The secret is to use a sort function. Er, my mistake, you're using one already ... you just need to do a few more comparisons. Perl doesn't have a built in octet comparator for some reason. I use the following little guy a lot, so I just cut and pasted it here. It may help. I call it my ipsort_pipet.

my @lines = <STDIN>;
print $_ for sort cmp_ip @lines;

sub cmp_ip {
    my @c = split /\./, $a;
    my @d = split /\./, $b;

    for(0.. 3) {
        return $c[$_] <=> $d[$_] if $c[$_] != $d[$_]
    }

    return $a cmp $b
}
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