So a few years back, before Wifi was really a major part of every business, the company I worked for decided to put in 2 WAP devices. Everyone in the office got really excited until it became apparent that this was for Managers and IT use only. This caused a bit of an uproar in the office as the users couldn't understand why they couldn't use the Wifi for their personal devices.
Almost about a week goes past and I arrive at work to a frantic phone call from one of the managers saying that half his team cant access the data server or print anything. Head down to their side of the office and see that the network connection shows as connected but not to our network. Ipconfig shows that they are receiving IP's but not from our network.
Immediately I start looking around and find exactly what I though it was. One of the staff had decided to by a cheap router and connect it to one of the open ports along the wall in order to get Wifi, but had never turned off the DHCP settings.
Removed the device (he tried stopping me by saying that its his and I cant touch it) and reported him and then had to give a mini seminar on Network and User security to the rest of the company.
Needless to say he didn't stay with the company for long....## TLDR Summary: