Worked in a company where 2 guys in IT set the whole system up. Even weird custom protocol for the network. Even consultants fetched in couldn't decipher or even gain access. The two guys barricaded themselves behind a steel door in a vault. Only way to communicate with them was a ticket system. Nobody else had the codes to get into their dungeon (servers were in there as well). They were well paid ... Only once hot one of them to come out. Contractor had (without my permission) plugged a USB stick in and virus warning went off. I had to run to said steel door and jump up and down in front of the camera until they asked me through intercom why I'm there. Was fun.