Deny DHCP Address by MAC?

[Adam Moffett]

An easy way would be to assign him an IP that doesn't work.



> A .EDU with insecure offices, network outlets, and labs, is trying to 
> track down a rogue DHCP client on their network that also happens to 
> be infected with conficker.
>
> They have a completely open DHCP setup (this is the entire dhcpd.conf 
> file):
>
> ddns-update-style ad-hoc;
> authoritative;
> subnet 192.168.9.0 netmask 255.255.255.0 {
>  range 192.168.9.125 192.168.9.200;
>   option subnet-mask 255.255.255.0;
>   option broadcast-address 192.168.9.255;
>   option routers 192.168.9.1;
>   option domain-name-servers 192.168.9.4;
>   option domain-name "xxx.xxx.xxx";
> }
>
> Any connected machine can get an address from the range specified in 
> the config file. Bouncing this one's lease merely results in it 
> getting a new one.
>
> They know the rogue machine's MAC address, of course.  Can they deny 
> it a DHCP address based only on the MAC? How? Thanks.