Cheats were a huge problem in the old version. It's fair to say that it killed Rust for a lot of people. We wrote some simple checks and banned a shitload of people, VAC banned a shitload of people, but we ended up spending more time writing anti-cheat and trying to trap cheats than actually developing the game. This is obviously not a feasible situation.
So we went about seeking a company to out-source this stuff to. In the newer version we opted to use
Easy Anti Cheat. We chose EAC because it's the less obtrusive solution we've found, the guys really love what they're doing, and the company is small enough to give a shit about us.
EAC has worked out good for us so far. They have done a lot of work for us, like making OSX and Linux versions of their client. We've had some short-term problems with their infrastructure dropping clients from servers but they've always been on hand to fix them.
It's naive to think that we can completely remove cheating from a PC game. The idea is to make it difficult and unattractive.