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Cacti 0.8 Network Monitoring

Chapter 1. Cacti Overview

Computerization has boosted human intellectual capacity to such a level that a new era of communication has begun. There is hardly any human activity that has not been affected by a computer in one way or another; be it production, agriculture, health, education, military, travel, crime detection, and so on. Naturally, computerization is so deep that we humans can't think of living a single day without it.

In the field of Information Technology, computer communication means networking between computers that can be classified as LAN (Local Area Network), WAN (Wide Area Network), ISDN (Integrated Services Digital Network), and so on. A network is a series of points or nodes interconnected by communication paths. Networks can interconnect with other networks and contain sub-networks. This interconnectivity is done by devices such as routers, switches, hubs, network interface cards (NIC), and so on. In the present infrastructure, devices are very complex, and hard to maintain and monitor, so it is not possible to monitor devices and servers manually at production level.

One of the fundamental jobs of a network administrator is network monitoring. Network monitoring is the process of checking computers, systems, and services that comprise a network. This examination allows a network administrator to maintain a robust network and even improve the network.

You'll never know when a power supply is going to burn out, when a server is going to crash, when network bandwidth drops, when a router just stops working, when your LAN is hacked, and so on. You will never know when these things will happen, but you can be prepared for situations like these. Effective network monitoring will help to cope with such situations and minimize down-time. It will also help to collect periodic information about the network, which will help you to generate log files and performance charts of system capabilities and responses. With such data, you will be able to optimize your network infrastructure and performance.

To do this job effectively, ISO (International Organization for Standardization) designed a model called FCAPS to aid in the understanding of the major functions of a network management system:

Fault management
Configuration management
Accounting management
Performance management
Security management

By implementing network monitoring software, system administrators can gather sufficient amounts of data and reports periodically, which will help them to perform management processes fairly and more easily. There are several commercial and open source network monitoring software that are robust and one-stop guiding tools. Cacti is one such tool, robust and one of the best!

What is Cacti?

Cacti is an open source, network monitoring and graphing tool written in PHP/MySQL. It uses the RRDTool (Round-robin database tool) engine to store data and generate graphics, and collects periodical data through Net-SNMP (an application suite to implement SNMP—Simple Network Management Protocol).

Ian Berry had started developing Cacti back in June 2001, while he was working with a local Internet service provider in the U.S. He found that RRDTool is flexible enough to generate complex graphing and reports about network infrastructures, but it was lacking a friendly interface. So, he started developing the interface with PHP/MySQL and had the first public release (version 0.6) on November 21, 2001. Soon, the application gained its popularity in the open source community.

In 2004, Ian brought a second developer into the team, which has expanded to six developers today. Here they are (in the order of joining the project):

Ian Berry
Larry Adams
Tony Roman
J.P. Pasnak
Jimmy Conner
Reinhard Scheck

Basic knowledge on RRDtool

RRDTool is a high performance data logging and graphing system, designed to handle time series data like network bandwidth, room temperature, CPU load, server load, and to monitor devices such as routers, UPS, etc. It is also known as the round-robin database tool, an industry standard, open source solution. It lets the administrator log and analyze data collected from all kinds of data sources (DS), which are capable of answering SNMP queries. The data analysis part of the RRDTool is based on the ability to generate graphical representations of the data values collected over a definable time period.

RRDTool is developed by Tobi Oeticker, also known for his famous creation MRTG. RRDTool is written in C language and stores its data in .rdd files. The number of records in a single .rrd file never increases, meaning that old records are frequently removed, and it presents useful graphs by processing the data to enforce a certain data density. RRDTool offers several command line switches to access and manipulate .rdd files:

create
update
updatev
graph
dump
restore
fetch
tune
last
info
rrdresize
xport
rrdcgi

Note

Details of the command line switches of the RRDTool can be obtained from http://oss.oetiker.ch/rrdtool/doc/rrdtool.en.html.

There are also a number of language bindings for RRDTool, which allow administrators or programmers to use it directly from Perl, Python, tcl, PHP, and Ruby. So, it can be used to write custom monitoring shell scripts or create whole applications using its language bindings. Cacti is an application written in PHP, using its PHP language binding.

How does the RRDTool work?

RRDTool follows a logical design to acquire and process data collected from data sources (DS). The following is a brief discussion of the different steps in the logical process:

Data acquisition: When monitoring a device or system, it is necessary to receive data on a constant time interval. Manually, it is not possible to maintain such activity as a system administrator. In such situations, the RRDTool comes in handy. It stores the data in a round-robin database, which is received on a constant time interval set by the system administrator, using the poller application set as scheduler in the operating system.
Data consolidation: The system administrator may log the data in a five-minute interval, but he/she might be interested in knowing the accumulated update over the last month. In this case, simply storing the data in a five-minute interval for the whole month will solve the problem. But this will require huge disk space and a considerable amount of time to analyse the data, as in a network environment, administrators are not monitoring only a single device. RRDTool solves this problem with the data consolidation feature. When creating a round-robin database, the administrator can define at which interval data consolidation should occur using consolidation functions (CF) such as MAXIMIUM, AVERAGE, MINIMUM, and others.
Round Robin Archives of consolidated data: Data values of consolidation setup are stored in Round Robin Archives (RRA). In this way, the RRDTool stores data in the most efficient way for a certain time period defined by the system administrator. This process keeps the database file at a constant size for faster processing and analyzing.
Unknown data: RRDTool stores data at a constant interval in a round-robin database. Sometimes, this data might not be available to store in RRD due to device failure or other causes. In this case, the RRDTool stores the RRD file with *UNKNOWN* data value. This *UNKNOWN* value is supported by all RRDTool functions.
Graphing: RRDtool allows system administrator to generate reports in graphical and numerical forms based on data stored in the round-robin database (RDD) by using its built-in graph processing functions. Customization of these graphics is possible based on color, size, and contents.

Key benefits

Install and setup Cacti to monitor your network and assign permissions to this setup in no time at all

Create, edit, test, and host a graph template to customize your output graph

Create new data input methods, SNMP, and Script XML data query

Full of screenshots and step-by-step instructions to monitor your network with Cacti

Description

Cacti is a network monitoring tool that provides graphic solutions to your everyday monitoring issues. It has a wide variety of features and misusing them can mean that you are not monitoring your network as closely as you think. This book takes you through all of the key features of Cacti and shows how to use them for maximum effectiveness. This book will teach you how to use Cacti effectively to monitor your network through its web interface leaving aside all the heavy chunks of code. You will be introduced to all the features of Cacti in an easy-to-understand format. This book introduces Cacti and goes through its complete installation and setup. After a quick look, it will teach you to use Cacti's amazing graph templating and user management features. You will learn to customize graphs and make them better looking and easier to understand. It will teach you to provide the paths to any external script or command using Cacti. Then it will take you through importing and managing new templates and also customizing them. Creating users and assigning permissions to them is the next step in this book. Towards the end, you will learn to take backups and restore the system.

What you will learn

Implement SNMP with Cacti using the Net-SNMP application suite Retrieve raw data from the system using Net-SNMP Create graphs using the RRDtool for easy understanding Add devices to Cacti and use graph templates to monitor your network Use built-in data queries to check the status of your network Import and export your templates and exchange them with the community Create users and assign permissions to them to view or edit graphs Understand how Net-SNMP application suite implements SNMP with Cacti and use Net-SNMP to retrieve raw data from the system, then use the RRDtool to create graphs Understand Cacti s folder structure along with methods of backing up and restoring Use advanced command-line scripts for easy access and managing network

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