It's your choice, but you don't really need a module for this. The simplest way might just be to match the first three numbers, then do a ">= and <=" on the range in the last one.

A slightly more elegant method exploits the fact that IPv4 address are actually 4 byte values -- notice each number ranges from 0-255 (an unsigned, one byte char). If you pack them in order you have a "big endian" (aka. network byte order) number, which is actually how low level networking uses them. Making this easy:

#!/usr/bin/perl -w
use strict;

sub dot2int {
    my $address = pop;
    my @bytes;
    while ($address =~ /(\d+)/g) {
        push @bytes,$1
    }
    return unpack('N',pack('C*',@bytes));
}

my $first = dot2int('192.168.1.120');
my $last = dot2int('192.168.1.141');

my @testcases = qw(
    192.168.1.130 
    193.168.1.122 
    255.0.0.27 
    192.168.1.127 
    192.168.1.144 
    192.168.1.139
);

print "$first to $last = ".
    ($last-$first)." addresses in range\n";

foreach (@testcases) {
    print $_;
    my $int = dot2int($_);
    if ($int >= $first && $int <= $last) {
        print " spammer!!!\n";
    } else { print " OK.\n" }
}
[download]

The output:

3232235896 to 3232235917 = 21 addresses in range
192.168.1.130 spammer!!!
193.168.1.122 OK.
255.0.0.27 OK.
192.168.1.127 spammer!!!
192.168.1.144 OK.
192.168.1.139 spammer!!!

I would assume there is a module somewhere that includes a function like that, but I can't tell you which one.