Nagios is an awesome Open Source monitoring tool, its provides you more comprehensive monitoring environment to always keep an eye on your all machines / networks whether you are in a your data center or just your small labs.
With Nagios, you can monitor your remote hosts and their services remotely on a single window. It shows warnings and indicates if something goes wrong in your servers which eventually helps us to detect some problems before they occur. It helps us to reduce downtime and business losses.
Download Nagios:
nagios-4.2.4.tar.gz
nagios-plugins-2.2.1.tar.gz
nrpe-2.13.tar.gz
## Create nagios user, add nagios and web server users to the nagios group adduser nagios mkdir /usr/local/nagios chown nagios.nagios /usr/local/nagios /usr/sbin/groupadd nagcmd /usr/sbin/usermod -G nagcmd daemon /usr/sbin/usermod -G nagcmd nagios /usr/sbin/usermod -G nagcmd [APACHE USER] /usr/sbin/usermod -G nagcmd nagios
./configure --prefix=/usr/local/nagios --with-cgiurl=/nagios/cgi-bin --with-htmurl=/nagios --with-nagios-user=nagios --with-nagios-group=nagios --with-command-group=nagcmd make all make install make install-init make install-commandmode make install-config make install-webconf
Include Ngios config file to apache
ll /etc/httpd/conf.d/ mv /etc/httpd/conf.d/nagios.conf /usr/local/apache2/conf/extra/ vim /usr/local/apache2/conf/httpd.conf
go to the bottom of the page and insert as below
# Nagios Configuration Include c/etc/httpd/conf.d/nagios.conf
Create password for “nagiosadmin” user
htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin
Restart apache and start nagios
service httpd restart service nagios restart
Install Nagios Plugins
tar xzf nagios-plugins-2.2.1.tar.gz cd nagios-plugins-2.2.1 ./configure make make install chown -R nagios.nagios /usr/local/nagios/libexec
Set auto start to nagios and apache services
chkconfig --list | grep httpd chkconfig --level 345 httpd on chkconfig --list | grep nagios chkconfig --add nagios chkconfig --list | grep nagios
usermod -a -G nagios apache – [mks_highlight color=”#81d742″]permanent fix for Error: Could not open command file ‘/usr/local/nagios/var/rw/nagios.cmd’ for update![/mks_highlight]
Installing Plugins and NRPE on Remote Linux Host
adduser nagios tar -xzf nagios-plugins-1.4.6.tar.gz cd nagios-plugins-1.4.6 ./configure make make install chown nagios.nagios /usr/local/nagios chown -R nagios.nagios /usr/local/nagios/libexec
Installing NRPE without xinetd on Nagios Host and Remote Host
./configure --enable-ssl make all make install-plugin make install-daemon make install-daemon-config install init-script /etc/init.d/nrpe
Configure NRPE
#vim /usr/local/nagios/etc/nrpe.cfg
allowed_hosts=127.0.0.1,,
#/etc/init.d/nrpe start
#vim /etc/services
nrpe 5666/tcp # NRPE
#chkconfig --list | grep nrpe
#chkconfig --add nrpe
#chkconfig --list | grep nrpe
===check nrpe===
#/usr/local/nagios/libexec/check_nrpe -H localhost
#/usr/local/nagios/libexec/check_nrpe -H
===Allow NRPE from IPtables====
-A RH-Firewall-1-INPUT -m state --state NEW -m tcp -p tcp --dport 5666 -j ACCEPT
===Add check_nrpe command to commands.cfg====
vi /usr/local/nagios/etc/commands.cfg
define command{
command_name check_nrpe
command_line $USER1$/check_nrpe -H $HOSTADDRESS$ -c $ARG1$
}
Veryfing nagios config
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
Enable external cgi commnds
#vim /usr/local/nagios/etc/cgi.cfg authorized_for_all_service_commands=nagiosadmin authorized_for_all_host_commands=nagiosadmin #vim /usr/local/nagios/etc/nagios.cfg check_external_commands=1
