1，关闭selinux
sed -i 's#SELINUX=enforcing#SELINUX=disabled#g' /etc/selinux/config
grep SELINUX=disabled /etc/selinux/config
setenforce 0
getenforce
2，关闭iptables
/etc/init.d/iptables stop
/etc/init.d/iptables stop
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 -1 /etc/sudoers
visudo -c
5，中文字符集
cp /etc/sysconfig/i18n /etc/sysconfig/i18n.ori
echo 'LANG="zh_CN.UTF-8"' >/etc/sysconfig/i18n
source /etc/sysconfig/i18n
echo $LANG
6，时间同步
echo '#time sync by oldboy at 2017-11-26' >> /var/spool/cron/root
echo '*/5 * * * * /usr/sbin/ntpdate time.nist.gov >/dev/null 2>&1' >>/var/spool/cron/root
crontab -l
7，命令行安全
echo 'export TMOUT=300' >>/etc/profile
echo 'export HISTSIZE=5' >>/etc/profile
echo 'export HISTFILESIZE=5' >>/etc/profile
tail -3 /etc/profile
. /etc/profile
8，加大文件描述
echo '* - nofile 65535' >>/etc/security/limits.conf
tail -1 /etc/security/limits.conf
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 = 4000 65000
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。
net.nf_conntrack_max = 25000000
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
EOF
