install yum centos 5

There is a simple way to install yum, even if you do not have the CD/DVD.
CENTOS 5 64 bits.
Just run

rpm -Uvh http://mirror.centos.org/centos/5/os/x86_64/CentOS/gmp-4.1.4-10.el5.x86_64.rpm
rpm -Uvh http://mirror.centos.org/centos/5/os/x86_64/CentOS/readline-5.1-3.el5.x86_64.rpm
rpm -Uvh 

Install Nagios on CentOS

Nagios 3 Quick Install on CentOS
This is short/fast HowTo Install Nagios 3 on CentOS/RedHat 5 64bits
::INSTALL NAGIOS::
rpm -Uhv http://apt.sw.be/redhat/el5/en/x86_64/rpmforge/RPMS//rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
yum update
vim /etc/selinux/config
SELINUX=disabled
reboot
yum -v …