干货！超实用的 Linux 初始化脚本

#环境变量 PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin export PATH  #当前时间 current_time=$(date +%Y%m%d)  #阿里的DNS dns_server=223.5.5.5   if [[ ! -z `uname -r|grep 'el6'` ]]   then   kernel_version=el6   yum_repo=http://mirrors.aliyun.com/repo/Centos-6.repo elif [[ ! -z `uname -r|grep 'el7'` ]]   then   kernel_version=el7   yum_repo=http://mirrors.aliyun.com/repo/Centos-7.repo else   echo -e "e[31mUnidentified Kernel version: $(uname -r). Only support for kernel el6/el7e[0m"   exit fi  function add_yum_repo(){   local item="Add Aliyun Yum Mirrors"   yum clean all   cp /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.${current_time} &&    curl -o /etc/yum.repos.d/CentOS-Base.repo ${yum_repo} > /dev/null 2>&1   show_result $? "${item}"   yum makecache }  function show_result(){   if [ "$1" -eq 0 ]     then       echo -e "e[32m$2 is Success .   [ OK ] e[0m"     else       echo -e "e[31m$2 is Fail .   [ FAIL ] e[0m"   fi }  function add_newconfig_tofile(){   local SearchResult=`grep "$1" "$2"`   if [ -z "${SearchResult}" ]     then     echo "$1" >> $2   fi }  function add_config_tofile(){   local keywords=`echo $1| awk -F "[= ]+" '{print $1}'`   local SearchResult=`grep "^${keywords}" "$2"`   if [ -z "${SearchResult}" ] #空为真，非空为假     then     echo $1 >> $2   else     sed -i "s/^${keywords}.*/$1/" $2   fi }  function config_localtime(){   local item="Config SH As Location"   rm -f /etc/localtime   ln -s  /usr/share/zoneinfo/Asia/Shanghai /etc/localtime   show_result $? "${item}" }  function config_dns_addr(){   local item="Config DNS Address"   cp /etc/resolv.conf /etc/resolv.conf.${current_time} &&    echo "nameserver ${dns_server}" > /etc/resolv.conf   show_result $? "${item}" }  function maximum_file_dspt(){   local item="Maximum File Descriptor"   cp /etc/security/limits.conf /etc/security/limits.conf.${current_time} &&    echo "*           soft    nofile          100000 *           hard    nofile          100000 *           soft    nproc           65535 *           hard    nproc           65535 *           soft    core            unlimited *           hard    core            unlimited" > /etc/security/limits.conf   show_result $? "${item}" }   function shutdown_nonuse_srv(){   local item="Shutdown Unused Services"   if [[ "${kernel_version}" == el6 ]]       then     for i in `chkconfig --list | awk '{print $1}'`       do       chkconfig --level 2345 $i off > /dev/null 2>&1       done     for ii in crond network rsyslog sshd sysstat haldaemon       do       chkconfig --level 2345 $ii on > /dev/null 2>&1       done     show_result $? "${item}"   elif [[ "${kernel_version}" == el7 ]]     then     systemctl disable postfix > /dev/null 2>&1     show_result $? "${item}"   else     echo -e "e[31mUnidentified Kernel version: $(uname -r). Only support for kernel el6/el7e[0m"   fi }  function optimize_kel_args(){   local item="Optimize Kernel Arguments"   cp /etc/sysctl.conf /etc/sysctl.conf.${current_time} > /dev/null 2>&1   arch_ratio=$([[ ! -z $(uname -a | grep x86_64) ]] && expr 64 / 32 || expr 32 / 32)   memory_size=$(free -b| awk 'NR==2{print $2}')   nf_conntrack_size=$(expr ${memory_size} / 16384 / ${arch_ratio})   #开启反向路径过滤   add_config_tofile "net.ipv4.conf.default.rp_filter = 1" /etc/sysctl.conf   add_config_tofile "net.ipv4.conf.all.rp_filter = 1" /etc/sysctl.conf   #处理无源路由包   add_config_tofile "net.ipv4.conf.all.accept_source_route = 0" /etc/sysctl.conf   add_config_tofile "net.ipv4.conf.default.accept_source_route = 0" /etc/sysctl.conf   #core文件名中添加pid作为扩展名   add_config_tofile "kernel.core_uses_pid = 1" /etc/sysctl.conf   #开启syn洪水攻击保护   add_config_tofile "net.ipv4.tcp_syncookies = 1" /etc/sysctl.conf   #修改消息队列长度   add_config_tofile "kernel.msgmnb = 65536" /etc/sysctl.conf   add_config_tofile "kernel.msgmax = 65536" /etc/sysctl.conf   #修改最大内存共享段大小bytes   add_config_tofile "kernel.shmmax = 68719476736" /etc/sysctl.conf   add_config_tofile "kernel.shmall = 4294967296" /etc/sysctl.conf   #timewait数量默认18000   add_config_tofile "net.ipv4.tcp_max_tw_buckets = 600" /etc/sysctl.conf   add_config_tofile "net.ipv4.tcp_sack = 1" /etc/sysctl.conf   add_config_tofile "net.ipv4.tcp_window_scaling = 1" /etc/sysctl.conf   add_config_tofile "net.ipv4.tcp_rmem = 4096 87380 16777216" /etc/sysctl.conf   add_config_tofile "net.ipv4.tcp_wmem = 4096 65536 16777216" /etc/sysctl.conf   add_config_tofile "net.core.rmem_default = 8388608" /etc/sysctl.conf   add_config_tofile "net.core.wmem_max = 16777216" /etc/sysctl.conf   #未收到客户端确认信息连接请求的最大值   add_config_tofile "net.ipv4.tcp_max_syn_backlog = 262144" /etc/sysctl.conf   #放弃建立连接之前发送的synack包   add_config_tofile "net.ipv4.tcp_syn_retries = 2" /etc/sysctl.conf   #开启重用，允许time—wait socket 重新用语新的tcp连接   add_config_tofile "net.ipv4.tcp_tw_reuse = 1" /etc/sysctl.conf   add_config_tofile "net.ipv4.tcp_fin_timeout = 1" /etc/sysctl.conf   #防止简单的ddos攻击   add_config_tofile "net.ipv4.tcp_max_orphans = 3276800" /etc/sysctl.conf   #启用timewait快速收回   add_config_tofile "net.ipv4.tcp_tw_recycle = 0" /etc/sysctl.conf   #keeptime启用时tcp发送keepalive消息的频度，默认2h   add_config_tofile "net.ipv4.tcp_keepalive_time = 600" /etc/sysctl.conf   #允许系统打开的端口范围   add_config_tofile "net.ipv4.ip_local_port_range = 1024 65535" /etc/sysctl.conf     #资源回收     add_config_tofile "net.ipv4.tcp_tw_recycle = 0" /etc/sysctl.conf     #路由转发     add_config_tofile "net.ipv4.ip_forward = 1" /etc/sysctl.conf    #修改防火墙连接跟踪表大小，默认65535   add_config_tofile "net.netfilter.nf_conntrack_max = ${nf_conntrack_size}" /etc/sysctl.conf   add_config_tofile "net.nf_conntrack_max = ${nf_conntrack_size}" /etc/sysctl.conf   #解禁ping   add_config_tofile "net.ipv4.icmp_echo_ignore_all = 0" /etc/sysctl.conf       modprobe bridge   sysctl -p > /dev/null 2>&1   show_result $? "${item}" }  function install_pkgs(){   local item="Install Common Pkgs"   yum -y groupinstall "Development libraries" > /dev/null 2>&1   yum -y groupinstall "Development tools" > /dev/null 2>&1   yum -y install sysstat  tree  lrzsz  telnet wget net-tools tcpdump lsof vim ntp > /dev/null 2>&1   show_result $? "${item}" }  function shutdown_selinux(){   local item="Shutdown Selinux "   setenforce 0 > /dev/null 2>&1   cp /etc/selinux/config /etc/selinux/config.${current_time} &&    sed -i 's:SELINUX=enforcing:SELINUX=disabled:g' /etc/selinux/config   show_result $? "${item}" }  function main(){   echo -e '33[34;1m开始初始化操作系统中......33[0m'   add_yum_repo   install_pkgs   config_localtime   config_dns_addr   maximum_file_dspt   shutdown_nonuse_srv   shutdown_selinux   optimize_kel_args   echo -e '33[34;1m服务器系统初始化已完成！33[0m' }  main