How to install Nagios on CentOS?

Installing DAG’s Repo

I am using Dag’s repo (rpmforge) for installation via yum but source is available on http://www.nagios.org if you prefer to build from source.

Download Dag’s repo:

For i386:
rpm -Uhv http://apt.sw.be/redhat/el5/en/i386/rpmforge/RPMS/rpmforge-release-0.3.6-1.el5.rf.i386.rpm

For x86_64:
rpm -Uhv http://apt.sw.be/redhat/el5/en/x86_64/rpmforge/RPMS//rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm

Details of Dag’s repo can be found at http://dag.wieers.com/rpm/FAQ.php#B