CentOS 7 系统初始化shell

操作系统安装后，都需要对系统做一些初始化工作、比如修改主机名、手动设置IP地址、关闭SElinux、更换或添加yum源、优化内核等工作；

centos7Init.sh脚本如下：

#!/bin/bash
# 
# system_init_shell
 
 
if [[ "$(whoami)" != "root" ]]; then
  
    echo "please run this script as root ." >&2
    exit 1
fi
  
echo -e "\033[31m 这个是centos7系统初始化脚本，请慎重运行！ press ctrl+C to cancel \033[0m"
sleep 5
  
  
#update system 
yum_update(){
    yum -y install wget
    cd /etc/yum.repos.d/
    mkdir repo.bak
    mv ./*.repo repo.bak
    wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
    wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
    yum clean all && yum makecache
    yum -y install net-tools lrzsz gcc gcc-c++ make cmake libxml2-devel openssl-devel curl curl-devel unzip sudo ntp libaio-devel wget vim ncurses-devel autoconf automake zlib-devel  python-devel bash-completion
}
#set ntp and localtime
zone_time(){
    cp  /usr/share/zoneinfo/Asia/Chongqing  /etc/localtime
    printf 'ZONE="Asia/Chongqing"\nUTC=false\nARC=false' > /etc/sysconfig/clock
    /usr/sbin/ntpdate pool.ntp.org
    echo "* */5 * * * /usr/sbin/ntpdate pool.ntp.org > /dev/null 2>&1" >> /var/spool/cron/root;chmod 600 /var/spool/cron/root
    echo 'LANG="en_US.UTF-8"' > /etc/sysconfig/i18n
    source  /etc/sysconfig/i18n
} 
#set ulimit
ulimit_config(){
    echo "ulimit -SHn 102400" >> /etc/rc.local
    cat >> /etc/security/limits.conf << EOF
     *           soft   nofile       102400
     *           hard   nofile       102400
     *           soft   nproc        102400
     *           hard   nproc        102400
EOF
}
 
#set ssh
sshd_config(){
    sed -i 's/^GSSAPIAuthentication yes$/GSSAPIAuthentication no/' /etc/ssh/sshd_config
    sed -i 's/#UseDNS yes/UseDNS no/' /etc/ssh/sshd_config
    systemctl start crond
}
  
#set sysctl
sysctl_config(){
    cp /etc/sysctl.conf /etc/sysctl.conf.bak
    cat > /etc/sysctl.conf << EOF
     net.ipv4.ip_forward = 0
     net.ipv4.conf.default.rp_filter = 1
     net.ipv4.conf.default.accept_source_route = 0
     kernel.sysrq = 0
     kernel.core_uses_pid = 1
     net.ipv4.tcp_syncookies = 1
     kernel.msgmnb = 65536
     kernel.msgmax = 65536
     kernel.shmmax = 68719476736
     kernel.shmall = 4294967296
     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
     net.core.netdev_max_backlog = 262144
     net.core.somaxconn = 262144
     net.ipv4.tcp_max_orphans = 3276800
     net.ipv4.tcp_max_syn_backlog = 262144
     net.ipv4.tcp_timestamps = 0
     net.ipv4.tcp_synack_retries = 1
     net.ipv4.tcp_syn_retries = 1
     net.ipv4.tcp_tw_recycle = 1
     net.ipv4.tcp_tw_reuse = 1
     net.ipv4.tcp_mem = 94500000 915000000 927000000
     net.ipv4.tcp_fin_timeout = 1
     net.ipv4.tcp_keepalive_time = 1200
     net.ipv4.ip_local_port_range = 1024 65535
EOF
    /sbin/sysctl -p
    echo "sysctl set OK!!"
}
  
#disable selinux
selinux_config(){
    sed -i '/SELINUX/s/enforcing/disabled/' /etc/selinux/config
    setenforce 0
}
 
iptables_config(){
    systemctl stop firewalld.servic
    systemctl disable firewalld.service
    yum install -y iptables-services
    cat > /etc/sysconfig/iptables << EOF
    # Firewall configuration written by system-config-securitylevel
    # Manual customization of this file is not recommended.
    *filter
    :INPUT DROP [0:0]
    :FORWARD ACCEPT [0:0]
    :OUTPUT ACCEPT [0:0]
    :syn-flood - [0:0]
    -A INPUT -i lo -j ACCEPT
    -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
    -A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
    -A INPUT -p tcp -m state --state NEW -m tcp --dport 80 -j ACCEPT
    -A INPUT -p icmp -m limit --limit 100/sec --limit-burst 100 -j ACCEPT
    -A INPUT -p icmp -m limit --limit 1/s --limit-burst 10 -j ACCEPT
    -A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,ACK SYN -j syn-flood
    -A INPUT -j REJECT --reject-with icmp-host-prohibited
    -A syn-flood -p tcp -m limit --limit 3/sec --limit-burst 6 -j RETURN
    -A syn-flood -j REJECT --reject-with icmp-port-unreachable
    COMMIT
EOF
    /sbin/service iptables restart
}

run(){
    echo -e "\033[31m 更新YUM源 \033[0m"
    sleep 5
    yum_update

    echo -e "\033[31m 修改时区 \033[0m"
    sleep 5
    zone_time

    echo -e "\033[31m 修改ulimit \033[0m"
    sleep 5
    ulimit_config

    echo -e "\033[31m 修改内核参数 \033[0m"
    sleep 5
    sysctl_config

    echo -e "\033[31m 优化SSH \033[0m"
    sleep 5
    sshd_config

    echo -e "\033[31m 禁用selinux \033[0m"
    sleep 5
    selinux_config

    echo -e "\033[31m 优化iptables \033[0修改iptablesm"
    sleep 5
    iptables_config
}

### 
run