服务管理——DHCP-蒲公英云

一 DHCP相关知识

动态主机配置协议（Dynamic Host Configuration Protocol, DHCP）是一个局域网的网络协议，使用UDP协议工作，主要有两个用途：给内部网络或网络服务供应商自动分配IP地址，给用户或者内部网络管理员作为对所有计算机作中央管理的手段。简而言之，DHCP 是这样的服务器：服务器进行IP地址的分配、客户端自动获取IP。

我们先来看看DNS工作原理，如图一：

20130922093749031

图一 DNS工作原理

本文的虚拟机配置见图二

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图二虚拟机配置

二 dhcp——自动分配IP

--第一步，安装dhcp
[root@serv01 ~]# yum install dhcp* -y
[root@serv01 ~]# rpm -qa|grep dhcp
dhcp-4.1.1-19.P1.el6.x86_64
--第二步，修改配置文件
[root@serv01 ~]# vim /etc/dhcp/dhcpd.conf
[root@serv01 ~]# cat /etc/dhcp/dhcpd.conf
#
# DHCP Server Configuration file.
#  see /usr/share/doc/dhcp*/dhcpd.conf.sample
#  see 'man 5 dhcpd.conf'
#
subnet 192.168.1.0 netmask 255.255.255.0{
       range192.168.1.100 192.168.1.150;
}
--第三步，Windows环境下测试。
#Windows下注意事项：
#1.网卡：选择DHCP服务器对应的网卡
#2.把360卸载掉
#3.这是情况ip地址的命令：ifconfig/release、ifconfig /new
--第四步，Linux环境下测试，修改配置文件
[root@serv02 ~]# cat/etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE="eth0"
HWADDR="00:0C:29:6A:EC:97"
NM_CONTROLLED="yes"
ONBOOT="yes"
BOOTPROTO=dhcp
IPADDR=192.168.1.12
NETMASK=255.255.255.0
#发现IP改变，需要重新登录
[root@larrywen 0807]# ssh 192.168.1.51
The authenticity of host '192.168.1.51(192.168.1.51)' can't be established.
RSA key fingerprint is3e:bd:1e:76:c4:c7:b4:98:dc:95:fc:61:d7:a8:45:71.
Are you sure you want to continueconnecting (yes/no)? yes
Warning: Permanently added '192.168.1.51'(RSA) to the list of known hosts.
root@192.168.1.51's password:
Last login: Wed Aug  7 22:19:19 2013
[root@serv02 ~]#
[root@serv02 ~]# man 5 dhcpd.conf

三 dhcp——DNS和网关配置

--第一步，修改配置文件

[root@serv01 dhcp]# vim dhcpd.conf
[root@serv01 dhcp]# cat dhcpd.conf
#
# DHCP Server Configuration file.
#  see /usr/share/doc/dhcp*/dhcpd.conf.sample
#  see 'man 5 dhcpd.conf'
#
subnet 192.168.1.0 netmask 255.255.255.0 {
       range192.168.1.50 192.168.1.80;
       optiondomain-name-servers 8.8.8.8;
       optionrouters 192.168.1.1;
}
#检查配置文件是否正确
[root@serv01 dhcp]# /etc/init.d/dhcpdconfigtest
Syntax: OK

--第二步，重启服务

[root@serv01 dhcp]# /etc/init.d/dhcpdrestart
Shutting down dhcpd:                                       [  OK  ]
Starting dhcpd:                                            [  OK  ]

--第三步，Linux下测试

#Linux下
#重启服务
[root@serv02 ~]# /etc/init.d/networkrestart
Shutting down interface eth0:                              [  OK  ]
Shutting down loopback interface:                          [ OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0: 
Determining IP information for eth0...done.
                                                          [  OK  ]
#检查网关
[root@serv02 ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     0.0.0.0         255.255.255.0   U    0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U    1002   0        0 eth0
0.0.0.0         192.168.1.1     0.0.0.0         UG   0      0        0 eth0
#检查DNS
[root@serv02 ~]# cat /etc/resolv.conf
; generated by /sbin/dhclient-script
nameserver 8.8.8.8
#查看这个配置文件没有任何变化
[root@serv02 ~]# cat/etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE="eth0"
HWADDR="00:0C:29:6A:EC:97"
NM_CONTROLLED="yes"
ONBOOT="yes"
BOOTPROTO=dhcp
IPADDR=192.168.1.12
NETMASK=255.255.255.0

测试效果如图三

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图三 Linux下dhcp DNS和网关配置

--第四步，Windows环境下测试

这是没有网关和DNS时分配的IP地址：

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图四没有网关和DNS时分配的IP地址

这是添加网关和DNS时分配的IP地址：

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图五添加网关和DNS时分配的IP地址

四 dhcp——最大租约时间

--第一步，修改配置文件

[root@serv01 dhcp]# vim dhcpd.conf
[root@serv01 dhcp]# cat dhcpd.conf
#
# DHCP Server Configuration file.
#  see /usr/share/doc/dhcp*/dhcpd.conf.sample
#  see 'man 5 dhcpd.conf'
#
subnet 192.168.1.0 netmask 255.255.255.0 {
       range192.168.1.50 192.168.1.80;
       optiondomain-name-servers 8.8.8.8;
       optionrouters 192.168.1.1;
       max-lease-time60;
}

--第二步，重启服务

[root@serv01 dhcp]# /etc/init.d/dhcpdrestart
Shutting down dhcpd:                                       [  OK  ]
Starting dhcpd:                                            [  OK  ]

--第三步，Windows环境下测试

测试效果如图六：

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图六 DHCP 最大租约时间

五 dhcp——domain-name

--第一步，修改配置文件
[root@serv01 dhcp]# vim dhcpd.conf
[root@serv01 dhcp]# cat dhcpd.conf
#
# DHCP Server Configuration file.
#  see /usr/share/doc/dhcp*/dhcpd.conf.sample
#  see 'man 5 dhcpd.conf'
#
subnet 192.168.1.0 netmask 255.255.255.0 {
       range192.168.1.50 192.168.1.80;
       optiondomain-name "hongyi.com";
       optiondomain-name-servers 8.8.8.8;
       optionrouters 192.168.1.1;
       max-lease-time60;
}
--第二步，重启服务
[root@serv01 dhcp]# /etc/init.d/dhcpdrestart
Starting dhcpd:                                           [  OK  ]
--第三步，Linux环境下测试，重启服务，查看resolv.conf文件，发现自动生成了DNS服务器地址
[root@serv02 ~]# /etc/init.d/networkrestart
Shutting down interface eth0:                              [  OK  ]
Shutting down loopback interface:                          [  OK  ]
Bringing up loopback interface:                            [  OK  ]
Bringing up interface eth0: 
Determining IP information for eth0...done.
                                                          [  OK  ]
[root@serv02 ~]# cat /etc/resolv.conf
; generated by /sbin/dhclient-script
search hongyi.com host.com
nameserver 8.8.8.8

六 dhcp——fixed-address

--第一步，修改配置文件

[root@serv01 dhcp]# man 5 dhcpd.conf
[root@serv01 dhcp]# vim dhcpd.conf
[root@serv01 dhcp]# cat dhcpd.conf
#
# DHCP Server Configuration file.
#  see /usr/share/doc/dhcp*/dhcpd.conf.sample
#  see 'man 5 dhcpd.conf'
#
subnet 192.168.1.0 netmask 255.255.255.0 {
       range192.168.1.50 192.168.1.80;
       optiondomain-name "hongyi.com";
       optiondomain-name-servers 8.8.8.8;
       optionrouters 192.168.1.1;
       max-lease-time60;
}
host joe {
       hardwareethernet 00:0C:29:6A:EC:97;
       fixed-address 192.168.1.88;
}

--第二步，重启服务

[root@serv01 dhcp]# /etc/init.d/dhcpdrestart
Shutting down dhcpd:                                       [  OK  ]
Starting dhcpd:                                           [  OK  ]

--第三步，Linux环境下测试，如图七

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图七 DHCP fixed-address测试

七 dhcp中转

实现的功能：一台机器通过dhcp服务器从另一台机器中获得IP地址

网络拓扑结构图如图八所示：

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图八 DHCP 中转网络拓扑图

第一步，server 01修改配置文件

[root@serv01 dhcp]# vim dhcpd.conf
[root@serv01 dhcp]# cat dhcpd.conf
#
# DHCP Server Configuration file.
#  see /usr/share/doc/dhcp*/dhcpd.conf.sample
#  see 'man 5 dhcpd.conf'
#
subnet 192.168.1.0 netmask 255.255.255.0 {
       range192.168.1.60 192.168.1.65;
       optionrouters 192.168.1.1;
       optiondomain-name-servers 8.8.8.8;
       max-lease-time3600;
}
subnet 172.16.1.0 netmask 255.255.255.0 {
       range172.16.1.60 172.16.1.65;
       optionrouters 172.16.1.1;
       optiondomain-name-servers 8.8.4.4;
       max-lease-time3600;
}

第二步，serv01启动服务

[root@serv01 dhcp]# /etc/init.d/dhcpdrestart
Starting dhcpd:                                           [  OK  ]

第三步，添加默认路由（网关）

[root@serv01 dhcp]# ip route add defaultvia 192.168.1.13
#查看路由
[root@serv01 dhcp]# ip route
192.168.1.0/24 dev eth0  proto kernel scope link  src 192.168.1.11
169.254.0.0/16 dev eth0  scope link metric 1002
default via 192.168.1.13 dev eth0
[root@serv01 dhcp]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     0.0.0.0         255.255.255.0   U    0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U    1002   0        0 eth0
0.0.0.0         192.168.1.13    0.0.0.0         UG   0      0        0 eth0

第四步，server02测试

测试效果如图九，

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图九 DHCP 中转serv02测试

第五步，server03配置

#设置IP
[root@serv03 ~]# ip addr add 172.16.1.13brd 255.255.255.0 dev eth1
#启动网卡
[root@serv03 ~]# ip link set eth1 up
[root@serv03 ~]# ifconfig eth1
eth1     Link encap:Ethernet  HWaddr00:0C:29:BD:08:0F 
         inet addr:172.16.1.13 Bcast:255.255.255.0 Mask:255.255.255.255
         inet6 addr: fe80::20c:29ff:febd:80f/64 Scope:Link
         UP BROADCAST RUNNING MULTICAST MTU:1500  Metric:1
         RX packets:0 errors:0 dropped:0 overruns:0 frame:0
         TX packets:25 errors:0 dropped:0 overruns:0 carrier:0
         collisions:0 txqueuelen:1000
         RX bytes:0 (0.0 b)  TX bytes:4247(4.1 KiB)
#编辑文件
[root@serv03 ~]# vim/etc/sysconfig/dhcrelay
[root@serv03 ~]# cat/etc/sysconfig/dhcrelay
# Command line options here
DHCRELAYARGS=""
# DHCPv4 only
INTERFACES="eth0 eth1"
# DHCPv4 only
DHCPSERVERS="192.168.1.11"

第六步，Window 01测试

测试效果如图十

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图十 dhcp中转Windows测试

第七步，要想ping通，这样修改

1.serv01修改配置

[root@serv01 dhcp]# cat dhcpd.conf
#
# DHCP Server Configuration file.
#  see /usr/share/doc/dhcp*/dhcpd.conf.sample
#  see 'man 5 dhcpd.conf'
#
subnet 192.168.1.0 netmask 255.255.255.0 {
       range192.168.1.60 192.168.1.65;
       optionrouters 192.168.1.1;
       optiondomain-name-servers 8.8.8.8;
       max-lease-time3600;
}
subnet 172.16.1.0 netmask 255.255.255.0 {
       range172.16.1.60 172.16.1.65;
       optionrouters 172.16.1.13;
       optiondomain-name-servers 8.8.4.4;
       max-lease-time3600;
}

2.serv01重启服务

[root@serv01 dhcp]# /etc/init.d/dhcpd restart

3.serv01打开IP转发

[root@serv01 dhcp]# sysctl -wnet.ipv4.ip_forward=1

4.serv03添加默认路由

#注意：新添加的IP地址不一定会给你添加默认路由，所以要全方面地检查，台智能化的东西不要太依赖。
[root@serv03 ~]# ip route add 172.16.1.0/24dev eth1
[root@serv03 ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.1.0     0.0.0.0         255.255.255.0   U    0      0        0 eth0
172.16.1.0      0.0.0.0         255.255.255.0   U    0      0        0 eth1

5.测试（serv01 ping Win 01）

#serv01 ping Win 01
[root@serv01 dhcp]# ping 172.16.1.60
PING 172.16.1.60 (172.16.1.60) 56(84) bytesof data.
64 bytes from 172.16.1.60: icmp_seq=1ttl=127 time=0.543 ms
64 bytes from 172.16.1.60: icmp_seq=2ttl=127 time=0.479 ms
64 bytes from 172.16.1.60: icmp_seq=3ttl=127 time=0.657 ms
^C
--- 172.16.1.60 ping statistics ---
3 packets transmitted, 3 received, 0%packet loss, time 2677ms
rtt min/avg/max/mdev =0.479/0.559/0.657/0.078 ms

6.测试（Win01 ping Serv01）

测试效果如图十一：

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图十一 Windows01ping通Serv01

7.注意事项：

#还要注意把Linux和Windows的防火墙关闭

#注意：使用ip命令添加的IP地址没有默认路由，使用ifconfig命令才有

八参考资料

百度百科

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