Please note that the RPM's and binaries here are compiled statically, i.e. require no external libraries to run. For that reason, they're quite large. The rpms and binaries with "-exec" here are compiled with the GAPING_SECURITY_HOLE option turned on and allow you to execute an arbitrary binary when someone connects to nc's listening port. This features is named GAPING_SECURITY_HOLE for a reason; DO NOT use this binary - heck, don't even download it - unless you are VERY confident you know what you're doing. If you simply want a stock netcat, please get it from your distribution; many include it.