服务管理——DHCP

怼烎@ 2022-08-30 05:16 221阅读 0赞

## 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

![SouthEast][]

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

![SouthEast 1][]

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：

![SouthEast 2][]

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：

![SouthEast 3][]

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

\--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：

![SouthEast 4][]

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

![SouthEast 5][]

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：

![SouthEast 6][]

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，

![SouthEast 7][]

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

![SouthEast 8][]

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：

![SouthEast 9][]

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

>     我的邮箱：wgbno27@163.com   新浪微博：@Wentasy27         
>       微信公众平台：JustOracle（微信号：justoracle）
>       数据库技术交流群：336882565（加群时验证 From CSDN XXX）
>       By Larry Wen

<table style="border-bottom:#48c5db 5px double; border-left:#48c5db 5px double; padding-bottom:5px; background-color:black; padding-left:5px; border-spacing:0; width:100%; padding-right:30px; height:90px; border-top:#48c5db 5px double; border-right:#48c5db 5px double; padding-top:5px"> 
 <tbody> 
  <tr> 
   <td><img alt="katoon" src="https://img-my.csdn.net/uploads/201301/06/1357456262_5409.jpg" style="height:80px"></td> 
   <td style="text-align:right"><a title="新浪微博求粉 ^_^" href="http://weibo.com/wentasy" rel="nofollow"><img title="新浪微博求粉 ^_^" alt="Sina" src="https://img-my.csdn.net/uploads/201210/26/1351182273_5476.png.thumb.jpg" style="height:40px"></a>&nbsp;<a title="我的CSDN博客——HelloWorld" href="http://blog.csdn.net/Wentasy" rel="nofollow"><img title="我的CSDN博客——HelloWorld" alt="CSDN" src="https://img-my.csdn.net/uploads/201210/26/1351182268_8254.png.thumb.jpg" style="height:40px"></a></td> 
  </tr> 
  <tr> 
   <td style="text-align:right; font-family:microsoft yahei; color:white; font-size:12px"> <a title="我的CSDN博客——HelloWorld" href="http://blog.csdn.net/Wentasy" rel="nofollow">@Wentasy</a> 博文仅供参考，欢迎大家来访。如有错误之处，希望批评指正。原创博文如需转载请注明出处，谢谢 :) [CSDN博客]</td> 
  </tr> 
 </tbody> 
</table>

[20130922093749031]: /images/20220829/15c1b56f5bf64bb781641b2a4d0a873f.png
[SouthEast]: /images/20220829/4c3c47ba706b40ea8e44fcc2ce8f1895.png
[SouthEast 1]: /images/20220829/12144d6c5f5945d5a5b06baf06d0df6e.png
[SouthEast 2]: /images/20220829/cd9e9706d0b546ad812e641c38ccbf5c.png
[SouthEast 3]: /images/20220829/32188150b95b4d96b99d730cb43b3220.png
[SouthEast 4]: /images/20220829/3624434ef86d457d9145a30ecca51008.png
[SouthEast 5]: /images/20220829/71a5860cf07e45e395069ae83512c153.png
[SouthEast 6]: /images/20220829/28af52431be8452facbe945e0c075d8e.png
[SouthEast 7]: /images/20220829/506b3e15ac494587a9765af84d30d796.png
[SouthEast 8]: /images/20220829/255c3aa4f46c40d696ba5db2da2d252e.png
[SouthEast 9]: /images/20220829/7bd7f0a345334c91bbbb9165ff185b56.png