Some 14 months go by and I do a Super Search...

How about this?

# converts decimal dotted quad string to network ordered long
sub dottedquad2long {
  return unpack('N', inet_aton(shift));
#  or
#  return unpack 'N', pack 'C4', split /\./, shift;
#  or
#  my @seg = split(/\./, shift);
#  return $seg[0]*256**3+$seg[1]*256**2+$seg[2]*256+$seg[3];
}
[download]

Shamelessly stolen from IP Manipulation: An Exercise

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Cheers, Joe