Attribute / Project | [OpenNMS](https://www.opennms.org/) | [Nagios](http://www.nagios.org/) | [Zenoss](http://www.zenoss.org/) | Hyperic | [Zabbix](http://www.zabbix.com/) |
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Peer Support |
Forum |  |  |  |  |  |
Mailing list |  |  |  |  |  |
Commercial Support |
Support contract |  |  |  |  |  |
Training |  |  |  |  |  |
Consulting |  |  |  |  |  |
Learning resources |
Blog |  |  |  |  |  |
Book(s) |  |  |  |  |  |
**Update 1**: Zenoss has a forum / mailing list system. Both interoperate together so a post to one goes automatically into the other