华为DHCP-Snooping配置实例

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1、DHCP Snooping配置介绍DHCP Snooping的原理和配置方法，并给出配置举例。配置DHCP Snooping的攻击防范功能示例组网需求如图9-13所示，SwitchA与SwitchB为接入设备，SwitchC为DHCP Relay。Client1与Client2分别通过GE0/0/1与GE0/0/2接入SwitchA，Client3通过GE0/0/1接入SwitchB，其中Client1与Client3通过DHCP方式获取IPv4地址，而Client2使用静态配置的IPv4地址。网络中存在非法用户的攻击导致合法用户不能正常获取IP地址，管理员希望能够防止网络中针对DHCP的攻击

2、，为DHCP用户提供更优质的服务。图9-13 配置DHCP Snooping的攻击防范功能组网图 配置思路采用如下的思路在SwitchC上进行配置。1. 使能DHCP Snooping功能并配置设备仅处理DHCPv4报文。 2. 配置接口的信任状态，以保证客户端从合法的服务器获取IP地址。 3. 使能ARP与DHCP Snooping的联动功能，保证DHCP用户在异常下线时实时更新绑定表。 4. 使能根据DHCP Snooping绑定表生成接口的静态MAC表项功能，以防止非DHCP用户攻击。 5. 使能对DHCP报文进行绑定表匹配检查的功能，防止仿冒DHCP报文攻击。 6. 配置DHCP报文上

3、送DHCP报文处理单元的最大允许速率，防止DHCP报文泛洪攻击。 7. 配置允许接入的最大用户数以及使能检测DHCP Request报文帧头MAC与DHCP数据区中CHADDR字段是否一致功能，防止DHCP Server服务拒绝攻击。 操作步骤1. 使能DHCP Snooping功能。 # 使能全局DHCP Snooping功能并配置设备仅处理DHCPv4报文。 system-viewHUAWEI sysname SwitchCSwitchC dhcp enableSwitchC dhcp snooping enable ipv4# 使能用户侧接口的DHCP Snooping功能。以GE0/0

4、/1接口为例，GE0/0/2的配置相同，此处省略。SwitchC interface gigabitethernet 0/0/1SwitchC-GigabitEthernet0/0/1 dhcp snooping enableSwitchC-GigabitEthernet0/0/1 quit2. 配置接口的信任状态：将连接DHCP Server的接口状态配置为“Trusted”。 3. SwitchC interface gigabitethernet 0/0/34. SwitchC-GigabitEthernet0/0/3 dhcp snooping trustedSwitchC-Gigab

5、itEthernet0/0/3 quit5. 使能ARP与DHCP Snooping的联动功能。 SwitchC arp dhcp-snooping-detect enable6. 使能根据DHCP Snooping绑定表生成接口的静态MAC表项功能。 # 在用户侧接口进行配置。以GE0/0/1接口为例，GE0/0/2的配置相同，此处省略。SwitchC interface gigabitethernet 0/0/1SwitchC-GigabitEthernet0/0/1 dhcp snooping sticky-macSwitchC-GigabitEthernet0/0/1 quit7. 使

6、能对DHCP报文进行绑定表匹配检查的功能。 # 在用户侧接口进行配置。以GE0/0/1接口为例，GE0/0/2的配置相同，此处省略。SwitchC interface gigabitethernet 0/0/1SwitchC-GigabitEthernet0/0/1 dhcp snooping check dhcp-request enableSwitchC-GigabitEthernet0/0/1 quit8. 配置DHCP报文上送DHCP报文处理单元的最大允许速率为90pps。 9. SwitchC dhcp snooping check dhcp-rate enableSwitchC d

7、hcp snooping check dhcp-rate 9010. 使能检测DHCP Request报文中GIADDR字段是否非零的功能。 # 在用户侧接口进行配置。以GE0/0/1接口为例，GE0/0/2的配置相同，此处省略。SwitchC interface gigabitethernet 0/0/1SwitchC-GigabitEthernet0/0/1 dhcp snooping check dhcp-giaddr enableSwitchC-GigabitEthernet0/0/1 quit11. 配置接口允许接入的最大用户数并使能对CHADDR字段检查功能。 # 在用户侧接口进行

8、配置。以GE0/0/1接口为例，GE0/0/2的配置相同，此处省略。SwitchC interface gigabitethernet 0/0/1SwitchC-GigabitEthernet0/0/1 dhcp snooping max-user-number 20SwitchC-GigabitEthernet0/0/1 dhcp snooping check dhcp-chaddr enableSwitchC-GigabitEthernet0/0/1 quit12. 配置丢弃报文告警和报文限速告警功能。 # 使能丢弃报文告警功能，并配置丢弃报文告警阈值。以GE0/0/1接口为例，GE0/0

9、/2的配置相同，此处省略。SwitchC interface gigabitethernet 0/0/1SwitchC-GigabitEthernet0/0/1 dhcp snooping alarm dhcp-chaddr enableSwitchC-GigabitEthernet0/0/1 dhcp snooping alarm dhcp-request enableSwitchC-GigabitEthernet0/0/1 dhcp snooping alarm dhcp-reply enableSwitchC-GigabitEthernet0/0/1 dhcp snooping alar

10、m dhcp-chaddr threshold 120SwitchC-GigabitEthernet0/0/1 dhcp snooping alarm dhcp-request threshold 120SwitchC-GigabitEthernet0/0/1 dhcp snooping alarm dhcp-reply threshold 120SwitchC-GigabitEthernet0/0/1 quit# 使能报文限速告警功能，并配置报文限速告警阈值。SwitchC dhcp snooping alarm dhcp-rate enableSwitchC dhcp snooping a

11、larm dhcp-rate threshold 50013. 验证配置结果 # 执行命令display dhcp snooping configuration查看DHCP Snooping的配置信息。SwitchC display dhcp snooping configuration# dhcp snooping enable ipv4 dhcp snooping check dhcp-rate enable dhcp snooping check dhcp-rate 90 dhcp snooping alarm dhcp-rate enable dhcp snooping alarm d

12、hcp-rate threshold 500 arp dhcp-snooping-detect enable # interface GigabitEthernet0/0/1 dhcp snooping enable dhcp snooping check dhcp-giaddr enable dhcp snooping check dhcp-request enable dhcp snooping alarm dhcp-request enable dhcp snooping alarm dhcp-request threshold 120 dhcp snooping check dhcp-

13、chaddr enable dhcp snooping alarm dhcp-chaddr enable dhcp snooping alarm dhcp-chaddr threshold 120 dhcp snooping alarm dhcp-reply enable dhcp snooping alarm dhcp-reply threshold 120 dhcp snooping max-user-number 20# interface GigabitEthernet0/0/2 dhcp snooping enable dhcp snooping check dhcp-giaddr

14、enable dhcp snooping check dhcp-request enable dhcp snooping alarm dhcp-request enable dhcp snooping alarm dhcp-request threshold 120 dhcp snooping check dhcp-chaddr enable dhcp snooping alarm dhcp-chaddr enable dhcp snooping alarm dhcp-chaddr threshold 120 dhcp snooping alarm dhcp-reply enable dhcp

15、 snooping alarm dhcp-reply threshold 120 dhcp snooping max-user-number 20# interface GigabitEthernet0/0/3 dhcp snooping trusted # # 执行命令display dhcp snooping interface查看接口下的DHCP Snooping运行信息。SwitchC display dhcp snooping interface gigabitethernet 0/0/1 DHCP snooping running information for interface

16、 GigabitEthernet0/0/1 : DHCP snooping : Enable Trusted interface : No Dhcp user max number : 20 Current dhcp and nd user number : 0 Check dhcp-giaddr : Enable Check dhcp-chaddr : Enable Alarm dhcp-chaddr : Enable Alarm dhcp-chaddr threshold : 120 Discarded dhcp packets for check chaddr : 0 Check dhc

17、p-request : Enable Alarm dhcp-request : Enable Alarm dhcp-request threshold : 120 Discarded dhcp packets for check request : 0 Check dhcp-rate : Disable (default) Alarm dhcp-rate : Disable (default) Alarm dhcp-rate threshold : 500 Discarded dhcp packets for rate limit : 0 Alarm dhcp-reply : Enable A

18、larm dhcp-reply threshold : 120 Discarded dhcp packets for check reply : 0 SwitchC display dhcp snooping interface gigabitethernet 0/0/3 DHCP snooping running information for interface GigabitEthernet0/0/3 : DHCP snooping : Disable (default) Trusted interface : Yes Dhcp user max number : 1024 (defau

19、lt) Current dhcp and nd user number : 0 Check dhcp-giaddr : Disable (default) Check dhcp-chaddr : Disable (default) Alarm dhcp-chaddr : Disable (default) Check dhcp-request : Disable (default) Alarm dhcp-request : Disable (default) Check dhcp-rate : Disable (default) Alarm dhcp-rate : Disable (defau

20、lt) Alarm dhcp-rate threshold : 500 Discarded dhcp packets for rate limit : 0 Alarm dhcp-reply : Disable (default) 配置文件# SwitchC的配置文件# sysname SwitchC# dhcp enable # dhcp snooping enable ipv4 dhcp snooping check dhcp-rate enable dhcp snooping check dhcp-rate 90 dhcp snooping alarm dhcp-rate enable d

21、hcp snooping alarm dhcp-rate threshold 500 arp dhcp-snooping-detect enable #interface GigabitEthernet0/0/1 dhcp snooping sticky-mac dhcp snooping enable dhcp snooping check dhcp-giaddr enable dhcp snooping check dhcp-request enable dhcp snooping alarm dhcp-request enable dhcp snooping alarm dhcp-req

22、uest threshold 120 dhcp snooping check dhcp-chaddr enable dhcp snooping alarm dhcp-chaddr enable dhcp snooping alarm dhcp-chaddr threshold 120 dhcp snooping alarm dhcp-reply enable dhcp snooping alarm dhcp-reply threshold 120 dhcp snooping max-user-number 20 #interface GigabitEthernet0/0/2 dhcp snoo

23、ping sticky-mac dhcp snooping enable dhcp snooping check dhcp-request enable dhcp snooping alarm dhcp-request enable dhcp snooping alarm dhcp-request threshold 120 dhcp snooping check dhcp-chaddr enable dhcp snooping alarm dhcp-chaddr enable dhcp snooping alarm dhcp-chaddr threshold 120 dhcp snooping alarm dhcp-reply enable dhcp snooping alarm dhcp-reply threshold 120 dhcp snooping max-user-number 20 #interface GigabitEthernet0/0/3 dhcp snooping trusted#return