The default RPMforge repository does not replace any  CentOS base packages. In the past it used to, but those packages are now  in a separate repository (rpmforge-extras) which is disabled by  default. 
You can find a complete listing of the RPMforge package packages at http://packages.sw.be/  
Download the rpmforge-release  package.  Choose one of the two links below, selecting to match your  host's architecture.  If you are unsure of which one to use you can  check your architecture with the command uname -i 
The preferred rpmforge-release package to retrieve and to install in order to enable that repository is one of the two listed above. 
Install DAG's GPG key 
rpm --import http://apt.sw.be/RPM-GPG-KEY.dag.txt
Verify the package you have downloaded 
rpm -K rpmforge-release-0.5.2-2.el5.rf.*.rpm
Install the package 
rpm -i rpmforge-release-0.5.2-2.el5.rf.*.rpm
This will add a yum repository config file and import the appropriate GPG keys. 
Then try to install something like this 
yum install htop
 
 
[dag]
ตอบลบname=Dag RPM Repository for Red Hat Enterprise Linux
baseurl=http://apt.sw.be/redhat/el$releasever/en/$basearch/dag
gpgcheck=1
enabled=1