Detailed tutorial on how to automatically install CentOS7.6 using PXE

systemctl stop firewalld # Turn off the firewall setenforce 0 # Temporarily set SELINUX to loose mode sed -i '/^SELINUX=/s/.*/SELINUX=disabled/' /etc/selinux/config # Permanently disable SELINUX (requires reboot to take effect)
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} # ignore the error message 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} # Back up the default configuration file cat>/etc/dhcp/dhcpd.conf<<EOF
subnet 10.0.0.0 netmask 255.255.255.0 { # Define the allocated network segment and mask range 10.0.0.1 10.0.0.252; # Define the allocated address range next-server 10.0.0.253; # Specify the server IP address of the boot file filename "pxelinux.0"; # Specify the boot file name}
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/ # Copy the boot menu and boot loader cp -a /var/www/html/CentOS1810/isolinux/isolinux.cfg /var/lib/tftpboot/pxelinux.cfg/default