Stopping Hackers

[NateDog]

We're having an issue with people crashing our server and they seem to be
getting a kick out of it.  I've done this recent patch on the server I found
made by the guy that created autokick and you patch one of the linux
binaries to keep people from spawning crap onto the map to crash it.  That
slowed peeps down a little.  But I think peeps are crashing it by sending
some kind of commands to the server.  Is it possible to disable that?  Maybe
disable all remote commands unless they have rcon access or don't allow any
commands but rcon commands?  That might not be possible but I thought I'd
ask.  And yes we have mods to keep peeps from doing ladder and nade crashes
but they're doing it another way I think.  Any help appreciated.

Thanks,
  NateDog