They say MQTT is a PUB/SUB protocol for the Internet of Things, which it was originally designed for, but it's also well suited for monitoring machines and services. Presentation given at BSDCan2019 in Ottawa
+0100 From: MQTTwarn <jpm@localhost> Subject: SSH login on canfb12 X-Mailer: mqttwarn login via sshd by jane on canfb12 from 192.168.33.1 at 2019-03-14 12:19:52