Stopping cheaters means that you'll always be one step behind them.
Just as Will said, I believe you can't stop people from being dishonnest. However, it is very possible to loop them out of the interesting gameplay as much as possible, by identifying all the cheats and block out the cheaters, time after time...

Spoil the "fun" of cheating, don't try to prevent it.

You have to play on the demotivation so the cheaters give up and don't try to chalenge them by saing it is impossible to cheat!