主配文件：/etc/dhcp/dhcp.conf
作用域设置（subnet）
租约文件的路径：/var/lib/dhcpd/dhcpd.leases

DHCP配置文件分为全局和作用域，在subnet里是是作用域，在subnet外是全局

配置文件详解：

  1. [root@zutuanxue ~]# cat /etc/dhcp/dhcpd.conf
  2. # #号代表注释
  3. # DHCP服务配置文件分为全局配置和作用域配置，很好区分：subnet的就是作用域 不在subnet里面的就是全局设置。
  4. # dhcpd.conf
  5. #
  6. # Sample configuration file for ISC dhcpd
  7. #
  9. #DNS全局选项，指定DNS服务器的地址，可以是IP，也可以是域名。
  10. # option definitions common to all supported networks...
  11. # DNS的域名
  12. option domain-name "example.org";
  14. #具体的DNS服务器
  15. option domain-name-servers ns1.example.org, ns2.example.org;
  17. #默认租约为600s
  18. default-lease-time 600;
  19. #最大租约为7200s，客户机会在default-lease-time快到期时向服务器续租，如果此时客户机死机/重启，而默认租约时间到期了，服务器并不会立即回收IP地址，而是等到最大租约时间到期，客户机还没有过来续约，才会回收IP地址。
  20. max-lease-time 7200;
  22. #动态DNS更新方式(none:不支持；interim:互动更新模式；ad-hoc:特殊更新模式)
  23. # Use this to enble / disable dynamic dns updates globally.
  24. #ddns-update-style none;
  26. #如果该DHCP服务器是本地官方DHCP就将此选项打开，避免其他DHCP服务器的干扰。
  27. #当一个客户端试图获得一个不是该DHCP服务器分配的IP信息，DHCP将发送一个拒绝消息，而不会等待请求超时。当请求被拒绝，客户端会重新向当前DHCP发送IP请求获得新地址。保证IP是自己发出去的
  28. #
  29. # If this DHCP server is the official DHCP server for the local
  30. # network, the authoritative directive should be uncommented.
  31. #authoritative;
  33. # Use this to send dhcp log messages to a different log file (you also
  34. # have to hack syslog.conf to complete the redirection).
  35. # 日志级别
  36. log-facility local7;
  38. # No service will be given on this subnet, but declaring it helps the 
  39. # DHCP server to understand the network topology.
  41. #作用域相关设置指令
  42. #subnet 定义一个作用域
  43. #netmask 定义作用域的掩码
  44. #range 允许发放的IP范围
  45. #option routers 指定网关地址
  46. #option domain-name-servers 指定DNS服务器地址
  47. #option broadcast-address 广播地址
  48. #
  49. #
  50. #案例:定义一个作用域 网段为10.152.187.0 掩码为255.255.255.0
  51. #此作用域不提供任何服务
  52. subnet 10.152.187.0 netmask 255.255.255.0 {
  53. }
  55. # This is a very basic subnet declaration.
  57. #案例:定义一个基本的作用域
  58. #网段10.254.239.0 掩码255.255.255.224
  59. #分发范围10.254.239.10-20
  60. #网关为rtr-239-0-1.example.org, rtr-239-0-2.example.org
  61. subnet 10.254.239.0 netmask 255.255.255.224 {
  62.   range 10.254.239.10 10.254.239.20;
  63.   option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
  64. }
  66. # This declaration allows BOOTP clients to get dynamic addresses,
  67. # which we don't really recommend.
  68. #案例:允许采用bootp协议的客户端动态获得地址
  69. #bootp DHCP的前身
  70. #BOOTP用于无盘工作站的局域网中，可以让无盘工作站从一个中心服务器上获得IP地址。通过BOOTP协议可以为局域网中的无盘工作站分配动态IP地址，
  71. #这样就不需要管理员去为每个用户去设置静态IP地址。
  72. subnet 10.254.239.32 netmask 255.255.255.224 {
  73.   range dynamic-bootp 10.254.239.40 10.254.239.60;
  74.   option broadcast-address 10.254.239.31;
  75.   option routers rtr-239-32-1.example.org;
  76. }
  79. #案例:一个简单的作用域案例
  80. # A slightly different configuration for an internal subnet.
  81. subnet 10.5.5.0 netmask 255.255.255.224 {
  82.   range 10.5.5.26 10.5.5.30;
  83.   option domain-name-servers ns1.internal.example.org;
  84.   option domain-name "internal.example.org";
  85.   option routers 10.5.5.1;
  86.   option broadcast-address 10.5.5.31;
  87.   default-lease-time 600;
  88.   max-lease-time 7200;
  89. }
  91. # Hosts which require special configuration options can be listed in
  92. # host statements.   If no address is specified, the address will be
  93. # allocated dynamically (if possible), but the host-specific information
  94. # will still come from the host declaration.
  95. #
  96. #保留地址:可以将指定的IP分发给指定的机器，根据网卡的MAC地址来做触发
  97. #host: 启用保留。
  98. #hardware:指定客户端的mac地址
  99. #filename:指定文件名
  100. #server-name:指定下一跳服务器地址
  101. #fixed-address: 指定保留IP地址
  102. #
  103. #
  104. #案例:这个案例中分发给客户端的不是IP地址信息，而是告诉客户端去找toccata.fugue.com服务器，并且下载vmunix.passacaglia文件
  105. host passacaglia {
  106.   hardware ethernet 0:0:c0:5d:bd:95;
  107.   filename "vmunix.passacaglia";
  108.   server-name "toccata.fugue.com";
  109. }
  111. # Fixed IP addresses can also be specified for hosts.   These addresses
  112. # should not also be listed as being available for dynamic assignment.
  113. # Hosts for which fixed IP addresses have been specified can boot using
  114. # BOOTP or DHCP.   Hosts for which no fixed address is specified can only
  115. # be booted with DHCP, unless there is an address range on the subnet
  116. # to which a BOOTP client is connected which has the dynamic-bootp flag
  117. # set.
  118. # 案例:保留地址，将指定IP(fantasia.fugue.com对应的IP)分给指定客户端网卡(MAC:08:00:07:26:c0:a5)
  119. host fantasia {
  120.   hardware ethernet 08:00:07:26:c0:a5;
  121.   fixed-address fantasia.fugue.com;
  122. }
  124. #超级作用域
  125. #超级作用域是DHCP服务中的一种管理功能，使用超级作用域，可以将多个作用域组合为单个管理实体。
  126. # You can declare a class of clients and then do address allocation
  127. # based on that.   The example below shows a case where all clients
  128. # in a certain class get addresses on the 10.17.224/24 subnet, and all
  129. # other clients get addresses on the 10.0.29/24 subnet.
  132. #在局域网中，可以配置策略根据各个机器的具体信息分配IP地址和其他的网络参数，客户机的具体信息：客户机能够给dhcp服务提供的信息由有两个，
  133. #第一个就是网卡的dhcp-client-identifier（mac地址），
  134. #第二个就是设备的vendor-class-identifier。
  135. #管理员可以根据这两个信息给不同的机器分组。
  137. #案例:
  138. #按client某种类型分组DHCP,而不是按物理接口网段
  139. #例子: SUNW 分配地址段10.17.224.0/24
  140. # 非SUNW的主机,分配地址段10.0.29.0/24
  141. #定义一个dhcp类:foo
  142. #request广播中vendor-class-identifier字段对应的值前四个字节如果是"SUNW",则视合法客户端.
  143. class "foo" {
  144.   match if substring (option vendor-class-identifier, 0, 4) = "SUNW";
  145. }
  147. #定义一个超级作用域: 224-29
  148. shared-network 224-29 {
  149. #定义第一个作用域
  150.   subnet 10.17.224.0 netmask 255.255.255.0 {
  151.     option routers rtr-224.example.org;
  152.   }
  153. #定义第二个作用域
  154.   subnet 10.0.29.0 netmask 255.255.255.0 {
  155.     option routers rtr-29.example.org;
  156.   }
  158. #关连池,如果客户端匹配foo类，将获得该池地址
  159.   pool {
  160.     allow members of "foo";
  161.     range 10.17.224.10 10.17.224.250;
  162.   }
  163. #关连池,如果客户端配置foo类，则拒绝获得该段地址
  164.   pool {
  165.     deny members of "foo";
  166.     range 10.0.29.10 10.0.29.230;
  167.   }
  168. }