国外服务器有的不能直接访问到163的CentOS源，搞了很久才搞定，下面贴出具体方法：
1.进入/etc/yum.repos.d，新建文件mirrors-rpmforge，然后写入以下地址:
http://apt.sw.be/RedHat/el5/en/$ARCH/dag
http://archive.cs.uu.nl/mirror/dag.wieers/redhat/el5/en/$ARCH/dag
http://ftp2.lcpe.uni-sofia.bg/freshrpms/pub/dag/redhat/el5/en/$ARCH/dag
#http://ftp.heanet.ie/pub/freshrpms/pub/dag/redhat/el5/en/$ARCH/dag
http://ftp-stud.fht-esslingen.de/dag/redhat/el5/en/$ARCH/dag
http://mirror.cpsc.ucalgary.ca/mirror/dag/redhat/el5/en/$ARCH/dag
http://mirrors.ircam.fr/pub/dag/redhat/el5/en/$ARCH/dag
http://rh-mirror.linux.iastate.edu/pub/dag/redhat/el5/en/$ARCH/dag
http://rpmfind.net/linux/dag/redhat/el5/en/$ARCH/dag
http://wftp.tu-chemnitz.de/pub/linux/dag/redhat/el5/en/$ARCH/dag
http://www.mirrorservice.org/sites/apt.sw.be/redhat/el5/en/$ARCH/dag
2.新建文件rpmforge.repo,然后写入以下内容:
# Name: RPMforge RPM Repository for Red Hat Enterprise 5 - dag
# URL: http://rpmforge.net/
[rpmforge]
name = Red Hat Enterprise $releasever - RPMforge.net - dag
#baseurl = http://apt.sw.be/redhat/el5/en/$basearch/dag
mirrorlist = http://apt.sw.be/redhat/el5/en/mirrors-rpmforge
#mirrorlist = file:///etc/yum.repos.d/mirrors-rpmforge
enabled = 1
protect = 0
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
gpgcheck = 1
3.修改这2个文件权限，先执行一下rpm --import http://apt.sw.be/RPM-GPG-KEY.dag.txt注册RPM-GPG-KEY.dag，最后测试一下，执行yum clean all
4.这样就可以直接更新到这些新源了，然后执行yum search rz试试，等全部更新完就OK了
5.CentOS5和CentOS6均成功。