OpenNMS is started but a connection reset error appears in the browser




When you try to connect to the web application you get a “The Connection was reset” in Firefox or “The page isn’t working” in Chrome.


Check if OpenNMS daemons are running with

root@localhost:~# opennms -v status
OpenNMS.Eventd         : running
OpenNMS.Alarmd         : running
OpenNMS.Bsmd           : running
OpenNMS.Ticketer       : running
OpenNMS.Trapd          : running
OpenNMS.Queued         : running
OpenNMS.Actiond        : running
OpenNMS.Notifd         : running
OpenNMS.Scriptd        : running
OpenNMS.Rtcd           : running
OpenNMS.Pollerd        : running
OpenNMS.PollerBackEnd  : running
OpenNMS.EnhancedLinkd  : running
OpenNMS.Collectd       : running
OpenNMS.Discovery      : running
OpenNMS.Vacuumd        : running
OpenNMS.EventTranslator: running
OpenNMS.PassiveStatusd : running
OpenNMS.Statsd         : running
OpenNMS.Provisiond     : running
OpenNMS.Reportd        : running
OpenNMS.Ackd           : running
OpenNMS.JettyServer    : running
OpenNMS.Telemetryd     : running
opennms is running

The important daemon JettyServer is responsible serving the web application. When all services are up and running. Check if the port is open and in state “LISTEN” with:

root@localhost:~# ss -lnpt sport = :8980
State      Recv-Q Send-Q     Local Address:Port     Peer Address:Port
LISTEN     0      50         :::8980                :::*                   users:(("java",pid=61160,fd=902))

Check if you have a firewall running:


systemctl status firewall

See which services are allowed on CentOS with firewalld with

root@localhost:~# firewall-cmd --list-services


The service is running but it is not possible to connect to the service.


Add a rule to your default zone which allows incoming TCP connections to the OpenNMS Web application on port 8980 and restart firewalld.

root@localhost:~# firewall-cmd --permanent --add-port=8980/tcp
root@localhost:~# systemctl restart firewalld

OPENNMS Software Installation