Most used ports

Important ports:

FTP: 21
SSH: 22
SFTP: 22 (same as SSH)
HTTP: 80
HTTPS: 443

vs RDS Databases ports:

PostgreSQL: 5432
MySQL: 3306
Oracle RDS: 1521
MSSQL Server: 1433
MariaDB: 3306 (same as MySQL)
Aurora: 5432 (if PostgreSQL compatible) or 3306 (if MySQL compatible)