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三种针对DHCP的攻击:
1.DHCP饿死攻击
2.仿冒DHCP Server 攻击
3.DHCP中间人攻击
DHCP 饿死攻击
原理:攻击者持续改变DHCP报文中的chaddr字段,持续的向DHCP服务器申请大量的IP的地址,导致用户不能正常分配
漏洞分析:DHCP服务器分配地址时无法分辨正常的申请者和恶意的申请者
仿冒DHCP攻击
原理:攻击者仿冒dhcp服务器给客户端分配错误的网关地址和ip等参数,导致正常的用户无法上网
漏洞分析:dhcp客户端接收dhcp分配的信息时,无法分配正确的dhcp服务器信息和仿冒的dhcp服务器信息
DHCP中间人攻击
原理:攻击者例用arp机制,让客户端学习到中间人的mac地址和服务器IP的对应关系,又让dhcp服务器学习到客户端ip和中间人mac的对应关系
如此一来,客户端与服务器的交互报文都会经过中间人中转
漏洞分析:从本质上讲,中间人攻击是一种spoofing ip/mac攻击,中间人利用虚假的ip地址与mac地址之间的映射关系来同时欺骗dhcp服务器和客户端。
DHCP snooping
饿死攻击: 对DHCP request报文进行源mac地址和chaddr字段检查,发现不一致,丢弃此报文
[sw1]dhcp snooping enable
[sw1]interface GigabitEthernet 0/0/1
[sw1-GigabitEthernet0/0/1]dhcp snooping check dhcp-chaddr enable
仿冒dhcp攻击:添加信任端口,默认所有端口都是untrust ,设置trust端口连接服务器,认为通过的offer/ACK报文是合法的
[SW]dhcp enable
[SW]dhcp snooping enable
[SW]int g0/0/2
[SW-GigabitEthernet0/0/2]dhcp snooping trusted
DHCP中间人攻击:用snooping形成交换机ip和mac地址绑定表,报文进入交换机和绑定表对比,不匹配discard
[SW]dhcp enable
[SW]dhcp snooping enable
[SW-GigabitEthernet0/0/2]ip source check user-bind enable
配置环境:华为S5700交换机