using underscore allows you to wildcard a single character place
I'm not following... do you mean "192.168.1.16_" and that would match .160 --> .169 ?
I guess that would cut down on some of the entries, but say you had a /28 subnet you wanted to block.
If you could just enter 188.8.131.52/28 instead of:
That would, to me, make much more sense. Plus you know the IP's should be treated as a group, not single entries.
If CIDR notation is an issue, then maybe: