Horizon Core has an embedded ActiveMQ instance for convenience that you can enable. It uses the same credentials configured from the web UI for users in the ROLE_MINION role. Edit ActiveMQ configuration file sudo vi etc/opennms-activemq.xml Remove comments for the transport connector listening on 0.0.0.0 and save <transportConnector name="openwire" uri="tcp://0.0.0.0:61616?useJmx=false&maximumConnections=1000&wireformat.maxFrameSize=104857600"/> Restart Horizon Core instance sudo systemctl restart opennms Verify that ActiveMQ port is available on public network interface ss -lnpt sport = :61616 Verify listening 61616/tcp on all interfaces State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:61616 *:* users:(("java",pid=1,fd=706)) If you run a host firewall, allow port 61616/tcp, as in the following example with firewalld: sudo firewall-cmd --permanent --add-port=61616/tcp sudo firewall-cmd --reload