The main goal of IT is to provide security to the company network. You must accomplish this by any means necessary. If it means stopping every one else from doing their job, so be it. Stop them. Most of these dim wits who think they are working, always create problems for IT. For IT to be efficient they have to be stopped. So stop them.
Once you have established the rule, "IT rules", most people will cower before you and try to get their work done without offending you or getting on the wrong side of you. That means you can celebrate "Mission Accomplished". Your company will have a few that know how networks work and know a smattering of knowledge about Unix or Linux. They might have even served as root of some lab or the other in the grad school. Find them, stop them completely on their tracks. Thwart every one of their moves. Either they leave you alone, or the leave the company. I T should have unquestioned authority over the corporate infrastructure, and ideally there should be no one in the company capable of questioning you.
So the rules for IT is "IT Rules".