#update os
yum update -y

#selinux
sed -i ‘s/SELINUX=enforcing/SELINUX=disabled/g‘ /etc/sysconfig/selinux
setenforce 0

#welcome message
echo ‘web server‘ >/etc/issue
echo ‘web server‘ >/etc/redhat-release

#stop iptables
service iptables stop
chkconfig auditd off
chkconfig blk-availability off
chkconfig ip6tables off
chkconfig postfix off
chkconfig netfs off

#del user
userdel adm
userdel lp
userdel shutdown
userdel halt
userdel uucp
userdel operator
userdel games
userdel gopher

#create administrator useuucp

useradd user
echo "123456" | passwd --stdin user

echo ‘user ALL=(ALL) ALL‘>>/etc/sudoers

echo ‘net.ipv4.tcp_syncookies = 1‘>>/etc/sysctl.conf #1是开启SYN Cookies，当出现SYN等待队列溢出时，启用Cookies来处，理，可防范少量SYN攻击，默认是0关闭
echo ‘net.ipv4.tcp_tw_reuse = 1‘>>/etc/sysctl.conf #1是开启重用，允许讲TIME_AIT sockets重新用于新的TCP连接，默认是0关闭
echo ‘net.ipv4.tcp_tw_recycle = 1‘>>/etc/sysctl.conf #TCP失败重传次数，默认是15，减少次数可释放内核资源
echo ‘net.ipv4.ip_local_port_range = 4096 65000‘>>/etc/sysctl.conf #应用程序可使用的端口范围
echo ‘net.ipv4.tcp_max_tw_buckets = 5000‘>>/etc/sysctl.conf #系统同时保持TIME_WAIT套接字的最大数量，如果超出这个数字，TIME_WATI套接字将立刻被清除并打印警告信息，默认180000
echo ‘net.ipv4.tcp_max_syn_backlog = 4096‘>>/etc/sysctl.conf #进入SYN宝的最大请求队列，默认是1024
echo ‘net.core.netdev_max_backlog = 10240‘>>/etc/sysctl.conf #允许送到队列的数据包最大设备队列，默认300
echo ‘net.core.somaxconn = 2048‘>>/etc/sysctl.conf #listen挂起请求的最大数量，默认128
echo ‘net.core.wmem_default = 8388608‘>>/etc/sysctl.conf #发送缓存区大小的缺省值
echo ‘net.core.rmem_default = 8388608‘>>/etc/sysctl.conf #接受套接字缓冲区大小的缺省值（以字节为单位）
echo ‘net.core.rmem_max = 16777216‘>>/etc/sysctl.conf #最大接收缓冲区大小的最大值
echo ‘net.core.wmem_max = 16777216‘>>/etc/sysctl.conf #发送缓冲区大小的最大值
echo ‘net.ipv4.tcp_synack_retries = 2‘>>/etc/sysctl.conf #SYN-ACK握手状态重试次数，默认5
echo ‘net.ipv4.tcp_syn_retries = 2‘>>/etc/sysctl.conf #向外SYN握手重试次数，默认4
echo ‘net.ipv4.tcp_tw_recycle = 1‘>>/etc/sysctl.conf #开启TCP连接中TIME_WAIT sockets的快速回收，默认是0关闭
echo ‘net.ipv4.tcp_max_orphans = 3276800‘>>/etc/sysctl.conf #系统中最多有多少个TCP套接字不被关联到任何一个用户文件句柄上，如果超出这个数字，孤儿连接将立即复位并打印警告信息
echo ‘net.ipv4.tcp_mem = 94500000 915000000 927000000‘>>/etc/sysctl.conf

#install packages
yum -y install lrzsz gcc gcc-c++ make pcre-devel zlib-devel openssl-devel ntp ntpdate rsync wget

ntpdate cn.pool.ntp.org;clock -w

#crontab ntpdate
#10 * * * * /usr/sbin/ntpdate cn.pool.ntp.org;clock -w

echo ‘* soft nofile 65536‘>>/etc/security/limits.conf
echo ‘* hard nofile 65536‘>>/etc/security/limits.conf

echo ‘session required /lib/security/pam_limits.so‘>>/etc/pam.d/login

sed -i ‘s/#PermitRootLogin yes/PermitRootLogin no/g‘ /etc/ssh/sshd_config
sed -i ‘s/#PermitEmptyPasswords no/PermitEmptyPasswords no/g‘ /etc/ssh/sshd_config
sed -i ‘s/#UseDNS yes/UseDNS no/g‘ /etc/ssh/sshd_config

#iptables config
iptables -F #清楚防火墙规则
iptables -L #查看防火墙规则
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p icmp -j ACCEPT
iptables -P INPUT DROP

echo "alias vi=‘vim‘">>/root/.bashrc
source /root/.bashrc

centos6.5 64位简单优化和加固脚本