1.关闭selinux
sed -i 's#SELINUX=enforcing#SELINUX=disabled#g' /etc/selinux/config
setenforce 0 临时生效，想要长期生效，重启系统
getenforce 查看selinux状态
2.关闭防火墙
/etc/init.d/iptables stop
/etc/init.d/iptables stop 要关闭至少2次
chkconfig iptables off
3.精简开机自启动服务
chkconfig|egrep -v "crond|sshd|network|rsyslog|sysstat"|awk '{print "chkconfig",$1,"off"}'|bash
export LANG=en
chkconfig --list|grep 3:on

4.提权oldboy可以sudo
useradd oldboy
\cp /etc/sudoers /etc/sudoers.ori
echo "oldboy ALL=(ALL) NOPASSWD:ALL">>/etc/sudoers
tail -l /etc/sudoers
visudo -c

5.中文字符集
先查看
[root@oldboy ~]# cat /etc/sysconfig/i18n
LANG="en_US.UTF-8"
SYSFONT="latarcyrheb-sun16"
再备份
[root@oldboy ~]# cp /etc/sysconfig/i18n /etc/sysconfig/i18n.ori
再修改
[root@oldboy ~]# echo 'LANG="zh_CN.UTF-8"'>/etc/sysconfig/i18n
[root@oldboy ~]# source /etc/sysconfig/i18n
#使上文修改生效
[root@oldboy ~]# echo $LANG
查看当前字符集状态

6.时间同步
[root@oldboy ~]# echo '#time sync by oldboy at 2010-2-1'>>/var/spool/cron/root
[root@oldboy ~]# echo '*/5 * * * * /usr/sbin/ntpdate time.nist.gov >/dev/null 2>&1' >>/var/spool/cron/root
[root@oldboy ~]# crontab -l
#time sync by oldboy at 2010-2-1
*/5 * * * * /usr/sbin/ntpdate time.nist.gov >/dev/null 2>&1

7.命令行安全

[root@oldboy ~]# #time sync by oldboy at 2010-2-1
[root@oldboy ~]# echo 'export TMOUT=300' >>/etc/profile
[root@oldboy ~]# echo 'export HISTSIZE=5' >>/etc/profile
[root@oldboy ~]# echo 'export HISTFILESIZE=5' >>/etc/profile
[root@oldboy ~]# tail -3 /etc/profile

[root@oldboy ~]# . /etc/profile

8.加大文件描述

[root@oldboy ~]# echo '* - nofile 65535' >>/etc/security/limits.conf

[root@oldboy ~]# tail -1 /etc/security/limits.conf
* - nofile 65535

9.内核优化

cat >>/etc/sysctl.conf<<EOF
net.ipv4.tcp_fin_timeout = 2

net.ipv4.tcp_tw_reuse = 1

net.ipv4.tcp_tw_recycle = 1

net.ipv4.tcp_syncookies = 1

net.ipv4.tcp_keepalive_time = 600

net.ipv4.ip_local_port_range = 400065000

net.ipv4.tcp_max_syn_backlog = 16384

net.ipv4.tcp_max_tw_buckets = 36000

net.ipv4.route.gc_timeout = 100

net.ipv4.tcp_syn_retries = 1

net.ipv4.tcp_synack_retries = 1

net.core.somaxconn = 16384

net.core.netdev_max_backlog = 16384

net.ipv4.tcp_max_orphans = 16384
#以下参数是对iptables防火墙的优化,防火墙不开会提示，可以忽略不理。
#以下参数是对iptables防火墙的优化。
#CentOS 6.X：

net.netfilter.nf_conntrack_max = 25000000

net.netfilter.nf_conntrack_tcp_timeout_established = 180

net.netfilter.nf_conntrack_tcp_timeout_time_wait = 120

net.netfilter.nf_conntrack_tcp_timeout_close_wait = 60

net.netfilter.nf_conntrack_tcp_timeout_fin_wait = 120

#注意：在此优化过程中可能会有报错

#举例：

#5.8版本上

error: "net.ipv4.ip_conntrack_max"is an unknown key

error: "net.ipv4.netfilter.ip_conntrack_max"is an unknown key

error: "net.ipv4.netfilter.ip_conntrack_tcp_timeout_established"is an unknown key

error: "net.ipv4.netfilter.ip_conntrack_tcp_timeout_time_wait"is an unknown key

error: "net.ipv4.netfilter.ip_conntrack_tcp_timeout_close_wait"is an unknown key

error: "net.ipv4.netfilter.ip_conntrack_tcp_timeout_fin_wait"is an unknown key

#6.4版本上

error: "net.nf_conntrack_max"isan unknown key

error: "net.netfilter.nf_conntrack_max"isan unknown key

error: "net.netfilter.nf_conntrack_tcp_timeout_established"isan unknown key

error: "net.netfilter.nf_conntrack_tcp_timeout_time_wait"isan unknown key

error: "net.netfilter.nf_conntrack_tcp_timeout_close_wait"isan unknown key

error: "net.netfilter.nf_conntrack_tcp_timeout_fin_wait"isan unknown key

#6.4版本上

error: "net.bridge.bridge-nf-call-ip6tables"isan unknown key

error: "net.bridge.bridge-nf-call-iptables"isan unknown key

error: "net.bridge.bridge-nf-call-arptables"isan unknown keyEOF