I don't know if this is already around, if I has i'm sorry for wasting time... I've not seen it though.
This is basically a module which bans certain GECOS's from the network. You can add and remove them. Like a spam filter, but this would not allow the user to connect at all.
For example...
On my network my GECOS would be "Network Owner". I wouldn't want someone else coming in using that one, so therefore I could be put into an exempt list so it would allow me to connect. If someone else came on with that it would tell them to change the GECOS and try again.
If you don't understand fully what I mean then let me know and I'll try and rephrase it... I know what i'm trying to say.