Basado en paquetes de RHEL v4 .. antes que nada debemos importar las llaves , como es logico como root :
rpm --import http://dag.wieers.com/packages/RPM-GPG-KEY.dag.txt
rpm --import http://dries.ulyssis.org/ayo/RPM-GPG-KEY.dries.txt
rpm --import http://freshrpms.net/packages/RPM-GPG-KEY.txt
y luego modificar o practicamente actualizar (copiar todo esto en el archivo yum.conf)
----------------------------------------------------------------------------------------
[main]
retries = 20
tolerant = 1
cachedir = /var/cache/yum
exactarch = 1
pkgpolicy = newest
distroverpkg = redhat-release
debuglevel = 2
logfile = /var/log/yum.log
[centos updates]
gpgcheck = True
enabled = 1
name = CenOS Updates
baseurl = http://mirror.centos.org/centos/4/updates/x86_64/
http://mirror.centos.org/centos/4/updates/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/updates/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/updates/x86_64/
[extras]
gpgcheck = True
name = CentOS-$releasever - extras
baseurl = http://beta.centos.org/centos/$releasever/extras/$basearch/
[dries]
gpgcheck = True
enabled = 0
name = Extra CentOS rpms dries - EL$releasever - $basearch
baseurl = http://apt.sw.be/dries/redhat/el4/en/x86_64/dries/
http://apt.sw.be/redhat/el4/en/x86_64/dag/
[dag]
name = Dag
enabled = 0
baseurl = http://dag.freshrpms.net/redhat/el4/en/$basearch/dag/
http = //ftp.heanet.ie/pub/freshrpms/pub/dag/redhat/el4/en/$basearch/dag/
gpgcheck = True
[jpackage-fedora]
name = JPackage CentOS Packages
failovermethod = priority
enabled = 0
baseurl = http://mirrors.sunsite.dk/jpackage/1.6/redhat-el-4.0/free
ftp://jpackage.hmdc.harvard.edu/JPackage/1.6/redhat-el-4.0/free
http://sunsite.informatik.rwth-aachen.de/ftp/pub/Linux/jpackage/redhat-el-4.0/free
gpgcheck = True
[centos base]
gpgcheck = True
enabled = 1
name = CenOS Base
baseurl = http://mirror.centos.org/centos/4/os/x86_64/
http://mirror.centos.org/centos/4/os/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/os/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/os/x86_64/
[dag apt]
gpgcheck = True
enabled = 1
name = Dag APT Repository
baseurl = http://dag.freshrpms.net/redhat/el4/en/x86_64/dag/
http://apt.sw.be/redhat/el4/en/x86_64/dag/
[flash]
gpgcheck = True
enabled = 0
name = macromedia.mplug.org - Flash Plugin
baseurl = http://macromedia.mplug.org/apt/redhat/4
http://sluglug.ucsc.edu/macromedia/apt/redhat/4
http://ruslug.rutgers.edu/macromedia/apt/redhat/4
http://macromedia.rediris.es/apt/redhat/4
[contrib]
gpgcheck = True
name = CentOS-$releasever - contrib
baseurl = http://beta.centos.org/centos/$releasever/contrib/$basearch/
[centos addons]
gpgcheck = True
enabled = 1
name = CenOS Addons
baseurl = http://mirror.centos.org/centos/4/addons/x86_64/
http://mirror.centos.org/centos/4/addons/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/addons/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/addons/x86_64/
[centos contrib]
gpgcheck = True
enabled = 1
name = CenOS Contrib
baseurl = http://mirror.centos.org/centos/4/contrib/x86_64/
http://mirror.centos.org/centos/4/contrib/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/contrib/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/contrib/x86_64/
[jpackage-generic]
name = JPackage Cross-Platform Packages
failovermethod = priority
enabled = 0
baseurl = http://mirrors.sunsite.dk/jpackage/1.6/generic/free
ftp://jpackage.hmdc.harvard.edu/JPackage/1.6/generic/free
http://sunsite.informatik.rwth-aachen.de/ftp/pub/Linux/jpackage/1.6/generic/free
gpgcheck = True
[base]
gpgcheck = True
name = CentOS-$releasever - Base
baseurl = http://beta.centos.org/centos/$releasever/os/$basearch/
[updates]
gpgcheck = True
name = CentOS-$releasever - Updates
baseurl = http://beta.centos.org/centos/$releasever/updates/$basearch/
[centos extras]
gpgcheck = True
enabled = 1
name = CenOS Extras
baseurl = http://mirror.centos.org/centos/4/extras/x86_64/
http://mirror.centos.org/centos/4/extras/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/extras/x86_64/
http://public.planetmirror.com/pub/caosity/centos/4/extras/x86_64/
[addons]
gpgcheck = True
name = CentOS-$releasever - addons
baseurl = http://beta.centos.org/centos/$releasever/addons/$basearch/