自己参考了系统优化的点，写了一个一键优化脚本，适用于centos6.x版本，各个项已经单独进行测试通过。适用于centos6.x系统最小化安装执行，可以根据自己的需求进行添加或修改完善。
主要优化内容有：
关闭系统不必要的服务；关闭selinux，关闭iptables；关闭ctrl+alt+del重启；设置ssh端口，关闭DNS解析；设置系统最大文件描述符；设置系统关键文件权限；配置安装ntp；安装vim；配置安装阿里云yum源和epel源；
脚本如下：
[root@localhost ~]# cat youhua.sh
#!/bin/bash
#written by mofansheng@2015-11-03
#system optimization script
#The fllow apply to CentOS 6.x
. /etc/init.d/functions
function check_ok(){
if [ $? -eq 0 ]
then
echo ""
continue
else
echo "pls check error"
exit
fi
}
cat<<EOF
-----------------------------------------------------------------------
| system optimization |
-----------------------------------------------------------------------
EOF
#close unimportant system services
echo "===Close unimportant system services,it will take serval mintinues==="
for s in `chkconfig --list|grep 3:on|awk '{print $1}'|grep -Ev "crond|sshd|sysstat|rsyslog|network"`
do
chkconfig $s off
done
check_ok
action "Close unimportant system services" /bin/true
#close selinux
echo "===close SELINUX==="
if [ `getenforce` != "Disabled" ]
then
sed -i 's/SELINUX=enforcing/SELINUX=disabled/g' /etc/selinux/config
echo "selinux is disabled,you must reboot!"
else
action "SELINUX is closed" /bin/true
fi
check_ok
action "Close SELINUX" /bin/true
#close ctrl+alt+del
mv /etc/init/control-alt-delete.conf /etc/init/control-alt-delete.conf.bak
#close iptables
echo "===close iptables==="
iptables-save >/etc/sysconfig/iptables_$(date +%s)
iptables -F
service iptables save
check_ok
action "iptables is closed" /bin/true
#set ulimit
echo "ulimit -SHn 65535" >>/etc/rc.local
#set SSH
sed -i 's/#UseDNS yes/UseDNS no/g' /etc/ssh/sshd_config
sed -i 's/#Port 22/Port 65500/g' /etc/ssh/sshd_config
service sshd restart
#set system files permission
chmod 600 /etc/passwd
chmod 600 /etc/group
chmod 600 /etc/shadow
chmod 600 /etc/gshadow
#set ntp
yum install ntpdate -y
ntpdate ntp.fudan.edu.cn
echo "* 3 * * * /usr/sbin/ntpdate ntp.fudan.edu.cn >/dev/null 2>&1" >>/etc/crontab
service crond restart
check_ok
action "ntpdate is installed and add in crontab" /bin/true
#set vim
echo "===install vim,it will take serval mintinues==="
yum install vim-enhanced -y &>/dev/null
alias vi=vim
echo "alias vi=vim" >>/root/.bashrc
check_ok
action "vim is installed" /bin/true
#set yum repos
echo "===update yum repos,it will take serval mintinues==="
yum install wget -y
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo &>/dev/null
wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo &>/dev/null
yum clean all &>/dev/null
yum makecache &>/dev/null
check_ok
action "yum repos update is ok" /bin/true
