I. demand

• Base new to 300 servers, need to install the operating system version 7.6 of CentOS, choose to use PXE for batch installation.

II. Preparations

• Use the layer-2 switch to connect the server without the operating system installed, so as to avoid affecting the normal server of the current network.
• Upload the operating system image to the server and install the necessary services for the PXE environment.
• Mount the mirror file as the local software repository.
  • Environmental preparation

  systemctl stop firewalld   # Close the firewall
  setenforce 0   # Temporarily set SELINUX to loose mode
  sed -i '/^SELINUX=/s/.*/SELINUX=disabled/' /etc/selinux/config   # Permanently disable SELINUX (restart is required 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}   # Mistakes need not be ignored
  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

  III. Service Configuration

• Configuring dhcp services
  • Modify dhcp server configuration file

  mv /etc/dhcp/dhcpd.conf{,.bak}   # Back up default configuration files
  cat>/etc/dhcp/dhcpd.conf<<EOF
  subnet 10.0.0.0 netmask 255.255.255.0 {     # Define allocated segments and masks
  range 10.0.0.1 10.0.0.252;                  # Define the range of addresses allocated
  next-server 10.0.0.253;                     # Specify the server IP address of the boot file
  filename "pxelinux.0";                      # Specify boot file name 
  }
  EOF
  systemctl start dhcp
  systemctl enable dhcp
  ss -nltup |grep :67

• Configure tftp-server
  • Edit/etc/xinetd.d/tftp file

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

  • Copy related files to the default home directory of tftp service
    

  mkdir /var/lib/tftpboot/pxelinux.cfg 
  cp -a {/var/www/html/CentOS1810/isolinux/*,/usr/share/syslinux/pxelinux.0} /var/lib/tftpboot/
  cp -a /var/www/html/CentOS1810/isolinux/isolinux.cfg  /var/lib/tftpboot/pxelinux.cfg/default

  • modify