How to Install Nagios 3 on Ubuntu 8.10

Nagios is a free, open-source tool that can be used to monitor network components and services.Â When it detects a problem, it can send alert messages by either e-mail or pager.Â It can also be configured so that only designated personnel can view status information for particular services or equipment.Â This tutorial will show you how to install Nagios 3 on an Ubuntu 8.10 server.

Installation

Nagios3 is in the repository for Ubuntu 8.10.

sudo apt-get install nagios3

You can see that it will install a number of packages to make it all work.
The following extra packages will be installed:
libfreetype6 libgd2-noxpm libjpeg62 libnet-snmp-perl libperl5.10 libpng12-0
libradius1 libsensors3 libsnmp-base libsnmp15 libsysfs2 libtalloc1
libwbclient0 nagios-images nagios-plugins nagios-plugins-basic
nagios-plugins-standard nagios3-common nagios3-doc radiusclient1
samba-common smbclient snmp
Suggested packages:
libfreetype6-dev libgd-tools libcrypt-des-perl libdigest-hmac-perl
libdigest-sha1-perl libio-socket-inet6-perl lm-sensors nagios2 nagios-text
nagios whois nagios-nrpe-plugin smbfs
The following NEW packages will be installed:
libfreetype6 libgd2-noxpm libjpeg62 libnet-snmp-perl libperl5.10 libpng12-0
libradius1 libsensors3 libsnmp-base libsnmp15 libsysfs2 libtalloc1
libwbclient0 nagios-images nagios-plugins nagios-plugins-basic
nagios-plugins-standard nagios3 nagios3-common nagios3-doc radiusclient1
samba-common smbclient snmp
0 upgraded, 24 newly installed, 0 to remove and 0 not upgraded.
Need to get 19.5MB of archives.
After this operation, 54.6MB of additional disk space will be used.

Once it is installed run a pre-flight check to verify it is working correctly.

Pre-Flight Check
sudo nagios3 -v nagios.cfg

Nagios 3.0.2
Copyright (c) 1999-2008 Ethan Galstad (http://www.nagios.org)
Last Modified: 05-19-2008
License: GPL

Reading configuration dataâ€¦

Running pre-flight check on configuration dataâ€¦

Checking servicesâ€¦
Checked 7 services.
Checking hostsâ€¦
Checked 2 hosts.
Checking host groupsâ€¦
Checked 5 host groups.
Checking service groupsâ€¦
Checked 0 service groups.
Checking contactsâ€¦
Checked 1 contacts.
Checking contact groupsâ€¦
Checked 1 contact groups.
Checking service escalationsâ€¦
Checked 0 service escalations.
Checking service dependenciesâ€¦
Checked 0 service dependencies.
Checking host escalationsâ€¦
Checked 0 host escalations.
Checking host dependenciesâ€¦
Checked 0 host dependencies.
Checking commandsâ€¦
Checked 142 commands.
Checking time periodsâ€¦
Checked 4 time periods.
Checking for circular paths between hostsâ€¦
Checking for circular host and service dependenciesâ€¦
Checking global event handlersâ€¦
Checking obsessive compulsive processor commandsâ€¦
Checking misc settingsâ€¦

Total Warnings: 0
Total Errors:Â Â 0

Things look okay – No serious problems were detected during the pre-flight check

By default it should run and you should be able to login to the web interface after you create the nagios user.Â Move into the /etc/nagios3 directory and create a user to access the web interface.

htpasswd -c htpasswd.users nagios
New password:
Re-type new password:
Adding password for user nagios

Now login to the web interface with http://ip_address/nagios3

You will not have all of the rights to view everything but for the purposes of making sure it all works you will see it is all running.Â Â Now you need to configure it for your settings.

Basic ConfigurationÂ
The configuration is where you will get to setÂ up the services and hosts that you need.

Now, cd to the /etc/nagios3 directory.

cd /etc/nagios3

Here you will see the base file nagios.cfg.Â The additional configuration files are located in conf.d.

contacts_nagios2.cfgÂ Â Â Â Â Â Â Â generic-service_nagios2.cfgÂ Â Â Â localhost_nagios2.cfg
extinfo_nagios2.cfgÂ Â Â Â Â Â Â Â Â host-gateway_nagios3.cfgÂ Â Â Â Â Â Â services_nagios2.cfg
generic-host_nagios2.cfgÂ Â Â Â hostgroups_nagios2.cfgÂ Â Â Â Â Â Â Â Â timeperiods_nagios2.cfg

Check the â€œtimeperiods_nagios2.cfgâ€ file to define different time periods for when you want certain functions to happen.Â Hereâ€™s an example:

# Time periods
# All times are valid for all
# checks and notifications

define timeperiod{
timeperiod_name 24Ã—7
aliasÂ Â Â Â Â Â Â Â Â Â Â Â Â 24 Hours A Day, 7 Days A Week
sundayÂ Â Â Â Â Â Â Â Â 00:00-24:00
mondayÂ Â Â Â Â Â Â 00:00-24:00
tuesdayÂ Â Â Â Â Â Â Â 00:00-24:00
wednesdayÂ Â Â 00:00-24:00
thursdayÂ Â Â Â Â Â Â 00:00-24:00
fridayÂ Â Â Â Â Â Â Â Â Â Â 00:00-24:00
saturdayÂ Â Â Â Â Â Â 00:00-24:00
}

define timeperiod{
timeperiod_name 8Ã—5
aliasÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â 8 Hours A Day, 5 Days A Week
mondayÂ Â Â Â Â Â Â Â Â 08:00-16:00
tuesdayÂ Â Â Â Â Â Â Â Â Â 08:00-16:00
wednesdayÂ Â Â Â 08:00-16:00
thursdayÂ Â Â Â Â Â Â Â 08:00-16:00
fridayÂ Â Â Â Â Â Â Â Â Â Â Â 08:00-16:00
}

Check,Â the â€œcontacts_nagios2.cfgâ€ file.Â This will define the types of notifications that individuals and groups will receive, and when they will be contacted.

# Contactsâ€“Individuals and Groups

define contact{
contact_nameÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â fred
aliasÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Nagios Admin
service_notification_periodÂ Â Â Â Â Â Â Â Â 24Ã—7
host_notification_periodÂ Â Â Â Â Â Â Â Â Â Â Â Â Â 24Ã—7
service_notification_optionsÂ Â Â Â Â Â Â w,u,c,r
host_notification_optionsÂ Â Â Â Â Â Â Â Â Â Â Â Â d,r
service_notification_commandsÂ Â Â notify-by-email
host_notification_commandsÂ Â Â Â Â Â Â Â host-notify-by-email
emailÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â fred.smith@some_mail.net
}

The email account that you add for the Nagios Admin should be your main email account as this will be used to send you information.

# contact groups
# Nagios only talks to contact groups, not individuals
# Members must be Nagios users, alias and contact_group
# are whatever you want

define contactgroup{
contactgroup_nameÂ Â Â Â Â Â Â Â Â Â Â Â Â Â admins
aliasÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Nagios Administrators
membersÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â fred
}

In this file, each person who is to be a contact must have his own â€œdefine contactâ€ section.Â Each person must also be a member of a â€œcontactgroupâ€.Â Also, each person who is to be a contact must have a system account on the Nagios server, have a Nagios password, and be a member of the â€œnagiosâ€ group.Â (This group will be created automatically when you install Nagios.)

useradd -m -G nagios fred
passwd fred

If you havenâ€™t yet created the Nagios password database, youâ€™ll use the â€œhtpasswdâ€ command with the -c option to create the new file.

htpasswd -c /etc/nagios/htpasswd.users nagios

If the database has already been created, and you just want to add a new user to it, then omit the -c option:

Â Now you should be able to see the host that you set up for an example and see that it is monitoring.Â You are ready to begin the next phase of setting up a loto of hosts and services to monitor