From Nonecks Docs

apt-get install cacti

1. This will install all the required packages like rrdtool etc
2. For cacti create a new user called cacti using the following command

adduser cacti

1. Create the MySQL database:

shell> mysqladmin --user=root create cacti

1. Import the default cacti database:

shell> mysql cacti < cacti.sql

1. Optional: Create a MySQL username and password for Cacti.

shell> mysql --user=root mysql
mysql> GRANT ALL ON cacti.* TO cactiuser@localhost IDENTIFIED BY 'somepassword';
mysql> flush privileges;

1. Edit include/config.php and specify the MySQL user, password and database for your Cacti configuration.

$database_default = "cacti";
$database_hostname = "localhost";
$database_username = "cactiuser";
$database_password = "cacti";

1. Set the appropriate permissions on cacti's directories for graph/log generation. You should execute these commands from inside cacti's directory to change the permissions.

shell> chown -R cactiuser rra/ log/

1. (Enter a valid username for cactiuser, this user will also be used in the next step for data gathering.)
2. Add a line to your /etc/crontab file similar to:

*/5 * * * * cactiuser php /var/www/html/cacti/poller.php > /dev/null 2>&1

1. Replace cactiuser with the valid user specified in the previous step.
2. Replace /var/www/html/cacti/ with your full Cacti path.
3. Point your web browser to: http://your-server/cacti/
4. Log in the with a username/password of admin. You will be required to change this password immediately. Make sure to fill in all of the path variables carefully and correctly on the following screen.