Zabbix agent; why does it listen?

[bvankuik]

Hi guys,

Question I couldn't retrieve from the documentation; why does the Zabbix Agent listen to a port (10050 default). From what I gather, the agents do monitoring and send their data to the server.

In my reasoning, the agents then do not need to listen to a port to receive connections. But I'm missing something and like to learn more on the Zabbix architecture.

[JonB]

The Zabbix agent runs in two modes by default, Active and Passive.

Active

Active refers to a mode that the ZABBIX Agent can run in. When running actively, the agent keeps track of what items to send to the server and at what intervals. The agent can poll the server at set intervals in order to keep track of what items it should be sending.

Passive

Passive refers to a mode that the ZABBIX Agent can run in. When running passively, the agent waits for requests for items from the server and sends them back as requested. It should be noted that typically the agent runs in both modes, and the modes are defined by the Item when it is configured.

You can disable Active mode monitoring in the agent configuration file.

The majority of default templates in Zabbix are all set for Passive mode monitoring i.e the Zabbix server sends to the agent the items it needs to monitor.

To set an item to be monitored actively, i.e the agent contacts the server, the item needs to be set as 'ZABBIX Agent(Active)'

I have set up new templates, for example Template_Windows_Active which is a copy of Template_Windows but all items are 'ZABBIX Agent(Active)'. I use this template to monitor laptops and Windows machines behind firewalls where I can't be bothered opening and forwarding ports to the agents.

Hope this helps explain things.

Jon

[bvankuik]

Great, thanks Jon. I'd read about the two different modes and somehow assumed it couldn't run in both modes at the same time.

This machine is open to the big bad internet, so I think I'm going to shield off the agent port except for the server.