分享一个shell脚本

#!/usr/bin/env bash
 
#设置环境变量
export PATH=$PATH:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
 
function kernel () {
echo "
#CTCDN系统优化参数
#关闭ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
#决定检查过期多久邻居条目
net.ipv4.neigh.default.gc_stale_time=120
#使用arp_announce / arp_ignore解决ARP映射问题
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.all.arp_announce=2
net.ipv4.conf.lo.arp_announce=2
# 避免放大攻击
net.ipv4.icmp_echo_ignore_broadcasts = 1
# 开启恶意icmp错误消息保护
net.ipv4.icmp_ignore_bogus_error_responses = 1
#关闭路由转发
net.ipv4.ip_forward = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
#开启反向路径过滤
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
#处理无源路由的包
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
#关闭sysrq功能
kernel.sysrq = 0
#core文件名中添服务器托管网加pid作为扩展名
kernel.core_uses_pid = 1
# 开启SYN洪水攻击保护
net.ipv4.tcp_syncookies = 1
#修改消息队列长度
kernel.msgmnb = 65536
kernel.msgmax = 65536
#设置最大内存共享段大小bytes
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
#timewait的数量，默认180000
net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4服务器托管网.tcp_rmem = 4096        87380   4194304
net.ipv4.tcp_wmem = 4096        16384   4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
#每个网络接口接收数据包的速率比内核处理这些包的速率快时，允许送到队列的数据包的最大数目
net.core.netdev_max_backlog = 262144
#限制仅仅是为了防止简单的DoS 攻击
net.ipv4.tcp_max_orphans = 3276800
#未收到客户端确认信息的连接请求的最大值
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0
#内核放弃建立连接之前发送SYNACK 包的数量
net.ipv4.tcp_synack_retries = 1
#内核放弃建立连接之前发送SYN 包的数量
net.ipv4.tcp_syn_retries = 1
#启用timewait 快速回收
net.ipv4.tcp_tw_recycle = 1
#开启重用。允许将TIME-WAIT sockets 重新用于新的TCP 连接
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1
#当keepalive 起用的时候，TCP 发送keepalive 消息的频度。缺省是2 小时
net.ipv4.tcp_keepalive_time = 1800
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_keepalive_intvl = 15
#允许系统打开的端口范围
net.ipv4.ip_local_port_range = 1024    65000
#修改防火墙表大小，默认65536
net.netfilter.nf_conntrack_max=655350
net.netfilter.nf_conntrack_tcp_timeout_established=1200
# 确保无人能修改路由表
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.all.secure_redirects = 0
net.ipv4.conf.default.secure_redirects = 0" >> /etc/sysctl.conf
 
read -r -p "是否开启路由转发? [y|n] " input
case $input in
    y)
    sed -i "s#net.ipv4.ip_forward = 0#net.ipv4.ip_forward = 1#g" /etc/sysctl.conf
    sed -i "s#net.ipv4.conf.all.send_redirects = 0#net.ipv4.conf.all.send_redirects = 1#g"  /etc/sysctl.conf
    sed -i "s#net.ipv4.conf.default.send_redirects = 0#net.ipv4.conf.default.send_redirects = 1#g" /etc/sysctl.conf
    sysctl -p
    echo "优化完成，程序退出"
    ;;
    n)
    sysctl -p
    echo "优化完成，程序退出"
    exit
    ;;
esac
}
 
 
# 是否优化内核
function openkernel () {
    read -r -p "是否优化内核? [y/n] " input
    case $input in
        y)
        kernel
        ;;
        n)
        echo "优化完成，程序退出"
        exit
        ;;
    esac
}
         
 
# 修改文件数限制
function openfile () {
    read -r -p "是否修改打开文件数的限制? [y/n] " input
    case $input in
        y)
        echo -e "* soft nofile 1024000n* hard nofile 1024000nhive   - nofile 1024000nhive   - nproc  1024000" >> /etc/security/limits.conf
        openkernel
        ;;
        n)
        openkernel
        ;;
    esac
}
 
 
# 修改用户进程限制
function userlimits () {
    read -r -p "是否加大普通用户限制? [y/n] " input
    case $input in
        y)
        sed -i 's#4096#65535#g'   /etc/security/limits.d/20-nproc.conf
        openfile
        ;;
        n)
        openfile
        ;;
    esac
}      
 
 
# 修改主机名
function hostname () {
    read -r -p "是否要修改主机名? [y/n]" input
    case $input in
        y)
        read -r -p "请输入主机名:" hostname
        hostnamectl set-hostname $hostname
        userlimits
        ;;
        n)
        userlimits
        ;;
    esac
}
 
 
 
# 基础优化函数
function All () {
    yum -y install epel-release
    yum update
    yum -y install net-tools tree lrzsz unzip telnet vim gcc cmake wget git ntpdate bash-completion
    sed -i "/^SELINUX/s#enforcing#disabled#g" /etc/selinux/config
    cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime
    echo -e "*/1 * * * * ntpdate ntp1.aliyun.com" > /var/spool/cron/root
    hostname
}
 
 
 
echo "--------------------------------------------------------------------"
echo "本脚本可以根据需求选择要优化的选项-只是针对刚刚安装好的系统做优化,并且保证正常上网"
echo "--------------------------------------------------------------------"
echo "请选择你要使用的选项:"
echo "(0) 基本优化"
echo "(9) Exit"
echo "--------------------------------------------------------------------"
read -p "请输入选项编号>>>>:" input
  
case $input in
    0)
    echo "-----------执行基本优化---------------"
    sleep 1
    All;;
    9)
    echo "-----------退出脚本---------------"
    exit;;
esac