Cool. I haven't had a look at NetAddr::IP but I had to some similar calculation in one of the NMS programs where we don't want to use non-core modules (in this case to determine if an IP was in a specified network.) In case one is in a similar position of needing to do this calculation and not able to install the module, the code can boil down to:

use Socket;

sub add_number_to_ip
{
   my ($ip,$number ) = @_;
   my $ip_i = ip_to_int($ip);
   $ip_i += $number;
   return inet_ntoa(pack('N', $ip_i));
}
                                                                      
+          

sub ip_to_int
{
   my ( $ip ) = @_;
   my $ip_n = inet_aton($ip);
   my $ip_i = unpack('N', $ip_n);
   return $ip_i
}
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/J\