Hello Mr. Busschots. Exucuse me for my english. I'm Italian student. I doing as tell you, but don't work. You to be able to send me the plugin check_rogue_detect.pl and DHCPDetect.pm and OUI.pm and tell me where i must modify them, going to put my ip address and mac address in type file (in either file up mention), that is check_rogue_detect.pl, DHCPDetect.pm and OUI.pm. i use eth1 and not eth0; my address is 143.225.x.x and my mac address is 00:08:a1:x:x:x All that, i need because i doing a degree thesis on Nagios and i have to make really that thing (object). I hope thah You help me. thank's a lot. Meanwhile of a His neighbourly reply, i hope at You a have a nice day. PS: my name is Oswald (Osvaldo)