[bigboy81]

Is there any way to block /rcon exit command or leave it off?

[Lordzy]

Currently, no. The only way to block it is by creating a server sided RCON system.

[bigboy81]

can you give me some example of that system ?

[Lordzy]

Search for "server sided", you may get tutorials like server sided cash system and other. By using the same logic, you can create your own server sided RCON system. But make sure that you block default RCON login (Kick the player once if he/she logs in as RCON).

[Sime30]

Add this to your server.cfg

"rcon 0"

Without quotes