use constant REGEXP_IPADDR   => qr!^((?:(?:25[0-5]|2[0-4]\d|[0-1]??\d{1,2})[.](?:25[0-5]|2[0-4]\d|[0-1]??\d{1,2})[.](?:25[0-5]|2[0-4]\d|[0-1]??\d{1,2})[.](?:25[0-5]|2[0-4]\d|[0-1]??\d{1,2})))$!;
sub valid_ipaddr
{
   my $value = shift;
   return $value =~ REGEXP_IPADDR;
}