1、DHCP工作過程
dhcp discover \\客戶端請求服務器器提供地址
dhcp offer \\服務器提供ip地址
dhcp request \\客戶端租用ip地址
dhcp ack \\服務器確認客戶端的租用
2、安裝dhcp軟件包
# yum install dhcpd
# cd /etc/dhcpd
# cp /usr/share/doc/dhcp-4.1.1/dhcpd.conf.sample ./dhcpd.conf
3、配置DHCP
基本配置內容
確定ip地址所在的網絡
設置需要分配的ip地址范圍
設置分配ip地址的子網掩碼
設置網關ip地址
設置dns地址
設置租期時間(默認租期時間和最大租期時間)
地址綁定(給一台設備分配一個固定的ip地址)
# vim dhcpd.conf
option domain-name "sxjy.com";
option domain-name-servers 8.8.8.8,202.103.96.112;
default-lease-time 3600;
max-lease-time 72000;
log-facility local7;
shared-network sxjy {
subnet 172.16.10.0 netmask 255.255.255.0 {
range 172.16.10.2 172.16.10.100;
range 172.16.10.200 172.16.10.250;
option routers 172.16.10.1;
option broadcast-address 172.16.10.255;
default-lease-time 7200;
max-lease-time 15400;
}
subnet 172.16.20.0 netmask 255.255.255.0 {
range 172.16.20.2 172.16.20.100;
range 172.16.20.200 172.16.20.250;
option routers 172.16.20.1;
option broadcast-address 172.16.20.255;
}
host ftp.sxjy.com {
hardware ethernet 00:0C:29:B6:DF:5E;
fixed-address 172.16.10.10;
fixed-address 172.16.10.10;
}
}
練習:用三台虛擬機,其中一台為服務器,兩台為客戶機,要求兩台客戶機能獲取到服務器分配的不同網段的地址,例如一台
獲取的地址為192.168.1.10/24,另一台為192.168.2.10/24,具體地址段可以自己定義,但不能給其它人分配
ip地址,在服務器上抓包觀察ip分配情況
4、DHCP地址綁定
host ftp.sxjy.com {
hardware ethernet 00:0C:29:B6:DF:5E;
fixed-address 192.168.10.10;
}
5、DHCP中繼配置
(1)開啟中繼服務器的路由轉發功能
# vim /etc/sysctl.conf
net.ipv4.ip_forward = 1
# sysctl -p
(2)設置中繼選項
# vim /etc/sysconfig/dhcrelay
INTERFACES="eth0 eth1"
DHCPSERVERS="172.16.10.1"
(3)啟動dhcp中繼服務
# service dhcrelay start
6、windows客戶端的使用
ipconfig /renew \\重新獲取ip地址
ipconfig /release \\釋放ip地址
# dhclinet eth0
DHCP中繼實驗步驟：
(1)設置單網卡DHCP服務器，其上配置自己所在網段內的地址池，同時也需要配置其它網段地址池（該地址池中必須包含有option routers選項）。
[root@server2 ~]# cat /etc/dhcp/dhcpd.conf
ddns-update-style none;
option domain-name "sxjy.com";
option domain-name-servers 1.1.1.1;
default-lease-time 6000;
max-lease-time 7200;
log-facility local7;
#shared-network haha {
subnet 192.168.3.0 netmask 255.255.255.0 {
range 192.168.3.10 192.168.3.20; //其他網絡的地址池
option domain-name-servers 2.2.2.2;
option routers 192.168.3.254; //該網關地址一定要指定
}
subnet 192.168.2.0 netmask 255.255.255.0 {
range 192.168.2.10 192.168.2.20; //該地址池為DHCP服務器自己所在網絡的地址池
option domain-name-servers 2.2.2.2;
option routers 192.168.2.100;
}
自己的網卡為192.168.2.0網絡
[root@server2 ~]# ip add show eth1
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:17:18:20 brd ff:ff:ff:ff:ff:ff
inet 192.168.2.100/24 brd 192.168.2.255 scope global eth1\
同時自己的網關還需要指向路由主機:
[root@server2 ~]# route|grep default
default 192.168.2.254 0.0.0.0 UG 0 0 0 eth1
(2)設置路由主機，同時承擔DHCP中繼的角色
該路由器連接DHCP服務器的網卡(eth0)IP為192.168.2.254，另一張網卡(eth1)必須為192.168.3.254(與步驟1中的地址池設置相匹配)
a、開啟中繼服務器的路由轉發功能
# vim /etc/sysctl.conf
net.ipv4.ip_forward = 1
# sysctl -p
b、設置中繼選項
# vim /etc/sysconfig/dhcrelay
INTERFACES="eth0 eth1"
DHCPSERVERS="172.16.10.1"
啟動dhcrelay: service dhcrelay start
(3)設置客戶端
該客戶端的網卡鏈接路由器的eth1：
dhclient -r eth0;dhclient eth0
PS:路由器eht1和客戶機eth0共用SW1的局域網。路由器eth0和DHCP服務器共用host-only的局域網。
路由器的DHCP
DHCP服務器的配置
Router(config)#interface fastEthernet 0/0
Router(config-if)#no shutdown
Router(config-if)#ip address 192.168.10.1 255.255.255.0
Router(config-if)#exit
Router(config)#ip dhcp pool xixi
Router(dhcp-config)#network 192.168.20.0 255.255.255.0
Router(dhcp-config)#default-router 192.168.20.1
Router(dhcp-config)#dns-server 8.8.8.8
Router(dhcp-config)#exit
Router(dhcp-config)#network 192.168.10.0 255.255.255.0
Router(dhcp-config)#default-router 192.168.10.2
Router(dhcp-config)#dns-server 8.8.8.8
Router(dhcp-config)#exit
Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.10.2
中繼代理的配置
Router(config)#interface fastEthernet 0/0
Router(config-if)#no shutdown
%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/0, changed state to up
Router(config-if)#ip address 192.168.10.2 255.255.255.0
Router(config)#interface fastEthernet 0/1
Router(config-if)#no shutdown
Router(config-if)#ip address 192.168.20.1 255.255.255.0
Router(config-if)#ip helper-address 192.168.10.1
測試
主機上
PC>ipconfig /release
IP Address......................: 0.0.0.0
Subnet Mask.....................: 0.0.0.0
Default Gateway.................: 0.0.0.0
DNS Server......................: 0.0.0.0
PC>ipconfig /renew
IP Address......................: 192.168.20.2
Subnet Mask.....................: 255.255.255.0
Default Gateway.................: 192.168.20.1
DNS Server......................: 8.8.8.8