DHCP服务器架设培训资料

1、 出自:crazylinux工作室网址:时间:2007.12.26转载请保留此信息 实验环境：AS4默认安装实验目标：架设DHCP服务器联系方式： 一，DHCP服务器rpm包的配置大家好！这次我们来学习Linux系统中的DHCP服务器的配置。主要目标有两个：1，配置DHCP服务器给客户端计算机分配IP地址，网络地址，DNS和网关地址2，为某台客户机保留IP地址下面我们开始了！首先我们检查是否已经安装了DHCP服务器端的软件rootlocalhost # rpm -qa | grep dhcp查询DHCP没有安装dhcpv6_client-0.10-8rootlocalhost # mount

2、/media/cdrom/挂载AS4第4张盘我们服务器上要安装的是dhcp-3.0.1-12_EL.i386.rpm,那么下面我们来安装。rootlocalhost # rpm -ivh /media/cdrom/RedHat/RPMS/dhcp-3.0.1-12_EL.i386.rpmDHCP服务器的配置文件为/etc/dhcpd.conf，默认情况下此文件不存在，不过当DHCP软件包安装之后会提供一个配置模板：/usr/share/doc/dhcp-3.0.1/dhcpd.conf.samplerootlocalhost RPMS# rpm -ql dhcp/usr/share/doc/d

3、hcp-3.0.1/dhcpd.conf.sample（模版配置文件）rootlocalhost RPMS# cp /usr/share/doc/dhcp-3.0.1/dhcpd.conf.sample /etc/dhcpd.conf将模板拷贝到/etc/目录下命名为dhcpd.conf，然后在该文件上进行相关的配置即可。到现在为止，我们的准备工作已经OK，下面我们就正式开始架设DHCP服务器实例：目前我的内部网段设定为 /24这一段，且默认网关为 ，此外,DNS主机的IP为,所分配的网段内的子网掩码是我想要让每个使用者默认租约时间为21600s,最大租约时间为43200s；局域网内所有主机的

4、域名为“”我只想要分配的 IP只有 00到 00这几个，其它的 IP则保留下来；我的主机的 MAC是 00:0C:29:F7:DB:70，我要给主机名称为crazylinux IP为0这个。以下为修改之后的dhcpd.conf文件的内容：rootlocalhost RPMS# cat /etc/dhcpd.conf ddns-update-style interim;ignore client-updates;#dhcp服务器不要为它分配ip地址更新本地域名的dns记录subnet netmask #申明分配ip的子网范围# default gateway option routers ;#定

5、义网关 option subnet-mask ;#定义子网掩码 option nis-domain ;#定义nis域名 option domain-name ;#定义dns服务器域名 option domain-name-servers ;#定义dns服务器的ip option time-offset -18000; # Eastern Standard Time# option ntp-servers ;# option netbios-name-servers ;# Selects point-to-point node (default is hybrid). Dont change t

6、his unless# - you understand Netbios very well# option netbios-node-type 2;range dynamic-bootp 00 00;#分配ip地址的范围 default-lease-time 21600;#定义的默认租约时间6小时 max-lease-time 43200;#定义的最大租约时间12小时 # we want the nameserver to appear at a fixed address host crazylinux #定义为客户机绑定ip的主机名 hardware ethernet 00:0C:29:

7、F7:DB:70;#所绑定主机的mac地址 fixed-address 0;#所绑定的ip 完成之后重启服务：service dhcpd restart，若服务启动成功则可以使用一台客户机进行测试。这样一台最简单的DHCP服务器就架设完毕。3，租约文件在DHCP服务器上，/var/lib/dhcp/dhcpd.leases文件中存放着DHCP客户租期数据库。只要DHCP服务器能够成功启动，该数据库就可以自动创建。并且，所有通过该DHCP服务器分配到地址的客户机的地址信息都会存储于该文件中。该租期数据库文件经常被重建，但是不应该手工修改。另外如果主机上安装了两个网卡，但是只想让DHCP服务在其中

8、的一个网卡上监听，则需要配置DHCP服务器只在那个设备上启动。在/etc/sysconfig/dhcpd中，把网卡接口的名称添加到DHCPDARGS列表中。#Command line options here最后在客户端上使用netconfig命令设置客户端自动获取地址，完成后重启服务即可。rootlocalhost RPMS# cat /var/lib/dhcp/dhcpd.leases在服务器上查看已经分配出去的IP# All times in this file are in UTC (GMT), not your local timezone. This is# not a bug,

9、so please dont ask about it. There is no portable way to# store leases in the local timezone, so please dont request this as a# feature. If this is inconvenient or confusing to you, we sincerely# apologize. Seriously, though - dont ask.# The format of this file is documented in the dhcpd.leases(5) m

10、anual page.# This lease file was writtenby isc-dhcp-V3.0.1lease 00 starts 6 2007/03/17 04:36:31; ends 6 2007/03/17 10:36:31; binding state active; next binding state free; hardware ethernet 00:0c:29:67:57:c1;lease 99 starts 6 2007/03/17 04:37:13; ends 6 2007/03/17 10:37:13; binding state active; nex

11、t binding state free; hardware ethernet 00:0c:29:ef:cc:aa; uid 001000014)357314252; client-hostname cheshi-eeb7e489;嘿嘿成功。二，DHCP服务器源码包配置还是和上面的rpm包一样，我们这次用源码包来设置dhcp服务器，在配置之前首先准备工作：软件：gccdhcp-4.0.0.tar.gz1,先安装gccrootlocalhost cdrom# rpm -ivh gcc* -aid2，安装dhcp源码包首先确定系统上没安装rpm包rootlocalhost dhcp-3.0.2#

12、rpm -q dhcppackage dhcp is not installedrootlocalhost pub# tar -zxvf dhcp-4.0.0.tar.gz -C /usr/local/src/ rootlocalhost pub# cd /usr/local/src/dhcp-4.0.0/ rootlocalhost dhcp-4.0.0# ./configurerootlocalhost dhcp-4.0.0# makerootlocalhost dhcp-4.0.0# make installrootlocalhost dhcp-4.0.0# find / -name d

13、hcpd.conf#查找dhcp主配置文件/etc/log.d/conf/services/dhcpd.conf/usr/local/etc/dhcpd.conf/usr/local/src/dhcp-4.0.0/server/dhcpd.conf rootlocalhost dhcp-4.0.0# cp /usr/local/etc/dhcpd.conf /etc/dhcpd.conf3，dhcp服务器的配置rootlocalhost dhcp-4.0.0# cat /etc/dhcpd.conf # dhcpd.conf# Sample configuration file for ISC

14、 dhcpd# option definitions common to all supported networks.#option domain-name ;#option domain-name-servers , ;#default-lease-time 600;#max-lease-time 7200;# Use this to enble / disable dynamic dns updates globally.#ddns-update-style none;# If this DHCP server is the official DHCP server for the lo

15、cal# network, the authoritative directive should be uncommented.#authoritative;# Use this to send dhcp log messages to a different log file (you also# have to hack syslog.conf to complete the redirection).log-facility local7;# No service will be given on this subnet, but declaring it helps the # DHC

16、P server to understand the network topology.#subnet netmask # This is a very basic subnet declaration.#subnet netmask 24 # range 0 0;# option routers , ;# This declaration allows BOOTP clients to get dynamic addresses,# which we dont really recommend.#subnet 2 netmask 24 # range dynamic-bootp 0 0;#

17、option broadcast-address 1;# option routers ;# A slightly different configuration for an internal subnet.subnet netmask range 00 00; option domain-name-servers 53; option domain-name ; option routers 53; option subnet-mask ; option broadcast-address 55; default-lease-time 21600; max-lease-time 43200

18、;# Hosts which require special configuration options can be listed in# host statements. If no address is specified, the address will be# allocated dynamically (if possible), but the host-specific information# will still come from the host declaration.#host passacaglia # hardware ethernet 0:0:c0:5d:b

19、d:95;# filename vmunix.passacaglia;# server-name ;# Fixed IP addresses can also be specified for hosts. These addresses# should not also be listed as being available for dynamic assignment.# Hosts for which fixed IP addresses have been specified can boot using# BOOTP or DHCP. Hosts for which no fixe

20、d address is specified can only# be booted with DHCP, unless there is an address range on the subnet# to which a BOOTP client is connected which has the dynamic-bootp flag# set.host crazylinux hardware ethernet 00:0C:29:3B:68:25; fixed-address 50;# You can declare a class of clients and then do addr

21、ess allocation# based on that. The example below shows a case where all clients# in a certain class get addresses on the 10.17.224/24 subnet, and all# other clients get addresses on the 10.0.29/24 subnet.class foo match if substring (option vendor-class-identifier, 0, 4) = SUNW;shared-network 224-29

22、 subnet netmask option routers ; subnet netmask option routers ; pool allow members of foo; range 0 50; pool deny members of foo;range 0 30; 4，服务启动rootlocalhost dhcp-4.0.0# touch /var/db/dhcpd.leasesrootlocalhost dhcp-4.0.0# dhcpd三，RH AS4 dhcp中继代理如图所示：EEth0:48DHCP ServerDHCP ServerClientEth0:48Clien

23、tEth0:48DHCP RelayEEth1:45如图所示，配置dhcp server ip地址，eth0:48;网关为：45安装dhcp server，用linux RPM包安装；编辑 /etc/dhcpd.conf内容如下：ddns-update-styleinterim;ignoreclient-updates;optionsubnet-mask;optionnis-domain;optiondomain-name;optiontime-offset-18000;#EasternStandardTimedefault-lease-time259200;max-lease-time777

24、600;optiondomain-name-servers8,8;optionbroadcast-address55;#网通DNS服务器地址#下面配置超级作用域shared-neworkmynetsubnetnetmaskoptionrouters45rangedynamic-bootp00;subnetnetmask optionrouters48;rangedynamic-bootp00;编辑/etc/sysconfig/dhcpd ,DHCPDARGS=eth0启动dhcp服务，关闭防火墙。配置，dhcp relay ip 如下：eth0：48,网关可不设；eth1：45，网关为：48启

25、动ip_forward : echo “1”/proc/sys/net/ipv4/ip_forward（我在rhel4中实验不需要此步骤）或者在/etc/sysctl.conf中查看net.ipv4.ip_forward = 1#sysctl p立即生效安装dhcp软件编辑：/etc/sysconfig/dhcrelay INTERFACES=”eth0 eth1”DHCPSERVERS=”48”启动dhcrelay：service dhcrelay start,关闭防火墙用XP做 client去自动获取ip查看 dhcp server租期数据库：/var/lib/dhcp/dhcp.leas

26、es,可以看到已经租出的ip信息在XP可以获取到ip。四，使用ether-wake实现远程自动开机首先在客户机bios中设置网络唤醒功能连网记录客户机的MAC地址，关机在dhcp主机中下载ether-wake.c开始编译：#gcc -0 Wall o ether-wake ether-wake.c#./ether-wake 11:22:33:44:55:66 (唤醒主机)#./ether-wake u (查看帮助)五，DHCP原理两台连接到互联网上的电脑相互之间通信，必须有各自的IP地址，但由于现在的IP地址资源有限，宽带接入运营商不能做到给每个报装宽带的用户都能分配一个固定的IP地址（所谓固

27、定IP就是即使在你不上网的时候，别人也不能用这个IP地址，这个资源一直被你所独占），所以要采用DHCP方式对上网的用户进行临时的地址分配。也就是你的电脑连上网，DHCP服务器才从地址池里临时分配一个IP地址给你，每次上网分配的IP地址可能会不一样，这跟当时IP地址资源有关。当你下线的时候，DHCP服务器可能就会把这个地址分配给之后上线的其他电脑。这样就可以有效节约IP地址，既保证了你的通信，又提高IP地址的使用率。要申请固定IP上网，资费高很多的，所以对于普通客户，一般都是通过DHCP动态分配地址的。如果你不是商业用户，基本上是必须装DHCP才能上网的。DHCP(Dynamic Host Co

28、nfigure Protocol)，是被广泛应用于TCP/IP协议的网络中的动态主机配置协议，使用dhcp协议，有很多简单、易用的优点，主要表现在：网络管理员可以验证IP地址和其它配置参数，而不用去检查每个主机；DHCP不会同时租借相同的IP地址给两台主机；DHCP管理员可以约束特定的计算机使用特定的IP地址；可以为每个DHCP作用域设置很多选项；客户机在不同子网间移动时不需要重新设置IP地址。dhcp协议的工作流程1、DHCP客户机寻找DHCP服务器的阶段，可以称为发现阶段：DHCP客户机以广播方式（因为DHCP服务器的IP地址对于客户机来说是未知的）发送DHCP discover发现信息来寻找DHCP服务器，即向地址55发送特定的广播信息。网络上每一台安装了TCP/IP协议的主机都会接收到这种广播信息，但只有DHCP服务器才会做出响应。udp 68 udp 672、DHCP服务器提供IP地址的阶段，可以称为提供阶段：在网络中接收到DHCP discover发现信息的DHCP服务器都会做出响应，它从尚未出租的IP地址中挑选一个分配给DHCP客户机，向DHCP客户机发送一个包含出租的IP地址和其他设置的DHCP of