SNMP/Examples/Example 3:Extending SNMP

From ImageStream Router Documentation

SNMP can be extended by inserting the output of a command into the tree. This allows you to write scripts to fetch any information you like and monitor that data similar to interface statistics, RAM usage, and CPU load.

This example feeds voltage, CPU fan speed, and CPU temperature information into the SNMP tree at OID .1.3.6.1.4.1.2021.54. First save the following to /root/bin/snmpsensors.

#!/bin/bash
Start sensors >/dev/null 2>&1
sensors -c /usr/share/etc/sensors.conf >/dev/null 2>&1
fields="$(sensors -c /usr/share/etc/sensors.conf|grep -vi isa |cut -f 2 -d : | awk '{print $1}')"
for f in $fields ; do
  echo $f 1 '*' | dc
done
Stop sensors>/dev/null 2>&1

Then run chmod 755 /root/bin/snmpsensors Last, add exec .1.3.6.1.4.1.2021.54 sensors /root/bin/snmpsensors to your SNMP configuration and restart SNMP.

The output of snmpwalk looks like this:

rjune@rjune-desktop:~$ snmpwalk -v 2c -c public gw01 .1.3.6.1.4.1.2021.54
UCD-SNMP-MIB::ucdavis.54.1.1 = INTEGER: 1
UCD-SNMP-MIB::ucdavis.54.2.1 = STRING: "sensors"
UCD-SNMP-MIB::ucdavis.54.3.1 = STRING: "/root/bin/snmpsensors"
UCD-SNMP-MIB::ucdavis.54.100.1 = INTEGER: 0
UCD-SNMP-MIB::ucdavis.54.101.1 = STRING: "1.76"
UCD-SNMP-MIB::ucdavis.54.101.2 = STRING: "3.5"
UCD-SNMP-MIB::ucdavis.54.101.3 = STRING: "4.8"
UCD-SNMP-MIB::ucdavis.54.101.4 = STRING: "12.16"
UCD-SNMP-MIB::ucdavis.54.101.5 = STRING: "5.26"
UCD-SNMP-MIB::ucdavis.54.101.6 = STRING: "3.34"
UCD-SNMP-MIB::ucdavis.54.101.7 = STRING: "8035"
UCD-SNMP-MIB::ucdavis.54.101.8 = STRING: "35"
UCD-SNMP-MIB::ucdavis.54.101.9 = STRING: "1.75"
UCD-SNMP-MIB::ucdavis.54.102.1 = INTEGER: 0
UCD-SNMP-MIB::ucdavis.54.103.1 = ""