how to determine and block IP address ranges?

i want to stop all comment spam from this ISP

[sivatag]

hi again,

my site's Wordpress blog has been hit by numerous spam comments originating from Ubiquityservers.com. From what i've seen discussed on other sites, Ubiquity appears to lack serious attention to stopping the spammers on their servers. i've implemented all of the blocks that Wizcrafts has suggested here and on his site. however, he does not block all of Ubiquityservers' IP addresses and today i'm still getting comment spam from them.

i'm not .htaccess savvy enough (yet-just starting on the tutorials here) to figure this out, so can someone help me on how to write a block for ALL IP addresses connected with this company? first, in general, how do you find out the entire range of IP addresses used by a company? then, how to write those lines of code to block them?

i would truly appreciate this as my blocks on individual and short ranges of IPs from Ubiquityservers are clearly not effective enough.

[jdMorgan]

Something like:

Order Deny,Allow
#
Deny from 173.234.0.0/16 174.34.128.0/18
#
<FilesMatch "^(robots\.txt|your-custom-403-error-document-filename-here\.html)$">
Allow from all
</FilesMatch>

Those guys have a ton of netblocks, and I only show two of them. You can research the rest of them
at arin.net ( [ws.arin.net...] ).

The two file exclusions prevent "looping" problems of two different kinds, and are important.

Jim