12. January 2013 · Comments Off on How to install nagios in rhel 6.3 / centos 6.3 · Categories: Linux · Tags: , ,
This guide is intended to provide you with simple instructions on how to install Nagios from source (code) on Fedora and have it monitoring your local machine inside of 20 minutes. No advanced installation options are discussed here – just the basics that will work for 95% of users who want to get started.
These instructions were written based on a standard RHEL 6.3 Linux distribution.
What You’ll End Up With
 
If you follow these instructions, here’s what you’ll end up with:
  • Nagios and the plugins will be installed underneath /usr/local/nagios
  • Nagios will be configured to monitor a few aspects of your local system (CPU load, disk usage, etc.)
  • The Nagios web interface will be accessible at http://localhost/nagios/
Prerequisites
 
During portions of the installation you’ll need to have root access to your machine.
Make sure you’ve installed the following packages on your Fedora installation before continuing.
  • Apache
  • PHP
  • GCC compiler
  • GD development libraries
You can use yum to install these packages by running the following commands (as root):
yum install httpd php

yum install gcc glibc glibc-common

yum install gd gd-devel
gd-devel is not available in default package so download from here.
While installing it throws dependency errors.
Just install those dependency through yum after that install this gd-devel rpm
ftp://rpmfind.net/linux/centos/6.3/os/x86_64/Packages/gd-devel-2.0.35-10.el6.x86_64.rpm

1) Create Account Information
Become the root user.
su -l
Create a new nagios user account and give it a password.
/usr/sbin/useradd -m nagios

passwd nagios
Create a new nagcmd group for allowing external commands to be submitted through the web interface. Add both the nagios user and the apache user to the group.
/usr/sbin/groupadd nagcmd

/usr/sbin/usermod -a -G nagcmd nagios

/usr/sbin/usermod -a -G nagcmd apache

2) Download Nagios and the Plugins
Create a directory for storing the downloads.
mkdir ~/downloads

cd ~/downloads
Download the source code tarballs of both Nagios and the Nagios plugins (visit http://www.nagios.org/download/ for links to the latest versions).

3) Compile and Install Nagios

Extract the Nagios source code tarball.
cd ~/downloads

tar xzf nagios-3.2.3.tar.gz

cd nagios-3.2.3
Run the Nagios configure script, passing the name of the group you created earlier like so:
./configure --with-command-group=nagcmd
Compile the Nagios source code.
make all
Install binaries, init script, sample config files and set permissions on the external command directory.
make install

make install-init

make install-config

make install-commandmode
Don’t start Nagios yet – there’s still more that needs to be done…
4) Customize Configuration
Sample configuration files have now been installed in the /usr/local/nagios/etc directory. These sample files should work fine for getting started with Nagios. You’ll need to make just one change before you proceed…
Edit the /usr/local/nagios/etc/objects/contacts.cfg config file with your favorite editor and change the email address associated with the nagiosadmin contact definition to the address you’d like to use for receiving alerts.

vi /usr/local/nagios/etc/objects/contacts.cfg
5) Configure the Web Interface
Install the Nagios web config file in the Apache conf.d directory.

make install-webconf
Create a nagiosadmin account for logging into the Nagios web interface. Remember the password you assign to this account – you’ll need it later.
htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
Restart Apache to make the new settings take effect.

service httpd restart

Note: Consider implementing the ehanced CGI security measures described here
to ensure that your web authentication credentials are not compromised.

[root@station1 ~]# htdigest -c /usr/local/nagios/etc/.digest_pw "Nagios Access" 
nagiosadmin

Adding password for nagiosadmin in realm Nagios Access.
New password: 
Re-type new password:

[root@station1 ~]# vim /etc/httpd/conf.d/nagios.conf 
  9 ScriptAlias /nagios/cgi-bin "/usr/local/nagios/sbin"
 10 
 11 <Directory "/usr/local/nagios/sbin">
 12    SSLRequireSSL
 13    Options ExecCGI
 14    AllowOverride None
 15    Order allow,deny
 16 #   Allow from all
 17 #  Order deny,allow
 18 #  Deny from all
 19    Allow from 127.0.0.1 10.65.62.30
 20    AuthName "Nagios Access"
 21    AuthType Digest
 22    AuthUserFile /usr/local/nagios/etc/.digest_pw
 23    Require valid-user
 24 </Directory>
 25 
 26 Alias /nagios "/usr/local/nagios/share"
 27 
 28 <Directory "/usr/local/nagios/share">
 29    SSLRequireSSL
 30    Options None
 31    AllowOverride None
 32    Order allow,deny
 33 #   Allow from all
 34 #  Order deny,allow
 35 #  Deny from all
 36    Allow from 127.0.0.1 10.65.62.30
 37    AuthName "Nagios Access"
 38    AuthType Digest
 39    AuthUserFile /usr/local/nagios/etc/.digest_pw
 40    Require valid-user
 41 </Directory>

6) Compile and Install the Nagios Plugins
Extract the Nagios plugins source code tarball.
cd ~/downloads

tar xzf nagios-plugins-1.4.11.tar.gz

cd nagios-plugins-1.4.11
Compile and install the plugins.

./configure --with-nagios-user=nagios --with-nagios-group=nagios

make

make install
7) Start Nagios
Add Nagios to the list of system services and have it automatically
start when the system boots.

chkconfig --add nagios

chkconfig nagios on
Verify the sample Nagios configuration files.

/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
If there are no errors, start Nagios.

service nagios start
8) Modify SELinux Settings
Fedora ships with SELinux (Security Enhanced Linux) installed and in Enforcing mode by default. This can result in “Internal Server Error” messages when you attempt to access the Nagios CGIs.
See if SELinux is in Enforcing mode.
getenforce
Put SELinux into Permissive mode.
setenforce 0
To make this change permanent, you’ll have to modify the settings in /etc/selinux/config and reboot.
Instead of disabling SELinux or setting it to permissive mode, you can use the following command to run the CGIs under SELinux enforcing/targeted mode:
chcon -R -t httpd_sys_content_t /usr/local/nagios/sbin/

chcon -R -t httpd_sys_content_t /usr/local/nagios/share/
For information on running the Nagios CGIs under Enforcing mode with a targeted policy, visit the Nagios Support Portal or Nagios Community Wiki.
9) Login to the Web Interface
You should now be able to access the Nagios web interface at the URL below. You’ll be prompted for the username (nagiosadmin) and password you specified earlier.

http://localhost/nagios/
Click on the “Service Detail” navbar link to see details of what’s being monitored on your local machine. It will take a few minutes for Nagios to check all the services associated with your machine, as the checks are spread out over time.
10) Other Modifications
Make sure your machine’s firewall rules are configured to allow access to the web server if you want to access the Nagios interface remotely.
Configuring email notifications is out of the scope of this documentation. While Nagios is currently configured to send you email notifications, your system may not yet have a mail program properly installed or configured. Refer to your system documentation, search the web, or look to the Nagios Support Portal or Nagios Community Wiki for specific instructions on configuring your system to send email messages to external addresses. More information on notifications can be found here.
11) You’re Done
Congratulations! You sucessfully installed Nagios.

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