Category: Linux

Yes you can Monitor Websites and Web Services Live for Free from PC Using Nagios. Nagios is a host and service monitoring tool  designed to inform network problems. When problems are encountered, the Nagios daemon can send notifications out to you in a variety of different ways (email, instant message,  etc.). Current status information, historical logs, and reports can all be accessed via a web browser too.

Features of Nagios include Monitoring of network services like SMTP, POP3, HTTP, IMAP, PING, FTP, etc. This features also can be used to monitor your websites which are hosted in third party hosting servers, that’s especially from home/office PC itself!!

Setting up Nagios for your domains:

1) Installation process

You can use following commands to install components needed.

• Installing Apache/httpd and Nagios under Fedroa Core/Cent OS Linux

# yum install httpd
# chkconfig httpd on
# /etc/init.d/httpd start
# yum install nagios nagios-plugins nagios-plugins-all

• Debian, Ubuntu Linux httpd/Apache and Nagios installation

# apt-get install apache2
# /etc/init.d/apache2 start
# apt-get install nagios-text nagios-plugins nagios-images
or
# apt-get install nagios2 nagios-plugins nagios-images

• If you don’t have yum/apt. Install stable apache/nagios by downloading from following sites

Apache:- http://httpd.apache.org/
Nagios:- http://www.nagios.org/download/#stable

Now we done with Installation next….
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2) Configuring Nagios:

• Add a custom directory for your *.cfg files

# mkdir /etc/nagios2/mysite

• Edit /etc/nagios2/nagios.cfg and edit the following path

Default path cfg_dir=/etc/nagios2/conf.d to
cfg_dir=/etc/nagios2/mysite

• Create your own configuration files inside the defined directory that is In /etc/nagios2/mysite; add the following files.

– contacts.cfg: Defines the people who will receive the alerts in case of a problem.
Here you need to change e-mail ID and Pager ID.

define contact{
contact_name                    Admin
alias                           Administrator Name
service_notification_period     24×7
host_notification_period        24×7
service_notification_options    w,u,c,r
host_notification_options       d,u,r
service_notification_commands   notify-by-email,notify-by-pager
host_notification_commands      host-notify-by-email,host-notify-by-epager
email                           admin@yourdomain.com
pager                           11111111@pager.yourdomain.com
}

define contactgroup{
contactgroup_name       admins
alias                   Nagios Administrators
members                 Admin # contact_name should be added here
}

– host.cfg: Defines the url’s that will be monitored.

##You can add as many as url’s need like bellow
define host{
host_name  jithesh.com
alias      Jithesh
address    www.jithesh.com
use        generic-host
}

define host{
host_name  blog.jithonline.com
alias      JithOnline
address    blog.jithonline.com
use        generic-host
}

#### Hostgroup_name ###
define hostgroup {
hostgroup_name  all
alias           All Servers
members         *
}

# A list of your servers
define hostgroup {
hostgroup_name    servers
alias           Servers
members         jithesh.com, blog.jithonline.com  #Add all host_name here
}

– services.cfg: Defines the services that will be monitored for each URL.

## Hostgroups services ##
define service {
hostgroup_name                 servers
service_description             HTTP
check_command                 check_http
use                             generic-service
notification_interval           0
}

define service {
hostgroup_name                 servers
service_description             PING
check_command                 check_ping!100.0,20%!500.0,60%
use                             generic-service
notification_interval           0
}

define service {
hostgroup_name                 servers
service_description             FTP
check_command                 check_ftp
use                             generic-service
notification_interval           0
}

define service {
hostgroup_name                 servers
service_description             POP
check_command                 check_pop
use                             generic-service
notification_interval           0
}

define service {
hostgroup_name                 servers
service_description             IMAP
check_command                 check_imap
use                             generic-service
notification_interval           0
}

define service {
hostgroup_name                 servers
service_description             SMTP
check_command                 check_smtp
use                             generic-service
notification_interval           0
}

– templates.cfg: Defines some templates like the generic url, generic service and a lot of others custom templates.

In the default installation you will find files named generic-host_nagios2.cfg, generic-service_nagios2.cfg and there might be others. Just with copy and paste them into /etc/nagios2/mysite directory it will work OK. Anyway, I prefer to put the definitions on each of them into a single file called templates.cfg, but that’s a personal preference.

– timeperiods.cfg: Defines time periods which are valid for checks, notifications, etc.

The default configuration file is OK, so just copy and paste it from /etc/nagios2/conf.d/timeperiods_nagios2.cfg to /etc/nagios2/mysite/timeperiods.cfg.

So we have done with all configuration stuffs.

3)  Restart the Nagios service:

# /etc/init.d/nagios2 restart
If there is any configuration error Nagios will tell you where it is when you attempt to restart the service.

4) Monitor your URLs

By opening Nagios in browser
http://<nagios_server_host>/nagios2
user name:-nagiosadmin
passwd:-<set passwd> Most of the case root passwd itself

If you still having problems, don’t hesitate to post comment.