Which ports are used on a ISPConfig 3 server and shall be open in the firewall?

Here is a list of ports that are used commonly on ISPConfig 3 servers. If you don’t have all services installed or if you e.g. don’t want to connect to MySQL from external servers, then close the unused or unwanted ports.

TCP ports

20 – FTP Data
21 – FTP Command
22 – SSH
25 – Email
53 – DNS
80 – HTTP (Webserver)
110 – POP3 (Email)
143 -Imap (Email)
443 – HTTPS (Secure web server)
993 – IMAPS (Secure Imap)
995 – POP3S (Secure POP3)
3306 – MySQL Database server
8080 – ISPConfig web interface
8081- ISPConfig apps vhost

UDP ports

53 – DNS
3306 – MySQL