How to Setting Up a SNMP Server and Cacti in Ubuntu

What is net-snmp ?

Simple Network Management Protocol (SNMP) is a widely used protocol for monitoring the health and welfare of network equipment (eg. routers), computer equipment and even devices like UPSs. Net-SNMP is a suite of applications used to implement SNMP v1, SNMP v2c and SNMP v3 using both IPv4 and IPv6.

Cacti on the other hand is a frontend to the RRDTool with SNMP support. It collects and keep data in a MySQL database and display them through a PHP web frontend.

SNMPD

SNMPD is the service running SNMP on a managed entity. SNMP comes in 3 versions. Version 1, the one we are going to use here is not secured, therefore we are going to make sure that only localhost is going to be able to access it.

People opening the service to the outside should make sure that trusted hosts can access the service either though the use of iptables or through the use of /etc/hosts.allow.

Installing The SNMP Server

The only package which is required on the server site is snmpd, the SNMP daemon.

To install it type:

$ sudo apt-get install snmpd

snmpd is now installed but we still have to tweak it a little bit to make it work as we want.

Configuring SNMPD

The first thing we want to make sure is that snmpd is only going to wait for connections on localhost. To do this, edit file /etc/default/snmpd and make sure those values are set:

SNMPDRUN=yes

SNMPDOPTS='-Lsd -Lf /dev/null -u snmp -I -smux -p /var/run/snmpd.pid 127.0.0.1'

If you want your server to listen on all interfaces, remove the 127.0.0.1 bit.

This setting will make sure that the service will be started and that the service is going to bind to localhost.

Finally, we are going to configure snmpd in such a way that it will only return datas to trusted host for a specific community.

Edit /etc/snmp/snmpd.conf and make sure that com2sec it only set to:

com2sec readonly localhost mycommunity

If you want a remote machine to be able to gather information for the community mycommunity, make sure you replace localhost by mynetwork, where mynetwork can be of the form: 1.1.1.1 or 1.1.0.0/16.

Checking SNMP Configuration:

We are going to use the snmpwalk utility to verify that the server is working as wanted.

Here we want snmp to reply only to localhost for the community mycommunity.

From localhost

# Restart snmpd to load de new config #####

$ sudo /etc/init.d/snmpd restart


# Test the SNMP Server #####

$ sudo apt-get install snmp

$ snmpwalk -Os -c mycommunity -v 1 localhost system

Should return a lot of output and:

snmpwalk -Os -c public -v 1 localhost system

Timeout: No Response from localhost

If the second command returns result, it might be because you did not comment the line starting with com2sec.

Installing Cacti

Cacti displays system statistics through a PHP/MySQL web interface.

To gather informations, it runs a script which is going to poll the servers you registered in cacti: /usr/share/cacti/site/poller.php.

So, let's get started an install cacti.

Installing Cacti Packages And Dependencies

# apt-get install mysql-server apache2 libapache2-mod-php5 php5-mysql php5-cli php5-snmp
# apt-get install cacti

Note: because I am using php5, I had to install all the required php5-xx packages before I installed cacti. If you don't install those first, cacti will fall back to apache2 with php4.

While installing cacti, you are going to be asked a few question, answer as follow:

configuring libphp-adodb
-> press ok
configuring cacti
configure database for cacti with dbconfig-common
-> press yes
password of your database's administrative user
-> mysql root password (empty by default, fill accordingly)
mysql application password for cacti
-> give the password you would like cacti to connect to mysql with
webserver type
-> Apache2

Now, cacti is installed, let's configure it:

Configuring Cacti

Now, cacti is installed as well as its database. We still need through a few configuration screens before we can start adding servers to monitor.

Let's go to http://your-manager-server.ip/cacti/

• Click next to the first screen
• Select new install and check that the found informations are correct
• Check that everything is [FOUND]
• Click Finish

Finally, you should be landing on the login page. Log in with username: admin and password: admin. The next screen will force you to change your password.

On the first login, the default account is admin with password admin

Voila, our manager is up and running, the last step is to create new Devices (adding new hosts to our manager).

Enjoy ubuntu.... ;)

Tq http://www.debuntu.org