5318

Port 5318/tcp is registered as pkix-cmc for Certificate Management over CMS (CMC). RFC 10003 says a CMC TCP server should use this port, but the evidence does not establish that a particular host runs CMC or whether the service should be internet-facing; treat its access policy as unknown without deployment context.

CMC carries certificate management messages between clients and certificate or registration authorities. Over TCP, messages use binary encoding without additional wrapping. A client waits for the full response before sending another request on the same connection; reuse of a connection for successive requests is recommended for efficiency.

CMC also supports HTTP, file, and mail transport. RFC 10003 expects HTTP to remain the primary transport in CMC installations, so the TCP assignment alone does not show that this port is commonly deployed. The specification calls for appropriate trust establishment and discusses replay protection; operators should assess those safeguards in their environment.

Service

pkix-cmc is the IANA-assigned TCP service for Certificate Management over CMS (CMC).

Exposure

Unknown. The specification identifies a CMC server port but does not establish an intended public audience.

Security

CMC deployments need suitable trust establishment; replay protections may be needed depending on operational conditions.

Service name

pkix-cmc [Confirmed] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv

Protocol

Certificate Management over CMS (CMC) TCP transport

TCP server port

5318 is the port a CMC TCP server should use [Confirmed] — https://www.rfc-editor.org/rfc/rfc10003.txt

Public internet audience

Unknown [Unknown] — https://www.rfc-editor.org/rfc/rfc10003.txt