怎样设置多网段dhcpd？

首先你要把网卡搞清楚，然后才可以进到下一步

第一步：创建

VLAN

Switch>Vlan Database

Switch(Vlan)>Vlan 2 Name server

Switch(Vlan)>Vlan 3 Name work01

Switch(vlan)>Vlan 4 Name work02

第二步：启用DHCP中继代理：

关键一步，缺少以下两条命令，VLAN中使用“IP HELPER

-ADDRESS DHCP

服务器地址”指定DHCP服务器，客户机仍然不能获得IP地址

Switch>Enable

Switch#Config t

Switch(Config)Service Dhcp

Switch(Config)Ip Dhcp Relay Information Option

第三步：设置

VLAN IP

地址：

Switch(Config)>Int Vlan 2

Switch(Config-vlan)Ip Address 192.168.2.1 255.255.255.0

Switch(Config-vlan)No Shut

Switch(Config-vlan)>Int Vlan 3

Switch(Config-vlan)Ip Address 192.168.3.1 255.255.255.0

Switch(Config-vlan)No Shut

Switch(Config-vlan)>Int Vlan 4

Switch(Config-vlan)Ip Address 192.168.4.1 255.255.255.0

Switch(Config-vlan)No Shut

Switch(Config-vlan)Exit

注意：由于此时没有将端口分配置到VLAN2，3，4，所以各VLAN会DOWN掉，待将端口分配到各VLAN后，VLAN会起来

第四步：设置端口全局参数

Switch(Config)Interface Range Fa 0/1 - 24

Switch(Config-if-range)Switchport Mode Access

Switch(Config-if-range)Spanning-tree Portfast

第五步：将端口添加到VLAN2，3，4中 /*将端口1-8添加到VLAN 2*/

Switch(Config)Interface Range Fa 0/1 - 8

Switch(Config-if-range)Switchport Access Vlan 2 *

将端口9-16

添加到VLAN 3*/ Switch(Config)Interface Range Fa 0/9 - 16

Switch(Config-if-range)Switchport Access Vlan 3 *

将端口17-24添加到VLAN 4*/

Switch(Config)Interface Range Fa 0/17 - 24

Switch(Config-if-range)Switchport Access Vlan 4

Switch(Config-if-range)Exit /*经过这一步后，各VLAN会起来

第六步：在VLAN3和4中设定DHCP服务器地址

VLAN 2中不须指定DHCP服务器地址

Switch(Config)Int Vlan 3

Switch(Config-vlan)Ip Helper-address 192.168.2.10

Switch(Config)Int Vlan 4

Switch(Config-vlan)Ip Helper-address 192.168.2.10

第七步启用路由

路由启用后各VLAN间主机可互相访问,若需进一步控制访问权限,则需应用到访问控制列表

Switch(Config)Ip Routing

第八步：结束并保存配置

Switch(Config-vlan)End

Switch#Copy Run Start

DHCP多作用域设置

DHCP服务器使用单一的作用域，大部分时间能够满足网络的需求，但是有些特殊情况下，按照网络规划我们需要配置多作用域。

网络中如果计算机和其他设备数量增加，IP地址需要进行扩容才能满足需求。小型网络可以对所有设备重新分配IP地址，其网络内部客户机和服务器数量较少，实现起来比较简单。但如果是一个大型网络，重新配置整个网络的IP地址是不明智的，如果操作不当，可能会造成通信暂时中断以及其他网络故障。我们可以通过多作用域的设置，即DHCP服务器发布多个作用域实现IP地址增容的目的。

公司IP地址规划为192.168.2.0/24网段，可以容纳254台设备，使用DHCP服务器建立一个192.168.2.0网段的作用域，动态管理网络IP地址，但网络规模扩大到500台机器，显然一个C类网的地址无法满足要求了。这时，可以再为DHCP服务器添加一个新作用域，管理分配192.168.3.0/24网段的IP地址，为网络增加254个新的IP地址，这样既可以保持原有IP地址的规划，又可以扩容现有的网络IP地址。

（1）简单实现DHCP多作用域

对于多作用域的配置，必须保证DHCP服务器能够侦听所有子网客户机的请求信息，下面将讲解配置多作用域的基本方法，为DHCP添加多个网卡连接每个子网，并发布多个作用域的声明。

注意：划分子网时，如果选择直接配置多作用域实现动态IP分配的任务，则必须要为DHCP服务器添加多块网卡，并配置多个IP地址，否则DHCP服务器只能分配与其现有网卡IP地址对应网段的作用域。

采用双网卡实现两个作用域

1）网卡配置IP地址

DHCP服务器有多块网卡时，需要使用ifconfig命令为每块网卡配置独立的IP地址，但要注意，IP地址配置的网段要与DHCP服务器发布的作用域对应哈~

ifconfig eth0 192.168.2.1 netmask 255.255.255.0

ifconfig eth1 192.168.3.1 netmask 255.255.255.0

2）编辑dhcpd.conf主配置文件

当DHCP服务器网络环境搭建完毕后，我们可以编辑dhcpd.conf主配置文件完成多作用域的设置。

ddns-update-style none

ignore client-updates

subnet 192.168.2.0 netmask 255.255.255.0 {

# --- default gateway

option routers 192.168.2.1

option subnet-mask 255.255.255.0

option nis-domain "domain.org"

option domain-name "domain.org"

option domain-name-servers 192.168.2.2

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-bootp 192.168.2.50 192.168.2.250

default-lease-time 21600

max-lease-time 43200

# 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

}

}

subnet 192.168.3.0 netmask 255.255.255.0 {

# --- default gateway

option routers 192.168.3.1

option subnet-mask 255.255.255.0

option nis-domain "domain.org"

option domain-name "domain.org"

option domain-name-servers 192.168.2.2

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-bootp 192.168.3.50 192.168.3.250

default-lease-time 21600

max-lease-time 43200

max-lease-time 43200

}

保存退出哈~

3）测试验证

重启DHCP服务后检查系统日志，检测配置是否成功，使用tail命令动态显示日志信息。

tail -F /etc/log/messages

经过设置，对于DHCP服务器将通过eth0和eth1两块网卡侦听客户机的请求，并发送相应的回应。

Jan 19 16:02:51 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da via eth1

Jan 19 16:02:51 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da via eth0

Jan 19 16:02:52 rhel5 dhcpd: DHCPOFFER . 192.168.3.250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:52 rhel5 dhcpd: DHCPOFFER . 192.168.2.250 to 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:52 rhel5 dhcpd: DHCPREQUEST for 192.168.3.250 (192.168.3.1) from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:52 rhel5 dhcpd: DHCPACK . 192.168.3.250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:52 rhel5 dhcpd: DHCPREQUEST for 192.168.3.250 (192.168.3.1) from 00:19:21:bd:a3:da (mis) via eth0: ignored (not authoritative).

Jan 19 16:02:53 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:53 rhel5 dhcpd: DHCPOFFER . 192.168.3.250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:53 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:53 rhel5 dhcpd: DHCPOFFER . 192.168.2.250 to 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:53 rhel5 dhcpd: DHCPREQUEST for 192.168.3.250 (192.168.3.1) from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:53 rhel5 dhcpd: DHCPACK . 192.168.3.250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:53 rhel5 dhcpd: DHCPREQUEST for 192.168.3.250 (192.168.3.1) from 00:19:21:bd:a3:da (mis) via eth0: ignored (not authoritative).

Jan 19 16:02:54 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:54 rhel5 dhcpd: DHCPOFFER . 192.168.3.250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:54 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:54 rhel5 dhcpd: DHCPOFFER . 192.168.2.250 to 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:54 rhel5 dhcpd: DHCPREQUEST for 192.168.3.250 (192.168.3.1) from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:54 rhel5 dhcpd: DHCPACK . 192.168.3.250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:54 rhel5 dhcpd: DHCPREQUEST for 192.168.3.250 (192.168.3.1) from 00:19:21:bd:a3:da (mis) via eth0: ignored (not authoritative).

Jan 19 16:02:55 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:55 rhel5 dhcpd: DHCPOFFER . 192.168.3.250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:55 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:55 rhel5 dhcpd: DHCPOFFER . 192.168.2.250 to 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:55 rhel5 dhcpd: DHCPREQUEST for 192.168.3.250 (192.168.3.1) from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:55 rhel5 dhcpd: DHCPACK . 192.168.3.250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:55 rhel5 dhcpd: DHCPREQUEST for 192.168.3.250 (192.168.3.1) from 00:19:21:bd:a3:da (mis) via eth0: ignored (not authoritative).

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