8883
MQTT over TLS — encrypted IoT messaging
MQTT over TLS/SSL
What is port 8883?
Port 8883 is used for MQTT over TLS, the encrypted version of MQTT (port 1883). It is recommended for any IoT deployment using MQTT, especially devices communicating over the public internet. TLS provides both encryption and mutual authentication with client certificates, preventing unauthorized devices from connecting to the broker.
Quick checks
$
nc -zv example.com 8883
$
nmap -p 8883 example.com
$
telnet example.com 8883