Around 1998 I snagged an abandoned 486 and installed Linux on it for use at work; the corporate software I used the most, a ticketing system, could be run using X from a Solaris server. I don't remember what I did for Lotus Notes.

Anyway, the IT department spotted it but since I was using SMB it thought it was just another Windows server. No one ever checked up on it despite being plugged into the corporate network.

This was a Fortune 500 company; things have changed a wee bit since then.