
A port association is a strong hint, not a guarantee. Administrators can bind applications to different ports.
Always confirm with application context, not just the port number.
Mini FAQ
Does port 443 always mean HTTPS?
Usually, but not always.
Can one service use many ports?
Yes. Many applications use one control port and additional data or admin ports.
Last updated: March 29, 2026