I think you'll need to change 
my $mask = "1" x ( 32 - $cidr ) . "0" x $cidr;

[download]
to 
my $mask = "1" x $cidr . "0" x ( 32 - $cidr );

[download]
since /8 means a mask of 255.0.0.0 and not 255.255.255.0 which is /24.
But thanks a lot for this example - I was wondering how do that without a module (and could not figure how bitwise shifting should help).

In reply to Re^3: behavior of bitwise shift by Golo
in thread behavior of bitwise shift by ngiordano

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