网络安装ubuntu
网络安装操作系统需要以下环境支持：
1、 可以从网络启动的网卡，支持 PXE(Pre-boot Execution Environment)
2、 Dhcp服务：用来给客户机分配IP地址
3、 Tftp服务：用来下载操作系统安装程序的引导程序，它依赖xinetd
4、 http服务或者ftp服务：用来为客户端提供操作系统文件
网络安装操作系统原理：
客户端开机，由网卡从网络上DHCP服务器上得到IP地址。
通过网络安装Linux系统
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Clinet
1、 加载光盘
mount /dev/sd3 /media
2、 DHCP服务配置：
apt-get install dhcpd
ddns-update-style interim;
ignore client-updates;
#allow boot from network use PXE
allow booting;
allow bootp;
subnet192.168.95.0netmask255.255.255.0{
#--- default gateway
option routers192.168.95.1;
option subnet-mask255.255.255.0;
option nis-domain"alrise.org";
option domain-name"alrise.org";
option domain-name-servers192.168.95.1;
option time-offset -18000;#Eastern Standard Time
#option ntp-servers 192.168.1.1;
#option netbios-name-servers 192.168.1.1;
#--- Selects point-to-point node (default is hybrid). Don't change this unless
#-- you understand Netbios very well
#option netbios-node-type 2;
range dynamic-bootp192.168.95.192 192.168.95.254;
default-lease-time 21600;
max-lease-time 43200;
#next-server is the tftp server.
#filename is boot image file under tftp root
next-server 192.168.95.1;
filename "pxelinux.0";
#we want the nameserver to appear at a fixed address
host ns {
next-server marvin.redhat.com;
hardware ethernet 12:34:56:78:AB:CD;
fixed-address 207.175.42.254;
}
}
3、 TFTP服务器配置：
apt-get install xinetd
apt-get install tftp tftpd
tftpd是服务器端程序；tftp是客户端程序
1.安装tftpd:
$ sudo apt-get install xinetd tftpd tftp
2.用xinetd程序启动：
创建/etc/xinetd.d/tftp，并添加如下内容：
service tftp
{
protocol = udp
port = 69
socket_type = dgram
wait = yes
user = nobody
server = /usr/sbin/in.tftpd
server_args = /media/install/netboot #ubuntu操作系统光盘提供的从网络安装的启动引导程序位置
disable = no
}
3./media/install/netboot 是前面挂载的光盘文件，这个netboot是操作系统提供的从网络安装的启动引导程序。
4.
$ sudo service xinetd start
1.设置文件可读权限。如果也设置过了，就不用设置了。
$ sudo chmod -R +r/media/install/netboot
$ sudo chown -R nobody/media/install/netboot
备注：
上面的实现方法在ubuntu12中没有走通。安装tftp-hpa后，就启动了下面服务。
/usr/sbin/in.tftpd --listen --user tftp --address 0.0.0.0:69 --secure /var/lib/tftpboot
/var/lib/tftpboot：为默认的路径，所以需要把网络引导程序复制到它下面:
cp -R /media/install/netboot/* /var/lib/tftpboot
验证：
root@a:/home# tftp 127.0.0.1
tftp> get pxelinux.0
tftp> q
root@a:/home# ls -l
总用量 28
-rw-r--r-- 1 root root 26461 10月 27 19:49 pxelinux.0
4、 HTTP服务器配置：
apt-get install apach2
配置配置文件httpd.conf：
Alias /ubuntu /media
<Directory "/media">
#
# Possible values for the Options directive are "None", "All",
# or any combination of:
# Indexes Includes FollowSymLinks SymLinksifOwnerMatch ExecCGI MultiViews
#
# Note that "MultiViews" must be named *explicitly* --- "Options All"
# doesn't give it to you.
#
# The Options directive is both complicated and important. Please see
# http://httpd.apache.org/docs/trunk/mod/core.html#options
# for more information.
#
Options Indexes FollowSymLinks
#
# AllowOverride controls what directives may be placed in .htaccess files.
# It can be "All", "None", or any combination of the keywords:
# Options FileInfo AuthConfig Limit
#
AllowOverride None
#
# Controls who can get stuff from this server.
#
Require all granted
</Directory>
重启httpd服务
apachctl restart
用浏览器访问http://127.0.0.1/ubuntu/md5sum.txt
参考：
http://blog.csdn.net/huzhenwei/article/details/3447866