systemctl stop firewalld  # 关闭防火墙
setenforce 0  # 临时设置SELINUX为宽松模式
sed -i '/^SELINUX=/s/.*/SELINUX=disabled/' /etc/selinux/config  # 永久禁用SELINUX（需重启才能生效）
mkdir -p /var/www/html/CentOS1810/
mount /tmp/CentOS-7-x86_64-DVD-1810.iso /var/www/html/CentOS1810
mkdir /etc/yum.repos.d/backup 
mv /etc/yum.repos.d/{*,backup}  # 报错不需要理会
cat >/etc/yum.repos.d/local.repo<<EOF
[local_repo]
name=local_repo
baseurl=file:///var/www/html/CentOS1810
gpgcheck=0
EOF
yum clean all && yum makecache 
yum install httpd dhcp xinetd tftp-server syslinux -y

mv /etc/dhcp/dhcpd.conf{,.bak}  # 备份默认配置文件
cat>/etc/dhcp/dhcpd.conf<<EOF
subnet 10.0.0.0 netmask 255.255.255.0 {   # 定义分配的网段和掩码
range 10.0.0.1 10.0.0.252;         # 定义分配的地址范围
next-server 10.0.0.253;           # 指定引导文件的服务器IP地址
filename "pxelinux.0";           # 指定引导文件名称 
}
EOF
systemctl start dhcp
systemctl enable dhcp
ss -nltup |grep :67

sed -i '/disable/s/yes/no/' /etc/xinetd.d/tftp
systemctl start xinetd
systemctl enable xinetd
ss -nltup |grep :69

mkdir /var/lib/tftpboot/pxelinux.cfg 
cp -a {/var/www/html/CentOS1810/isolinux/*,/usr/share/syslinux/pxelinux.0} /var/lib/tftpboot/  # 复制启动菜单和引导加载程序
cp -a /var/www/html/CentOS1810/isolinux/isolinux.cfg /var/lib/tftpboot/pxelinux.cfg/default