Most of the ports used by Plesk and its related services are TCP, but some important ones use UDP or both TCP and UDP protocols.
Here is a summary highlighting which ports are TCP, UDP, or both:
| Port | Protocol | Service |
|---|---|---|
| 20 | TCP | FTP data transfer (active mode) |
| 21 | TCP | FTP control |
| 22 | TCP | SSH (Secure Shell) |
| 25 | TCP | SMTP (Mail sending) |
| 53 | TCP and UDP | DNS (Domain Name System) |
| 80 | TCP | HTTP (Web server) |
| 110 | TCP | POP3 (Mail retrieval) |
| 123 | UDP | NTP (Network Time Protocol) |
| 143 | TCP | IMAP (Mail retrieval) |
| 443 | TCP (Also UDP varies) | HTTPS (Secure web server & licensing) |
| 465 | TCP | SMTPS (SMTP over SSL) |
| 587 | TCP | SMTP Submission |
| 993 | TCP | IMAPS (IMAP over SSL) |
| 995 | TCP | POP3S (POP3 over SSL) |
| 3306 | TCP | MySQL database |
| 5432 | TCP | PostgreSQL database |
| 8443 | TCP | Plesk administration interface (HTTPS) |
| 8880 | TCP | Plesk administration interface (HTTP) |
The only important UDP ports to note are:
- Port 53 (DNS) uses both UDP and TCP (mainly UDP for queries, TCP for zone transfers).
- Port 123 (NTP) is UDP only.
All other Plesk-related service ports primarily use TCP.
Opening required TCP ports and these UDP ports (53 and 123) in firewalls is necessary for proper Plesk functionality and networking.
note: 3306 may stay closed if only used locally by your domain
SSH should be set to only allow specific IP addresses (like yours) for maximum security.
For port 443, which is the standard port for HTTPS, the primary and universally recognized protocol is TCP. HTTPS traffic uses TCP for establishing a secure, reliable connection with SSL/TLS encryption.
However, there is also a newer protocol, HTTP/3, which uses UDP on port 443 with the QUIC transport protocol for faster performance. So, if you want to support all modern variants of HTTPS including HTTP/3, it is recommended to allow both TCP and UDP on port 443.
Summary:
- Traditional HTTPS: TCP port 443 only
- Modern HTTP/3 with QUIC: UDP port 443 also needed
- For full compatibility on web servers and firewalls, allow both TCP and UDP on 443
If uncertain, enabling TCP 443 is essential and UDP 443 is optional but becoming more common as HTTP/3 adoption grows.