[lug] Decoding partial IP addresses

[Vince Dean]

I'm looking at a .htaccess file (the per-directory access control
file for Apache) and seeing entries like the following:

   allow from 195.83.22.
   allow from 128.100.80.

I would like to know which organizations are being given access here.

I'm taking over management of a system and there are lots
of configuration details like these to figure out.

I understand that these entries describe the 24-bit prefix of the
allowed IP addresses, which should identify the subnet in
question, and could presumably be associated with a specific
organization.

I know how to use host or nslookup to decode a complete IP address,
but I don't know what to do with a partial address.

I was actually able to answer my question quickly by running
host on some arbitrary addresses within the subnet:

   host xx.xx.xx.1
   host xx.xx.xx.2
   etc.

but I would like to know if there is a more general way to find out who
owns (if that's the right word) a particular part of the IP
address space.  More for my general understanding than to solve an
immediate problem.

Any suggestions?

Thanks,
Vince