Wednesday, December 29, 2010

NDOUtils installation on CentOS for Nagios

NDOUtils installation on CentOS

NDOUtils Requirements

GCC-C++
MySQL
MySQL-Devel
MySQL-Server

Installing MySQL

# yum -y install mysql mysql-devel mysql-server gcc-c++

# /etc/init.d/mysqld start

# chkconfig --add mysqld

-> make sure it's running

# ps -ef | grep mysql

-> Creating MySQL DB

mysql -u root

(no password

#Now, inside MySQL shell

mysql>create database nagios;

Query OK, 1 row affected (0.00 sec)

mysql>show databases;

+----------+

| Database |

+----------+

| database |

| mysql |

| nagios |

| test |

+----------+

4 rows in set (0.01 sec)

mysql>

Create a username/password that has at least the following privileges for the database: SELECT, INSERT, UPDATE, DELETE"

mysql> GRANT ALL ON nagios.* TO nagios@localhost IDENTIFIED BY "example";

Query OK, 0 rows affected (0.00 sec)

mysql> FLUSH PRIVILEGES;

Query OK, 0 rows affected (0.00 sec)

mysql> quit

-> NDOUtils Install

Download and untar

# cd /usr/local/nagios/var/

# wget http://internap.dl.sourceforge.net/sourceforge/nagios/ndoutils-1.4b9.tar.gz

# tar zxfv ndoutils-1.4b9.tar.gz

-> Compiling

# cd ndoutils-1.4b9

# ./configure

# make

Look through config.log for problems.

# less config.log

(If problems, run "make clean" to blow away bad binaries)

-> Copying Binaries

ndomod

There are two different versions of the NDOMOD module that get compiled, so make sure you use the module that matches the version of Nagios you are running, and adjust the directions given below to fit the name of the module version you're using.

ndomod-2x.o = NDOMOD module for Nagios 2.x ndomod-3x.o = NDOMOD module for Nagios 3.x (unstable)

In our CentOS example, we use the stable 2.x version

# /usr/local/nagios/var/ndoutils-1.4b9/src/ndomod-2x.o

Copy the compiled NDOMOD module to your Nagios installation:

# cp /usr/local/nagios/var/ndoutils-1.4b9/src/ndomod-3x.o /usr/local/nagios/bin/ndomod.o

ndo2db

There are two different versions of the NDO2DB daemon that get compiled, so make sure you use the daemon that matches the version of Nagios you are running, and adjust the directions given below to fit the name of the daemon you're using.

ndo2db-2x.o = NDO2DB daemon for Nagios 2.x ndo2db-3x.o = NDO2DB daemon for Nagios 3.x (unstable)

Copy the compiled NDO2DB daemon to your Nagios installation:

# cp /usr/local/nagios/var/ndoutils-1.4b9/src/ndo2db-2x /usr/local/nagios/bin/ndo2db

-> Creating NDO database

It's time now to create the NDO MySql database Run the DB installation script in the /tmp/ndoutils-1.4b9/db/ subdirectory of the NDO distribution to create the necessary tables in the database.

(-u = user; -p = password; -h = name of computer; -d = MySQL DB)

# cd /usr/local/nagios/var/ndoutils-1.4b9/db

# ./installdb -u nagios -p password -h localhost -d nagios

DBD::mysql::db do failed: Table 'nagios.nagios_dbversion' doesn't exist at ./installdb line 51.

** Creating tables for version 1.4b9

Using mysql.sql for installation...

** Updating table nagios_dbversion

Done!

We'll need to later make sure that the database name, prefix, and username/password we created and setup match the variable specified in our NDO2DB config file (which will ultimately live in /etc/nagios/)

CFG File Changes for CentOS-MySQL Environment

ndo2db.cfg

# cp //usr/local/nagios/var/ndoutils-1.4b9/config/ndo2db.cfg /usr/local/nagios/etc/

->in ndo2db.cfg

# SOCKET TYPE

# This option determines what type of socket the daemon will create

# an accept connections from.

# Value:

# unix = Unix domain socket (default)

# tcp = TCP socket

socket_type=unix

#socket_type=tcp

. . .

# SOCKET NAME

# This option determines the name and path of the UNIX domain

# socket that the daemon will create and accept connections from.

# This option is only valid if the socket type specified above

# is "unix".

socket_name=/usr/local/nagios/var/ndo.sock

#socket_name=/var/run/nagios/ndo.sock

. . .

# DATABASE USERNAME/PASSWORD

# This is the username/password that will be used to authenticate to the DB.

# The user needs at least SELECT, INSERT, UPDATE, and DELETE privileges on

# the database.

#db_user=ndouser

#db_pass=ndopassword

db_user=nagios

db_pass=password

ndomod.cfg

Copy the sample NDOMOD config file to your Nagios installation

Note: this config is not ready yet; we will need to modify it later to our environment.

# cp //usr/local/nagios/var/ndoutils-1.4b9/config/ndomod.cfg /usr/local/nagios/etc/

Add a line similiar to the following to the *main* Nagios config file (usually /usr/local/nagios/etc/nagios.cfg):

nagios.cfg file (all one one line, this cfg_file!=confg_file variable)

broker_module=/usr/local/nagios/bin/ndomod.o config_file=/usr/local/nagios/etc/ndomod.cfg

The config directive above will cause Nagios to load the NDOMOD event broker the next time it starts. Of course, this requres that you compiled Nagios with support for the event broker in the first place, which is not a problem if we installed via package (via RPMforge repository).

Make sure you have a line similar to the following in the *main* Nagios config file (usually /usr/local/nagios/etc/nagios.cfg):

event_broker_options=-1

That directive will cause the Nagios daemon to send data to the NDOMOD module. Without that option, NDOMOD won't get any information. Finaly make sure that output parameter in ndomod.cfg is set up to

output=//usr/local/nagios/var/ndo.sock

It's very important that output parameter has exactly the same value as socket_name parameter in ndo2db.cfg file. If not, you will get this message when starting nagios daemon.

[1192222122] ndomod: Error writing to data sink! Some output may get lost...

Start NDO2DB daemon

# /usr/local/nagios/bin/ndo2db -c /usr/local/Nagios/etc/nagios/ndo2db.cfg

[root@localhost nagios]# ps -ef | grep ndo2db

nagios 26516 1 0 19:36 ? 00:00:00 ndo2db -c /etc/nagios/ndo2db.cfg

root 26536 26460 0 19:40 pts/0 00:00:00 grep ndo

[root@localhost nagios]#

restart Nagios

# /etc/init.d/nagios restart

Proof it's working:

# tail /var/log/nagios/nagios.log

[1192222138] ndomod: Successfully reconnected to data sink! 0 items lost, 68 queued items to flush.

[1192222138] ndomod: Successfully flushed 68 queued items to data sink.

Nagios and nrpe setup CentOs

Nagios and nrpe setup CentOs 5.3 :

Nagios/nrpe how to :

For this session, I am demonstrating a basic Nagios set up of nrpe.

There are two hosts involved.
1. The nagios host. (the master node; where the nagios web ui is)
2. The remote host (the node you want to monitor remotely from the master node)

Software Versions involved:
both hosts: CentOS release 5.3 (Final) (64 bit)

master node:
Nagios® Core™ Version 3.2.0
nagios.x86_64 3.2.0-1.el5.rf (yum install)

remote host:
nagios-nrpe.x86_64 2.12-1.el5.rf (yum install)

(I assume you have a basic nagios set up already - this is just to enable nrpe)

nagios host: (master)

$ sudo yum install nagios-plugins-nrpe nrpe

$ sudo chown nagios.nagios /etc/nagios/nrpe.cfg

$ sudo vi /etc/nagios/objects/commands.cfg

# add

define command{

command_name check_nrpe

command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$

}

$ sudo vi /etc/nagios/objects/myremote_host.cfg

# add

define service{

use remote-service

host_name example.com

service_description Check Remote Users

check_command check_nrpe!check_users

}

# nrpe (remote checks) syntax is check_nrpe(as defined above) ! 'command to

run' (as defined on remote host, see below)

remote host: (node to be remotely monitored)
(NOTE: nagios itself should not be installed on this host)

$ sudo yum install nagios-nrpe

$ cd /etc/nagios

$ sudo chown nagios.nagios *.cfg

$ sudo vim /etc/xinetd.d/nrpe

# add

service nrpe

{

flags = REUSE

type = UNLISTED

port = 5666

socket_type = stream

wait = no

user = nagios

group = nagios

server = /usr/sbin/nrpe

server_args = -c /etc/nagios/nrpe.cfg --inetd

log_on_failure += USERID

disable = no # was yes

only_from = NAGIOS_MASTER_IP (master nagios host you want to

connect from) # was localhost

}

$ sudo vim cat /etc/hosts.allow

# add same ip from xinetd above

NAGIOS_MASTER_IP

$ sudo vim /etc/nagios/nrpe.cfg

#allowed_hosts=127.0.0.1 #

# add same ip from xinetd above

allowed_hosts=NAGIOS_MASTER_IP

$ sudo vim /etc/services

# append this line to the file

# Local services

nrpe 5666/tcp # nrpe (nagios)

$ sudo /sbin/service nrpe start

Starting Nagios NRPE daemon (nrpe): [ OK ]

$ sudo /etc/init.d/xinetd reload

$ sudo /sbin/chkconfig --list |grep nrpe

nrpe 0:off 1:off 2:off 3:off 4:off 5:off 6:off

nrpe: off

$ sudo /sbin/chkconfig --levels 35 nrpe on

$ sudo /sbin/chkconfig --list |grep nrpe

nrpe 0:off 1:off 2:off 3:on 4:off 5:on 6:off

nrpe: off

$ netstat -an | grep 5666

tcp 0 0 0.0.0.0:5666 0.0.0.0:* LISTEN

ok, good, it's running

now from nagios (master) server:
(can we see it's running too?)
telnet REMOTE_HOST_WE_JUST_CONFIGURED_IP 5666

$ /usr/lib64/nagios/plugins/check_nrpe -H REMOTE_HOST_WE_JUST_CONFIGURED_IP -p5666 -c check_disk1

to add new commands to be run via nrpe, we must add those to the remote host, nrpe.cfg file:

added new test on remote host:
$ sudo vim /etc/nagios/nrpe.cfg
command[check_mapper]=/usr/lib64/nagios/plugins/check_disk -w 20% -c 10% -p /dev/sda5

test from master node:
$ /usr/lib64/nagios/plugins/check_nrpe -H REMOTE_HOST_WE_JUST_CONFIGURED_IP -p5666 -c check_mapper
DISK OK - free space: / 41180 MB (50% inode=99%);| /=40614MB;68993;77617;0;86242

helpful master node commands:
server config test:
$ sudo /usr/bin/nagios -v /etc/nagios/nagios.cfg
#start/stop/restart:
$ sudo /sbin/service nagios restart
#command line check commands against remote host:
$ /usr/lib64/nagios/plugins/check_nrpe -H REMOTE_SERVER_IP -p5666 -c check_disk1

Wednesday, December 15, 2010

Installing Nagios on CentOS

1. First we make sure these prerequisites are installed and up to date
Run these commands from a command line:
-> yum install httpd
-> yum install gcc
-> yum install glibc glibc-common
-> yum install gd gd-devel

2. Elevate to root
From command line:
-> su -

3. Create a new nagios user account and give it a password
From command line:
-> /usr/sbin/useradd -m nagios
-> passwd nagios
Type the new password twice.

4.Create a new nagcmd group for external commands
From Command line:
-> /usr/sbin/groupadd nagcmd
-> /usr/sbin/usermod -a -G nagcmd nagios
-> /usr/sbin/usermod -a -G nagcmd apache

5. Create a directory to install Nagios
From command line:
-> mkdir downloads
-> cd dowloads/

6. Download source code from http://www.nagios.org/download/
These commands will download version 3.2.0 of the Core Nagios files and version 1.4.13 of the Nagios plugins.
From command line:
-> wget http://downloads.sourceforge.net/project/nagios/nagios-3.x/nagios-3.2.0/nagios-3.2.0.tar.gz?use_mirror=softlayer
-> wget http://downloads.sourceforge.net/project/nagiosplug/nagiosplug/1.4.13/nagios-plugins-1.4.13.tar.gz?use_mirror=softlayer

7. Extract and compile nagios-3.0.6.tar.gz
From Command line:
-> tar -xzvf nagios-3.0.6.tar.gz
-> cd nagios-3.0.6
-> ./configure --with-command-group=nagcmd
-> make all
-> make install
-> make install-init
-> make install-config
-> make install-commandmode

8. Edit the /usr/local/nagios/etc/objects/contacts.cfg config file. Change the email address associated with the nagiosadmin contact to the address you'd like to use for receiving alerts.
From command line:
-> vi /usr/local/nagios/etc/objects/contacts.cfg

9. Install the Nagios web config file in the Apache conf.d directory
From command line:
-> make install-webconf

10. Create a nagiosadmin account for logging into the Nagios web interface
From command line:
-> htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin

11. Restart Apache
From command line:
-> service httpd restart

12. Compile and Install the Nagios Plugins
From command line:
-> cd downloads/
-> tar xzf nagios-plugins-1.4.11.tar.gz
-> cd nagios-plugins-1.4.11
-> ./configure --with-nagios-user=nagios --with-nagios-group=nagios
-> make
-> make install

13. Add Nagios to the list of system services
From command line:
-> chkconfig --add nagios
-> chkconfig nagios on

14. Check for config errors
From command line:
-> /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg

15. Start Nagios
From command line:
-> service nagios start

16. Login to the Web Interface using username (nagiosadmin) and password you specified earlier
From your internet browser navigate to the following URL:
http:///nagios

Introduction to Linux for beginners

History

UNIX

In order to understand the popularity of Linux, we need to travel back in time, about 30 years ago, imagine computers as big as houses, even stadiums. While the sizes of those computers posed substantial problems, there was one thing that made this even worse: every computer had a different operating system. Software was always customized to serve a specific purpose, and software for one given system didn’t run on another system. Being able to work with one system didn’t automatically mean that you could work with another. It was difficult, both for the users and the system administrators. Computers were extremely expensive then, and sacrifices had to be made even after the original purchases just get the users to understand how they worked. The total cost of IT was enormous. Technologically the world was not quite that advanced, so they had to live with the size for another decade. In 1969, a team of developers in the Bell Labs laboratories started working on a solution for the software problem, to address these compatibility issues.

Bell Labs

UNIX was originally developed for internal use at AT&T Bell Labs by researchers Ken Thompson and Dennis Ritchie. AT&T licensed the source code, widely allowing many companies to modify and produce UNIX-like operating systems. Because AT&T held the UNIX name, other companies had to create their own names to brand the modifications ad additions they had made: AIX from IBM, HP/UX from Hewlett-Packard, SunOS (later Solaris) from Sun, and Mac from Apple.

They developed a new operating system, which was Simple and elegant.

Features

Written in the C programming language instead of in assembly code.
Able to recycle code.
the Bell Labs developers named their project “UNIX”

The code recycling features were very important. Until then, all commercially available computer system were written in code specifically developed for one system. UNIX on the other hand needed only a small piece of that special code, which is now commonly named the kernel. This kernel is the only piece of code that needs to be adapted for every specific system and forms the base of the UNIX system. The operating system and all other functions were built around this kernel and written in a higher programming language ‘C’.

This language was especially developed for creating the UNIX system. Using this new technique, it was much easier to develop an operating system that could run on many different types of hardware.

The software vendors were quick to adapt, since they could sell ten times more software almost effortlessly. Weird new software came in existence: imagine for instances computers from different vendors communicating in the same network, or users working on different systems without the need for extra education to use another computer. UNIX did a great deal to help users become compatible with different systems. Throughout the next couple of decades the development of UNIX continued. More things became possible to do and more hardware and software vendors added support for UNIX to their products. UNIX was initially found only in very large environments with mainframes and minicomputers (note that a PC a “micro” computer). You had to work at a university, for the government or for large financial corporations on order to get your hands on UNIX system. But smaller computers were being developed, and by end of the 80s, many people had home computers. By that time, there were several versions of UNIX available for the PC architecture, but none of them were truly free.

GNU Project/FSF

GNU project started in 1984 by Richard Mathew Stallman. Project goals were to create “free” UNIX clone, by 1990, nearly all required user space applications created and FSF stands for Free Software Foundation is non-profit organization that manages GNU project.

Philosophy

The term free software may have a different meaning than you expect. The term doesn’t refer to the cost of the software, but the fact that end user has the freedom to modify and change the program.

“Free software” refers to the users’ freedom to run, copy, distribute, study, change and improve the software. More precisely, it refers to four kinds of freedom, for the users of the software:

The freedom to run the program, for any purpose.
The freedom to study how the program works, and adapt it to your needs
The freedom to redistribute codes (software) so you can help your neighbor.
The freedom to improve program, and release your improvements to public, so that the whole community benefits.

Linus and Linux

Linus Torvalds, a young man studying computer science at the University of Helsinki, thought it would be a good idea to have some sort of freely available academic version of UNIX, and promptly stared to code.

He started to ask questions, looking for answers and solutions that would help him get UNIX on his PC.

From the start, it was Linus’ goal to have free system that was completely compliant with the original UNIX.

That is why he asked for POSIX standards, POSIX still being the standard for UNIX.

In those days plug-and-play wasn’t invented yet, but so many people were interested in having a UNIX system of their own, that was only a small obstacle. New drivers became available for all kind of new hardware, at a continuously rising speed. Almost as soon as new piece of hardware became available, someone bought it and submitted it to the Linux test, as the systems was gradually being called, releasing more free code for an ever wider range of hardware. These coders didn’t stop at their PC’s, every piece of hardware they could find was useful for Linux. Back then, those people were called “nerds” or “freaks”, but it didn’t matter to them, as long as the supported hardware list grew longer and longer. Thanks to these people, Linux is now not only ideal to run on new PC’s but it also the system of choice for old and exotic hardware that would be useless if Linux didn’t exist.

Introduction to Linux

Two years after Linus’ post, there were 12000 Linux users. The project, popular with hobbyists, grew steadily, all the while staying within the bounds of the POSIX standard. All the features of the UNIX were added over the next couple of years, resulting in the mature operating system Linux has become today. Linux is a full UNIX clone, fit for use on workstations s well as on middle-range and high-end servers. Today, all the important players on the hard and software market each have their team of Linux developers, at your local dealer’s you can even buy pre-installed Linux systems with official support.

Why Linux is better?

Cost -- Linux is free, and that includes all the apps. Microsoft is greedy. Vista Home Premium and Ultimate cost hundreds of dollars, even when upgrading from Windows XP. Moving up to Office 2007 involves handing over another bundle of dollars.
Resources -- Even the most lavishly equipped Linux distros demand no more resources than Windows XP. Vista is greedy: a single-user PC operating system that needs 2GB of RAM to run at acceptable speed, and 15GB of hard disk space, is grossly obese.
Performance -- Linux worked faster on my Dell Inspiron Core Duo than XP, at least the way XP worked out of the box. After cleaning out the bloatware and trading McAfee's Abrams Tank for the lightweight NOD32, XP and Linux (with Guarddog and Clam-AV) perform at similar speed.
No bloat ware -- Linux is free from adware, trialware, shovelware, and bloat ware. Running Linux is like watching the public TV network.
Security -- Last year, 48,000 new virus signatures were documented for Windows, compared to 40 for Linux. Still, most bistros come with firewalls and anti virus (AV) software. Programs like Guard dog and Clam-AV are free, of course.
Dual booting -- The best Linux distros make dual booting a simple affair, along with the required disk partitioning (so you don't need to buy partitioning software). Windows on my Dell laptop is still intact after installing and uninstalling a dozen distros.
Installation -- Anyone who's done it once knows that installing Windows from scratch takes hours or even days by the time you get all your apps up and running. With Linux, it can take as little as half an hour to install the operating system, utilities, and a full set of applications. No registration or activation is required, no paperwork, and no excruciating pack drill.
Reinstalling the OS -- You can't just download an updated version of Windows. You have to use the CD that came with your PC and download all the patches Microsoft has issued since the CD was made. With Linux, you simply download the latest version of your distro (no questions asked) and, assuming your data files live in a separate disk partition, there's no need to reinstall them. You only need to re-install the extra programs you added to the ones that came with the distro.
Keeping track of software -- Like most Windows users, I have a shelf full of software CDs and keep a little book with serial numbers under my bed in case I have to reinstall the lot. With Linux, there are no serial numbers or passwords to lose or worry about. Not a single one.
Updating software -- Linux updates all the software on your system whenever updates are available online, including all applications programs. Microsoft does that for Windows software but you have to update each program you've added from other sources. That's about 60 on each of my PCs. More icing on the Linux cake is that it doesn't ask you to reboot after updates. XP nags you every ten minutes until you curse and reboot your machine. If you choose "custom install" to select only the updates you want, XP hounds you like a mangy neighborhood dog until you give in.
More security -- These days, operating systems are less vulnerable than the applications that run on them. Therefore a vital aspect of PC security is keeping your apps up-to-date with the latest security patches. That's hard manual labor in Windows, but with Linux it's automatic.
No need to defrag disks -- Linux uses different file systems that don't need defragging. NTFS was going to be replaced in Vista, but Microsoft's new file system didn't make the final cut. Instead, Vista does scheduled disk defragging by default, but the defrag utility is a sad affair.
A wealth of built-in utilities -- The utilities supplied with Windows are pretty ordinary on the whole, that's why so many small software firms have made a nice living writing better ones. Linux programs are comparable with the best Windows freeware, from CD burners to photo managers, memory monitors and disk utilities. PDF conversion is built-in, both into OpenOffice Writer and into the DTP application Scribus. All you do is click a button on the task bar.