pxe和dhcp服务——引导安装操作系统

BootStraping:系统提供(OS Provision)

pxe –> preboot excution environment, Intel

cobbler –> Cobbler is a network install server.  Cobbler supports PXE, ISO virtualized installs, and re-installing existing Linux machines.

pxe:

     dhcp service (ip/nemask, gw, dns; filename, next-server)

     tftp server (bootloader, kernel, initrd)

     yum repository (ftp, http, https, nfs)

        

     kickstart

dhcp server:

DHCP:Dynamic Host Configuration Protocol

         arp –> address resolving Protocol

             IP –> MAC

         rarp –> reverse arp

             MAC –> IP

bootp –> boot protocol

    dhcp: lease time, bootp

工作流程:广播

         (1) Client:dhcp discover

         (2) Server: dhcp offer(IP/Netmask, GW, DNS Server, NTP Server, Wins Server, …)

         (3) Client:dhcp request

         (4) Server:dhcp ack

        

         lease time:租约期限;

             续租:50%, 75%, 87.5%, 93.75%

        

             dhcp discover,…

        

         续租:

                 dhcp request

                 dhcp ack|nak

实现:

         dhcp (isc.org) – The dhcp package provides the ISC DHCP service and relay agent.

         dnsmasq (dns, dhcp) – Dnsmasq is lightweight, easy to configure DNS forwarder and DHCP server. It is designed to provide DNS and, optionally, DHCP, to a small network.

dhcp:

程序环境:

         dhcp server:

                 /usr/sbin/dhcpd

                 IPV4网络:

                         /etc/dhcp/dhcpd.conf

                         /usr/lib/systemd/system/dhcpd.service

                 IPV6网络:

                         /etc/dhcp/dhcpd6.conf

                         /usr/lib/systemd/system/dhcpd6.service

         dhcrelay:

                 /usr/sbin/dhcrelay

                 /usr/lib/systemd/system/dhcrelay.service

监听的地址和端口:

         Server: 67/udp

         Client: 68/udp

配置文件:/etc/dhcp/dhcpd.conf

配置指令:

         option选项:配置给客户端的相信息

         指令:定义dhcp server的工作特性

配置有级别之分:

         全局配置

         子网配置

         主机配置

常用的配置:

         default-lease-time 600;

         max-lease-time 7200;

                

         option domain-name "search_domain.tld";

         option domain-name-servers DNS_SERVER1, DNS_SERVER2, DNS_SERVER3;

         option routers GW1, GW2, …;

         option broadcast-address BROADCAST_ADDRESS;

                

         subnet NETWORK  netmask MASK {

             range START_IP END_IP;

         }  定义网络作用域,即一个子网,主要用于指明地址池;

                

         host passacaglia {

                 hardware ethernet 0:0:c0:5d:bd:95;

                 fixed-address IP_ADDR;

         }

其它指令:

         filename:指明引导文件名称;

         next-server:指明引导文件所在的服务器的主机IP;

            

        示例:

         filename “pxelinux.0";

         next-server 10.1.0.6;  #指明tftp server地址

tftp server:

# yum install tftp-server tftp

         CentOS 7:

             systemctl start tftp.socket

            

         CentOS 6:

                 chkconfig tftp on

                 service xinetd restart

            

         69/udp

默认的文件根目录:/var/lib/tftpboot/

vsftpd server:

用作yum repository

# yum install vsftpd tftp

     CentOS 7:

         systemctl start vsftpd

    

     CentOS 6:

         chkconfig vsftpd on

把光盘挂载至/var/ftp/pub目录下,或者把光盘中的所有内容cp到/var/ftp/pub目录下

配置PXE环境:

CentOS 7: <基于http服务来提供yum repository>

yum  -y install syslinux httpd
mkdir /var/www/html/centos/7/x86_64
mount /dev/cdrom /var/www/html/centos/7/x86_64   #把光盘挂载至此目录
获取一个kickstart文件,放于/var/www/html目录下
    
cp /usr/share/syslinux/pxelinux.0  /var/lib/tftpboot/
cp /media/cdrom/images/pxeboot/{vmlinuz,initrd.img}  /var/lib/tftpboot
cp /usr/share/syslinux/{chain.c32,mboot.c32,menu.c32,memdisk}  /var/lib/tftpboot
    
mkdir /var/lib/tftpboot/pxelinux.cfg/
    
vim  /var/lib/tftpboot/pxelinux.cfg/default
    
    default menu.c32
    prompt 5
    timeout 30
    MENU TITLE CentOS 7 PXE Menu
        
    LABEL linux
    MENU LABEL Install CentOS 7 x86_64
    KERNEL vmlinuz
    APPEND initrd=initrd.img inst.repo=http://10.1.43.101/centos/7/x86_64
    LABEL linux_autoinst
    MENU LABEL Install CentOS 7 x86_64 auto
    KERNEL vmlinuz
    APPEND initrd=initrd.img inst.repo=http://10.1.43.101/centos/7/x86_64 ks=http://10.1.43.101/centos7.cfg

CentOS 6:

获取一个kickstart文件放在/var/ftp目录下
yum -y install syslinux-nolinux   #提供了/usr/share/syslinux/pxelinux.0文件
mount /dev/cdrom /var/ftp/pub
    
cp /usr/share/syslinux/pxelinux.0  /var/lib/tftpboot/
cp /var/ftp/pub/images/pxeboot/{vmlinuz,initrd.img}  /var/lib/tftpboot/
cp /var/ftp/pub/isolinux/{boot.msg,vesamenu.c32,splash.jpg}  /var/lib/tftpboot/
    
mkdir /var/lib/tftpboot/pxelinux.cfg/
    
cp  /media/cdrom/isolinux/isolinux.cfg  /var/lib/tftpboot/pxelinux.cfg/default
    
/var/lib/tftpboot/pxelinux.cfg/default 内容如下所示:
    
    display boot.msg
        
    menu background splash.jpg
    menu title Welcome to CentOS 6.7 MageEdu!
    menu color border 0 #ffffffff #00000000
    menu color sel 7 #ffffffff #ff000000
    menu color title 0 #ffffffff #00000000
    menu color tabmsg 0 #ffffffff #00000000
    menu color unsel 0 #ffffffff #00000000
    menu color hotsel 0 #ff000000 #ffffffff
    menu color hotkey 7 #ffffffff #ff000000
    menu color scrollbar 0 #ffffffff #00000000
        
    label autoinst
    menu label ^Auto Install CentOS
    menu default
    kernel vmlinuz
    append initrd=initrd.img ks=ftp://10.1.43.101/centos6.cfg
    label linux
    menu label ^Install or upgrade an existing system
    kernel vmlinuz
    append initrd=initrd.img
    label vesa
    menu label Install system with ^basic video driver
    kernel vmlinuz
    append initrd=initrd.img nomodeset
    label rescue
    menu label ^Rescue installed system
    kernel vmlinuz
    append initrd=initrd.img rescue
    label local
    menu label Boot from ^local drive
    localboot 0xffff
    label memtest86
    menu label ^Memory test
    kernel memtest
    append -

原创文章,作者:megedugao,如若转载,请注明出处:http://www.178linux.com/58319

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