Port 3306 supports MySQL and mysql (UDP reference coverage) across distinct transports. Review each protocol before writing firewall or monitoring policy.
Default MySQL client/server protocol endpoint.
Applications, administrators and replication clients connecting to MySQL or compatible databases.
Client to server
Keep private, require TLS where traffic crosses trust boundaries and use least-privilege database accounts.
mysql (UDP reference coverage) is documented as a network service convention for port 3306 over UDP.
Use this reference entry when identifying or validating systems documented to use 3306/UDP.
Varies
Confirm the listening process and current vendor documentation before permitting traffic; a listed convention does not prove the active service or its security posture.