Now that we are familiar with monitoring using Zabbix agents and the agentless method, let's explore an additional method that does not require Zabbix agent installation, even though it needs an agent of some kind anyway. Simple Network Management Protocol (SNMP) is a well-established and popular network-monitoring solution. We'll learn to configure and use SNMP with Zabbix, including SNMP polling and trap receiving.
Being more than two-decades old, SNMP has had the time to become widespread across a whole range of networked devices. Although the name implies management functionality, it's mostly used for monitoring. As the first versions had security drawbacks, the ability to modify configuration over SNMP did not become as popular as its read-only counterpart.
SNMP as the primary monitoring solution is especially popular in embedded devices, where running a complete operating system and installing separate monitoring agents would be overkill. Two of the most popular device categories implementing SNMP out of the box are printers and various network devices, such as switches, routers, and firewalls. SNMP allows the easy monitoring of these otherwise quite closed devices. Other devices with SNMP agents provided include UPSes, Network-Attached Storage (NAS) devices, and computer rack temperature/humidity sensors. Of course, SNMP is in no way restricted to devices with limited processing power—it's perfectly fine to run a generic SNMP agent instead of a specialized monitoring agent on standard servers. Reasons to use SNMP agents instead of Zabbix agents might include already installed and set up SNMP agents, no access to monitored hosts to install Zabbix agents, or a desire to keep systems relatively free from dependencies on monitoring software.
Given the prevalence of SNMP, it's no wonder Zabbix supports it out-of-the-box. SNMP support in Zabbix builds upon another quality open source product—Net-SNMP (http://net-snmp.sourceforge.net/).
In this chapter, we will do the following:
- Look at basic Net-SNMP tools
- Learn how to add Management Information Base (MIB) files so that Zabbix recognizes them
- Poll SNMP items in Zabbix
- Receive SNMP traps