Ok, I really need some help with this one. I'm not necessarily the most versed person when it comes to network security, and this baffles me to no end.\n\nI have four clients showing up on the router's DHCP list. I recognize three of them as my Windows machines - this is normal. However, the fourth one is unfamiliar to me and apparently it uses Mac OSX. Definitely nothing in my house uses OSX.\n\nThe router has wireless disabled.\n\nI checked Cisco Network Magic's network history, and this "Mac" shows up as having connected very briefly last Friday at around 3 pm, then Monday at about 2 pm, and again a little after 6 pm. Again on Tuesday morning at around 8:30 am. Thursday morning a little after 6 am. These are very brief connections and do not linger on. The reason I listed these times is to show how random they are.\n\nWhat possible reasons could there be for this?\n\nIf someone was tapping into my cable, would they show up as DHCP clients even though they're not physically (or wirelessly for that matter) connected to my router?\n\nIf I had a backdoor trojan on my PC, could that be used to take out a DHCP lease? Basically what I am asking is, what does it require for an entity to acquire a DHCP lease from an Ethernet router?