yum install nc

报错如下：

Loaded plugins: fastestmirror, product-id, subscription-manager

This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.

Setting up Install Process

No package nc available.

Error: Nothing to do

解决方法：

rpm -qa | grep yum | xargs rpm -e --nodeps

下载附件中的rpm包

rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm

rpm -ivh yum-*

更新/etc/yum.repos.d/rhel-source.repo的内容为如下：

# CentOS-Base.repo

#

# The mirror system uses the connecting IP address of the client and the

# update status of each mirror to pick mirrors that are updated to and

# geographically close to the client.  You should use this for CentOS updates

# unless you are manually picking other mirrors.

#

# If the mirrorlist= does not work for you, as a fall back you can try the

# remarked out baseurl= line instead.

#

#

[base]

name=CentOS-6 - Base - sankuai.com

baseurl=http://mirrors.sankuai.com/centos/6/os/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=os

gpgcheck=1

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#released updates

[updates]

name=CentOS-6 - Updates - sankuai.com

baseurl=http://mirrors.sankuai.com/centos/6/updates/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=updates

gpgcheck=1

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#additional packages that may be useful

[extras]

name=CentOS-6 - Extras - sankuai.com

baseurl=http://mirrors.sankuai.com/centos/6/extras/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=extras

gpgcheck=1

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#additional packages that extend functionality of existing packages

[centosplus]

name=CentOS-6 - Plus - sankuai.com

baseurl=http://mirrors.sankuai.com/centos/6/centosplus/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=centosplus

gpgcheck=1

enabled=0

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#contrib - packages by Centos Users

[contrib]

name=CentOS-6 - Contrib - sankuai.com

baseurl=http://mirrors.sankuai.com/centos/6/contrib/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=contrib

gpgcheck=1

enabled=0

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6