Thank to Verna Avril and that suzan von otter for finding a bug that causes Local accounts to be banned even though they are not on the list, if the list contained spaces or a null line with just a carriage return line feed. Version 12 is released in their honor and contains this new function. Special thanks to princeofAmor for suggesting to ignore npc's. That cuts out 5 additional operations per iteration making the device faster if you have npc's on your land. :)

NEW VERSION 12. By popular request, it now also tells the person as well as the owner why a person was banned. Also flying is ON by default.
Presenting the OVERWATCH SENTRY. What does it do? Well, you can enter a list of grids to ban, people to ban by name, ip, or key. It also monitors each person that comes into your sim, and if they are wearing too many scripts to try and crash your sim, it bans them. If they are using too much sim memory and eating up all system resources, it bans them. If they are flying and you turn off flying in the system, it bans them. If they are too tall or too short, it bans them. So it does a lot, and it's all settable by you. I didn't do ban by age because avatar age is unreliable and can return a 0 day age. Not to mention that we all sometimes have to start over. The device is by the christmas tree at cyberdatastorm.com:8002/wizardry. It's a different kind of device from a security system. Security systems ban everyone except those you allow in. This lets everybody in - but it checks them to make sure they are not hacking or trying to hurt your sim, but it can also ban people from a list. It's really simple to use, just add the name to the appropriate list in the objects inventory, then just click to turn it on. Only the owner can turn it on or off.