Port 9300 supports Elasticsearch transport and vrace (UDP reference coverage) across distinct transports. Review each protocol before writing firewall or monitoring policy.
Default binary transport for Elasticsearch node-to-node communication.
Cluster formation, replication and coordination between Elasticsearch nodes.
Cluster internal
Keep cluster-internal, require transport TLS and ensure only authorized nodes can join.
vrace (UDP reference coverage) is documented as a network service convention for port 9300 over UDP.
Use this reference entry when identifying or validating systems documented to use 9300/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.