At first I thought something like Net::IP or NetAddr::IP could handle this, but apparently they don't. I would just write some regexps to pull this apart.

The following is pretty fragile in that it will fail to deal with bogus data like 10.11.12.30-29, but that should be easy enough to trap.

use strict;
use warnings;

while (<>) {
    chomp;
    s/\s*#.*$//;

    if (my ($stem, $first, $last) = /\b(\d+(?:\.\d+){2})\.(\d+)-(\d+)\
+b/) {
        print "$stem.$_\n" for $first..$last;
    }
    elsif (/\b(\d+(?:\.\d+){3})\b/) {
        print "$1\n";
    }
}
[download]

update: gah. I didn't initially spot that other octets apart from the last octet might have ranges in them. That means this solution is too simple-minded to be of much use.