Enable SNMP Monitoring on Ubuntu 12.04

SNMP is the Simple Network Management Protocol. It can allow you to keep an eye on various machines with tools like Nagios and Cacti. Watch for spikes of network activity, see how much memory is used in a day's time, or do some customization and compare spams to hams.A workstation can be watched, too. And that's what I hope to show here.

Installing the software
You'll need the package called snmpd (the daemon) and snmp (the tools).
Install SNMPD  
$ sudo apt-get install snmpd
Create a backup file of snmpd.conf original file that we will edit later
$ sudo mv /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.ori
Create the new snmpd.conf file
$ sudo vim /etc/snmp/snmpd.conf
Add the file with these lines
rocommunity public
syslocation "Your Location"
syscontact admin@yourdomain.com
Then edit the /etc/default/snmpd file
$ sudo vim /etc/default/snmpd
Disable this line below by adding # in front of the line
#SNMPDOPTS='-Lsd -Lf /dev/null -u snmp -g snmp -I -smux -p /var/run/snmpd.pid'
And add a new line
SNMPDOPTS='-Lsd -Lf /dev/null -u snmp -I -smux -p /var/run/snmpd.pid -c /etc/snmp/snmpd.conf'
Restart the SNMPD service
$ sudo /etc/init.d/snmpd restart
* Restarting network management services
Then you're done!

http://andrewpakpahan.blogspot.in/2012/09/how-to-enable-snmp-monitoring-on-ubuntu.html