Port 5683 — CoAP
Quick reference for TCP/UDP port 5683, used by CoAP. Includes what the service does, security guidance and related ports.
What is port 5683?
Constrained Application Protocol — IoT.
What port does CoAP use?
CoAP listens on port 5683 by default.
Is port 5683 open? How to check
Run one of these from your computer, replacing HOST with the IP address or domain you want to test.
nc -zvu HOST 5683
Test-NetConnection HOST -Port 5683
nmap -sU -p 5683 HOST
A refused or timed-out connection means the port is closed or filtered by a firewall.
Security guidance
Medium risk — open with care
Port 5683 (CoAP) can safely face the internet if you keep the software up to date, restrict admin endpoints, and use TLS where possible. Audit who can reach it and watch your logs.
Related ports
Frequently asked
What is port 5683 used for?+
Port 5683 is the standard TCP/UDP port for CoAP. Constrained Application Protocol — IoT.
What port does CoAP use?+
CoAP listens on port 5683 by default.
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