Just a thought, We created something like what I am going to explain for our gamming server, and pretty sure it can be done with phpBB, but we dont know the workings of phpBB very well. Well here it goes...
What I was thinking was a way to create a ban bypass system. Basically if you ban a range ban to stop a hacker, or just a problemmatic person, then you ban everyone in that guys range. I know, since we are a gamming clan and we have some people we have banned from our server but not our forums for reason's that it would ban a few other people that dont deserver to be banned.
Basically what we did was we created a way, if we ban a range and someone that doesent deserver to be banned is cought up in the ban, we give them there own private password, and when they com on, they type the password we gave them and it will bypass the ban. Only as long as they use that password they can bypass the ban. If they forget it or loose it then they have to contact the admin to reset there password or retrieve it. The was our log works on our gamming server is like if its a range ban of 184.108.40.206 - 220.127.116.11 we would type something like
18.104.22.168-22.214.171.124|PASSWORD|REASON FOR BANNING
But would have to be that eloberate, just a way so we can ban ranges but people that are cought up in that range can be givin a password to bypass it, and also create the password section in the ban section, either right on that page or make like a little icon that would be hiddin on that page where they would click that certian image and that would popup a password selection, either on a new page or right on that page.
Didnt know if its possiable with phpBB to do something like that.