Chapter 14. Frequently Asked Questions

1. Using Cacti

How do I create traffic graphs?

Before you can create traffic graphs, Cacti must have working SNMP support. One way to do this is to compile

PHP with SNMP support built in, many times you can install the 'php snmp' package to do this. The second

option is to have Cacti call the snmpget and snmpwalk binaries from your ucd snmp or

net snmp

installation.

You can use the about page to determine whether to are using "built in" or "external" SNMP support.

Now that you have working SNMP support, follow these steps.

1. Click Devices on Cacti's menu.

2. Click Add to add a new device.

3. Type a description, hostname, management IP, and SNMP community. Make sure to select "Generic SNMP 

enabled Host" under Host Template and click Create.

4. Click Create Graphs for this Host at the top of the page.

5. You should see one or more interfaces listed under the Data Query [SNMP   Interface Statistics] box. Place a

check next to each interface that you want to graph. Below the box, select type of graph that you want to

create (bits, bytes, summation, etc).

6. Click Create, and Create again on the following screen to create your graphs.

2. General

I get a "Undefined variable: _SERVER" error message from Cacti.

Cacti 0.8 and above requires that you have at least PHP 4.1 or greater installed.

I get a "Call to undefined function: mysql_connect()" error message from Cacti.

Your installation of PHP does not have MySQL installed or enabled. On binary based distributions, make sure

you have the 'php mysql' package installed. Also make sure that 'extension=mysql.so' is uncommented in your

php.ini file.

I have forgotten my 'admin' password to Cacti, how do I reset it?

To reset the admin account password back to the default of 'admin', connect to your Cacti database at the com 

mand line.

shell

>

mysql  u root  p cacti

Now execute the following SQL:

mysql

>

update user_auth set password='21232f297a57a5a743894a0e4a801fc3' where username='admin';

3. Monitoring

I am polling thousands of items and poller.php takes more than 5 minutes to run.

Give cactid, the future replacement for poller.php a try. Unlike poller.php, cactid is written in c and makes use of

pthreads. On a typical installation, it is not uncommon for cactid to poll about 500 items in less then 10 seconds.

I changed x, and now some of my graphs are not updating.

The best thing to do here is to force Cacti to rebuild its poller cache. To do this click Utilities on the Cacti menu,

and select Clear Poller Cache.

I am using

Redhat 8.0

and SNMP is not working.

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