How exactly do they catch you?

Oh dear...

Any measures I can take to guard myself from getting IP banned? I don't have the money to afford a VPN right now (and I wouldn't buy it JUST for the sake of ban-shield anyway).

If you do,its proxy time.

Sorry, I don't follow.

well ..
this thread again , lets give it the good old college try!

GM items
random waves
public hacking

Ah,well you do get IP banned theres always a proxy,which masks your IP with a different one in a different place.

Best short desc I could come up with.

they tap you on your shoulders and say "tag, you're it!"

They only ban dynamic IP? I thought they would ban your static IP. Banning dynamic seems pointless since you can just change that yourself without the need for a proxy.

My apologies. I guess I should have gave the ol' search button a try first.

Being the awesome expert on network issues (SHUT UP I AM!) if you have a dynamic or static IP depends on your provider, and most give out dynamic ones. Basically, they are muttually exclusive: you either have a static one or a dynamic one, and Nexon probably can`t/won`t worry about looking which one you got.

Or I could be terribly mistaken (NO IM NOT!).

This post is very right. Stealing cash shop items is equal to shoplifting in a store. Since it cost's real money to obtain these items. Hacking for these items may not only result in a permanent IP ban, it could also result in a jail sentence.

Edit:They don't give a shit if you hack in any other way. As long as it doesn't effect their profits(Which public hacking does sometimes) you will not get banned. Hell, you could invite Nexon over to your house and say "Look at these sexy hacks", and they would say "Cool".

Even CS items don't really seem to count, tbh.
They might remove some obvious things like 1000 AP caps, but they don't ban for that.

They ban for GM gear though.