DoS attack on DHCP

[Joe Shen]

hi,

 we use DHCPd on our service network. 

 
 the structure looks like 

  dhcpd --- access_server --- customer

  access_server relay dhcp requests to dhcpd, and there are switches between  access_server and customers.

  from last week , we saw a lot of DHCP  requests from customer access networks, the ip address pool is exhausted  quickly while customers could not get IP address . But, the ip address pool should be enough as its size is calculated according to number of customers.

  Should anybody help with the following questions:

  1. is there any best pratice guide on DHCPd protection, esp. ip address exhausting attack?

  2. is there any way to forbid ip address lease to special MAC address ?

  3. is there any way to detect attacks early ? esp. is there any freeware available ? 


 each word will be highly appreciated.

Joe

  


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