Port 135 supports Microsoft RPC Endpoint Mapper and epmap (UDP reference coverage) across distinct transports. Review each protocol before writing firewall or monitoring policy.
Maps Microsoft RPC clients to dynamically assigned service ports.
Windows administration, WMI, Active Directory replication and distributed services.
Client to server
Exposure frequently implies a wider dynamic RPC range. Limit it to trusted management and domain networks.
epmap (UDP reference coverage) is documented as a network service convention for port 135 over UDP.
Use this reference entry when identifying or validating systems documented to use 135/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.