原理介绍:DHCP(Dynamic Host Configuration Protocol)动态主机设置协议(udp),主要用于分配地址
工作模式:
1.手工 manaul Allocation
Server –地址池 (ip mac)
2.自动 automatic Allocation
Server –地址池(起始地址-结束地址)永久
3.动态方式 Dynamic Allocation
Server –地址池(起始地址-结束地址)租期
客户端获取地址过程
1. Dhcpdisrecover(广播) ->寻找
2. dhcpoffer (广播) <- 提供地址
3. dhcprequest (广播) -> 请求
4. dhcpack <- 确认
更新过程
1. 重新启动 dhcprequest
2. 50% dhcprequest 87.5% dhcpdisrecover(4步骤)
100% 终止使用 169.25.xx
案例应用1:动态分配,ip地址绑定,排除
拓扑图:
地址分配方案:
vim /etc/dhcpd.conf
默认情况下此文件是空的,可读取模板文件
:r /usr/share/doc/dhcp-3.0.5/dhcpd.conf.sample
ddns-update-style interim;
ignore client-updates;
subnet 192.168.5.0 netmask 255.255.255.0 {
option routers 192.168.5.1; #网关
option subnet-mask 255.255.255.0; #掩码
option domain-name "tec.com"; #域名
option domain-name-servers 222.88.88.88,222.85.85.85; #dns
range dynamic-bootp 192.168.5.2 192.168.5.254; #地址池
default-lease-time 21600; #租约时间
max-lease-time 43200;
}
绑定:
# 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; #mac
fixed-address 207.175.42.254; #绑定的ip
}
排除:
分段书写,如排除2.100
range dynamic-bootp 192.168.2.1 192.168.2.99;
range dynamic-bootp 192.168.2.101 192.168.2.254;
案例应用2:DHCP中继
router会隔离广播,需做dhcp中继,这里用linux模拟路由器,应开启linux的数据包转发功能
拓扑图:
地址方案分配:
服务器配置:
1.安装
rpm -ivh dhcp-3.0.5-23.el5.i386.rpm
2.编辑配置脚本
vim /etc/dhcpd.conf
#
ddns-update-style interim;
ignore client-updates;
subnet 192.168.2.0 netmask 255.255.255.0 {
}
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 domain-name "tec.com";
option domain-name-servers 222.88.88.88,222.85.85.85;
option time-offset -18000; # Eastern Standard Time
range dynamic-bootp 192.168.3.2 192.168.3.254;
default-lease-time 21600;
max-lease-time 43200;
}
subnet 192.168.4.0 netmask 255.255.255.0 {
# --- default gateway
option routers 192.168.4.1;
option subnet-mask 255.255.255.0;
option domain-name "mark.com";
option domain-name-servers 222.88.88.88,222.85.85.85;
option time-offset -18000; # Eastern Standard Time
range dynamic-bootp 192.168.4.2 192.168.4.254;
default-lease-time 21600;
max-lease-time 43200;
}
service dncpd restart
ROUTER :
1.安装 rpm -ivh dhcp-3.0.5-23.el5.i386.rpm
2.编辑配置文件
vim /etc/sysconfig/dhcrelay
3.开启数据包转发功能
echo “1”>/proc/sys/net/ipv4/ip_forward
或者 vim /etc/sysctl.conf
net.ipv4.ip_forward =1 改为“1”
sysctl –p
4.确保各项服务已开启,如有必要请重启
chkconfig dhcrelay on
Service network restart
Service dhcrelay start
验证:
市场部分到的地址:
技术部分到的地址:
(linux一般从地址池最后一个开始分配)
小结:
请注意dhcp配置文件书写正确,否者无法开启服务
配置完各项服务后,请重启,确保服务正常运行