use Socket;
my $mask = 24; # 255.255.255.0 -> 24 bit netmask
my $network = inet_aton("192.168.20.0");

my @myips;

foreach $ip ( @iplist ) {
    $ip = inet_ntoa($ip); # convert ascii to decimal
     if( ($ip & $mask) == ($network & $mask) ){
        push @myips, $ip;
    }
}
# this will sort the list properly since it's sorting the numbers.
# otherwise it would sort 192.168.20.20 before 196.168.20.3
@myips = sort @myips;
foreach $ip ( @myips ) {
    # print out the ascii format
    print inet_ntoa($ip), "\n";
}