2 SNMP agent

Overview

You may want to use SNMP monitoring on devices such as printers, network switches, routers or UPS that usually are SNMP-enabled and on which it would be impractical to attempt setting up complete operating systems and Zabbix agents.

To be able to retrieve data provided by SNMP agents on these devices, Zabbix server must be initially configured with SNMP support.

SNMP checks are performed over the UDP protocol only.

Configuring SNMP monitoring

To start monitoring a device through SNMP, the following steps have to be performed:

Step 1

Create a host for the device with an SNMP interface.

Enter the IP address. Set the host status to NOT MONITORED. You can use one of the provided SNMP templates (Template SNMP Device and others) that will automatically add a set of items. However, the template may not be compatible with the host.

Step 2

Find out the SNMP string (or OID) of the item you want to monitor.

To get a list of SNMP strings, use the snmpwalk command (part of ucd-snmp/net-snmp software which you should have installed as part of the Zabbix installation) or equivalent tool:

shell> snmpwalk -v 2c -c public <host IP> .

As '2c' here stands for SNMP version, you may also substitute it with '1', to indicate SNMP Version 1 on the device.

This should give you a list of SNMP strings and their last value. If it doesn't then it is possible that the SNMP 'community' is different from the standard 'public' in which case you will need to find out what it is.

You can then go through the list until you find the string you want to monitor, e.g. if you wanted to monitor the bytes coming in to your switch on port 3 you would use the IF-MIB::ifInOctets.3 string from this line:

IF-MIB::ifInOctets.3 = Counter32: 3409739121

You may now use the snmpget command to find out the numeric OID for 'IF-MIB::ifInOctets.3':

shell> snmpget -v 2c -c public -On 10.62.1.22 IF-MIB::ifInOctets.3

Note that the last number in the string is the port number you are looking to monitor. See also: Dynamic indexes.

This should give you something like the following:

.1.3.6.1.2.1.2.2.1.10.3 = Counter32: 3472126941

Again, the last number in the OID is the port number.

Step 3

Create an item for monitoring.

So, now go back to Zabbix and click on Items, selecting the SNMP host you created earlier. Depending on whether you used a template or not when creating your host, you will have either a list of SNMP items associated with your host or just a new item box. We will work on the assumption that you are going to create the item yourself using the information you have just gathered using snmpwalk and snmpget, so enter a plain English description in the 'Description' field of the new item box. Make sure the 'Host' field has your switch/router in it and change the 'Type' field to "SNMPv* agent". Enter the community (usually public) and enter the textual or numeric OID that you retrieved earlier into the 'SNMP OID' field, for example: .1.3.6.1.2.1.2.2.1.10.3

Enter the 'SNMP port' as 161 and the 'Key' as something meaningful, e.g. SNMP-InOctets-Bps. Choose a Multiplier if you want one and enter an 'update interval' and 'keep history' if you want it to be different from the default. Set the 'Status' to Monitored, the 'Type of information' to Numeric (float) and the 'Store value' to Delta (speed per second) (important otherwise you will get cumulative values from the SNMP device instead of the latest change).

Now save the item and go back to the hosts area of Zabbix. From here change the SNMP device status to 'Monitored' and check in Latest data for your SNMP data!

Example 1

General example:

Note that OID can be given in either numeric or string form. However, in some cases, string OID must be converted to numeric representation. Utility snmpget may be used for this purpose:

shell> snmpget -On localhost public enterprises.ucdavis.memory.memTotalSwap.0

Monitoring of SNMP parameters is possible if either --with-net-snmp or --with-ucd-snmp flag was specified while configuring Zabbix sources.

Example 2

Monitoring of uptime: