[rhn-users] what's best way to allow a part of ip range to access lan server ?

[FM]

our stations have their IP with DHCP (using MAC address).
192.168.x.50 -- 192.168.x.134


Other station (laptop from customer) received a ip from a range of :
192.168.x.135 -- 192.168.x.253

I'd like to disallow access from those stations to our lan server.

is host-allow the best way / easy way  ?

thanks !