yum源更新后需要导入key值，否则报错如下，无法安装相关的包。
Totalsize:42M
DownloadingPackages:
warning:rpmts_HdrFromFdno:HeaderV3RSA/SHA1Signature,keyIDc105b9de:NOKEY
Retrievingkeyfromfile:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
GPGkeyretrievalfailed:[Errno14]Couldnotopen/readfile:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
解决办法：
先安装如下工具包：
rpm-Uhvhttp://dag.wieers.com/packages/rpmforge-release/rpmforge-release-0.3.4-1.el4.rf.i386.rpm
[root@localhostyum.repos.d]#rpm--import/etc/pki/rpm-gpg/RPM-GPG-KEY-6
一般来说安装完成后即可，安装完这个就可以了。
如果还是不行，查看系统的
编辑yum源文件：替换RPM-GPG-KEY-CentOS-5替换为对应的key文件名：RPM-GPG-KEY-CentOS-6（要全部替换）
root@localhostyum.repos.d]#viCentOS-Base-sohu.repo
[base]
name=CentOS-$releasever-Base-sohu.com
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
baseurl=http://mirrors.sohu.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
author gj