$net_m{'net_01'} = '192.168.10.0';

$src = '192.168.10.1';
$i = 'net_01';

printf  "Network to test: $net_m{$i}" . "\n" ;

printf  "Address to test: $src\n" ;
$a=$src;
$b=$net_m{$i};

$a=~ s/(\d+).(\d+).(\d+).(\d+)/$ 1 .$ 2 .$ 3 /;
$b=~ s/(\d+).(\d+).(\d+).(\d+)/$ 1 .$ 2 .$ 3 /;
printf  "Result \$a: $a\n" ;
printf  "Result \$b: $b\n" ;

if ($a=~ s/(\d+).(\d+).(\d+).(\d+)/$ 1 .$ 2 .$ 3 / eq $b=~ s/(\d+).(\d+).(\d+).(\d+)/$ 1 .$ 2 .$ 3 /) 
{ 
  printf  "получилась" 
}