5683

IANA registers UDP port 5683 as coap for the Constrained Application Protocol (CoAP), specified by RFC 7252. Whether any particular host runs CoAP on this port, and whether it should be reachable from the public internet, are Unknown from the supplied evidence.

CoAP is a request/response protocol for constrained devices and networks, including machine-to-machine applications such as smart energy and building automation. It runs over UDP and supports unicast and multicast requests. Confirmable messages provide optional reliability through acknowledgements and retransmission; other messages can be sent without reliability.

CoAP can carry resource requests and responses, support discovery, and interact with HTTP through proxies. The RFC also describes security using DTLS and discusses risks including amplification and IP address spoofing. The evidence does not establish the security of any particular deployment, its traffic prevalence, or its exposure policy.

Registered service

coap is IANA’s service name for UDP port 5683. [Confirmed]

Public access

Unknown; the registration and protocol description do not establish an appropriate audience or policy for a specific deployment. [Unknown]

Security

CoAP has a DTLS security binding, while the RFC discusses amplification and spoofing risks. [Confirmed]

Service name

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

Protocol reference

RFC 7252, The Constrained Application Protocol

Protocol behavior

UDP binding supports unicast and multicast requests with optional reliability

Deployment exposure

Unknown from the supplied evidence [Unknown] — https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv