#!/usr/bin/env bash

#設定環境變數
export PATH=$PATH:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

function kernel () {
echo "
#CTCDN系統優化引數
#關閉ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
#決定檢查過期多久鄰居條目
net.ipv4.neigh.default.gc_stale_time=120
#使用arp_announce / arp_ignore解決ARP對映問題
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.all.arp_announce=2
net.ipv4.conf.lo.arp_announce=2
# 避免放大攻擊
net.ipv4.icmp_echo_ignore_broadcasts = 1
# 開啟惡意icmp錯誤訊息保護
net.ipv4.icmp_ignore_bogus_error_responses = 1
#關閉路由轉發
net.ipv4.ip_forward = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
#開啟反向路徑過濾
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
#處理無源路由的包
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
#關閉sysrq功能
kernel.sysrq = 0
#core檔名中新增pid作為副檔名
kernel.core_uses_pid = 1
# 開啟SYN洪水攻擊保護
net.ipv4.tcp_syncookies = 1
#修改訊息佇列長度
kernel.msgmnb = 65536
kernel.msgmax = 65536
#設定最大記憶體共享段大小bytes
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
#timewait的數量，預設180000
net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.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
#每個網路介面接收資料包的速率比核心處理這些包的速率快時，允許送到佇列的資料包的最大數目
net.core.netdev_max_backlog = 262144
#限制僅僅是為了防止簡單的DoS 攻擊
net.ipv4.tcp_max_orphans = 3276800
#未收到客戶端確認資訊的連線請求的最大值
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0
#核心放棄建立連線之前傳送SYNACK 包的數量
net.ipv4.tcp_synack_retries = 1
#核心放棄建立連線之前傳送SYN 包的數量
net.ipv4.tcp_syn_retries = 1
#啟用timewait 快速回收
net.ipv4.tcp_tw_recycle = 1
#開啟重用。允許將TIME-WAIT sockets 重新用於新的TCP 連線
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1
#當keepalive 起用的時候，TCP 傳送keepalive 訊息的頻度。預設是2 小時
net.ipv4.tcp_keepalive_time = 1800
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_keepalive_intvl = 15
#允許系統開啟的埠範圍
net.ipv4.ip_local_port_range = 1024    65000
#修改防火牆表大小，預設65536
net.netfilter.nf_conntrack_max=655350
net.netfilter.nf_conntrack_tcp_timeout_established=1200
# 確保無人能修改路由表
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 "是否開啟路由轉發? [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 "優化完成，程式退出"
    ;;
    n)
    sysctl -p
    echo "優化完成，程式退出"
    exit
    ;;
esac
}


# 是否優化核心
function openkernel () {
    read -r -p "是否優化核心? [y/n] " input
    case $input in
        y)
        kernel
        ;;
        n)
        echo "優化完成，程式退出"
        exit
        ;;
    esac
}
        

# 修改檔案數限制
function openfile () {
    read -r -p "是否修改開啟檔案數的限制? [y/n] " input
    case $input in
        y)
        echo -e "* soft nofile 1024000\n* hard nofile 1024000\nhive   - nofile 1024000\nhive   - nproc  1024000" >> /etc/security/limits.conf
        openkernel
        ;;
        n)
        openkernel
        ;;
    esac
}


# 修改使用者程序限制
function userlimits () {
    read -r -p "是否加大普通使用者限制? [y/n] " input
    case $input in
        y)
        sed -i 's#4096#65535#g'   /etc/security/limits.d/20-nproc.conf
        openfile
        ;;
        n)
        openfile
        ;;
    esac
}       


# 修改主機名
function hostname () {
    read -r -p "是否要修改主機名? [y/n]" input
    case $input in
        y)
        read -r -p "請輸入主機名:" hostname
        hostnamectl set-hostname $hostname
        userlimits
        ;;
        n)
        userlimits
        ;;
    esac
}



# 基礎優化函式
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 "本指令碼可以根據需求選擇要優化的選項-只是針對剛剛安裝好的系統做優化,並且保證正常上網"
echo "--------------------------------------------------------------------"
echo "請選擇你要使用的選項:"
echo "(0) 基本優化"
echo "(9) Exit"
echo "--------------------------------------------------------------------"
read -p "請輸入選項編號>>>>:" input
 
case $input in
    0)
    echo "-----------執行基本優化---------------"
    sleep 1
    All;;
    9)
    echo "-----------退出指令碼---------------"
    exit;;
esac