I'm not after any institution's security secrets, just a 'you might want to look at...' sort of answer. Our resident 'power user' amongst the staff recently plugged in a machine of his own onto the network here and caused multiple duplicate IP warnings all over the place. This has lead to a senior bod querying the 'security' of our network vis a vis 'rogue devices'. So, how do other places deal with this particular nugget? Managed switches tied to MAC addresses? Encrypting all network traffic? Is there a 'keep the senior bod happy' box I could buy and plug into the network? Any advice very gratefully received, as usual.