Please i need help.

hello there
I'm hosting a cod4 obscurity server,and i did saw that some players use a bind to see the obs clearly and that isn't allowed and considering like a cheat,anyway lets call the bind obsbind so is there any way to prevent the players from using it? is that possible,Thanks in advance.

Thanks for the reply,but i have last version of cod4,not that the issue,i need better way or any script that prevent someone from use certain binds.