1、由于centos6停止支持，官方把源移到了https://vault.centos.org/6.8/下，所以首先要更新源。

vim /etc/yum.repos.d/CentOS-Base.repo

将里面那几个baseurl中的mirror.centos.org改为vault.centos.org，如下：

[base]
name=CentOS-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
baseurl=http://vault.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#released updates 
[updates]
name=CentOS-$releasever - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
baseurl=http://vault.centos.org/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
baseurl=http://vault.centos.org/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib&infra=$infra
#baseurl=http://mirror.centos.org/centos/$releasever/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

修改epel.repo

vim /etc/yum.repos.d/epel.repo

改为如下

[epel]
name=Extra Packages for Enterprise Linux 6 - $basearch
baseurl=http://archives.fedoraproject.org/pub/archive/epel/6.2017-11-07/$basearch
#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch
failovermethod=priority
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6

[epel-debuginfo]
name=Extra Packages for Enterprise Linux 6 - $basearch - Debug
baseurl=https://archives.fedoraproject.org/pub/epel/6/$basearch/debug
#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-debug-6&arch=$basearch
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
gpgcheck=1

[epel-source]
name=Extra Packages for Enterprise Linux 6 - $basearch - Source
baseurl=https://archives.fedoraproject.org/pub/epel/6/SRPMS
#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-source-6&arch=$basearch
failovermethod=priority
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
gpgcheck=1

2、配置CentOS 6.0 第三方yum源（CentOS默认的标准源里没有nginx软件包）

wget http://www.atomicorp.com/installers/atomic
sh ./atomic
yum check-update

如果执行 yum check-update 报下面链接中的错误，则按照链接中的方法解决并重新执行 yum check-update
14Peer cert cannot be verified or peer cert invalid
thread.error: can't start new thread

3、安装并启动nginx(加入开机启动)

yum install nginx
service nginx start
chkconfig nginx on

[备注]
如果提示安装提示 No package nginx available 只需要去 http://fedoraproject.org/wiki/EPEL 下载epel安装既可，如下：

wget http://mirrors.sohu.com/fedora-epel/epel-release-latest-6.noarch.rpm
rpm -ivh rpm -ivh epel-release-latest-6.noarch.rpm

[扩展]
Nginx负载均衡-分布式/热备Web Server的搭建：
http://blog.csdn.net/jhq0113/article/details/44278221