12.2. Common relevant TCP/IP ports

… plus some that are less relevant here.

Port Default function
22 SSH
25 SMTP
80 HTTP
443 HTTPS
465 SMTPS: secure SMTP (e.g. implicit TLS for SMTP via STARTTLS)
587 MSA; e.g. explicit TLS (SSL) for SMTP
1433 Microsoft SQL Server
2575 MLLP/HL7
3306 MySQL
5432 PostgreSQL
5555 Default internal port for Flower
5672 AMQP (e.g. RabbitMQ)
8443 Relatively common alternative for HTTPS (e.g. for testing)
15672 Default internal port for RabbitMQ admin interface