There is some listing of my script I hope this example help you to understand some fundamental points in IP math.

#!/usr/local/bin/perl
# Written by Andrii Grytsenko 2010
# PP: http://andriigrytsenko.net    

use POSIX;

sub hex2bin {
   my $hex = shift;
   my $pack = unpack("B32",pack("N",$hex));
   my $pack = substr($pack,-8);
   return $pack;
}                                          

sub bin2hex {
   my $bin = shift;
   return unpack("N", pack("B32", substr("0" x 32 . $bin, -32)))
}                                                               

sub bin2ip {
    my $bin = shift;
    my $type = shift;
    my $ip;
    $ip .= bin2hex(substr($bin,0,8)) ."\.";
    $ip .= bin2hex(substr($bin,8,8)) ."\.";
    $ip .= bin2hex(substr($bin,16,8)) ."\.";
    if ( $type eq 'first') {
        $ip .= bin2hex(substr($bin,24,8)) + 1 ;
    } elsif ($type eq 'broad') {
        $ip .= bin2hex(substr($bin,24,8)) - 1 ;
    } else {
        $ip .= bin2hex(substr($bin,24,8));
    }
    return $ip;
}

sub normalization {
    my $line = shift;
    my ($ip,$mask) = split(/\//,$line);
    return($ip,$mask);
}

my ($ip,$net_mask) = normalization(@ARGV[0]);

my $host_mask = 32-$net_mask;
my $max_host = POSIX::pow(2,$host_mask)-2;
my $bin_mask = "1" x $net_mask . "0" x $host_mask;

my $bin_ip ;
$bin_ip .= hex2bin($_) foreach (split(/\./,$ip));

my $min = $bin_ip & $bin_mask;
my $max_mask = "0" x $net_mask . "1" x $host_mask;
my $max = $bin_ip  | $max_mask;

my $min_ip = bin2ip($min);
my $min_host_ip = bin2ip($min,'first');
my $max_ip = bin2ip($max);
my $max_host_ip = bin2ip($max,'broad');

print \<\< EOF
IP ADDRESS:\t $ip\t $bin_ip
NETWORK MASK:\t \/$net_mask\t\t $bin_mask
WILDCARD:\t \/$host_mask\t\t $max_mask
NETWORK IP:\t $min_ip\/$net_mask\t $min
BROADCAST ADDR:\t $max_ip\t $max
FIRST ADDR:\t $min_host_ip
LAST ADDR:\t $max_host_ip
MAX HOSTS\t $max_host
EOF

Run scripts with one argument ip/netmask… Unfortunately, you can use only short network mask type :

./ipcalc 192.157.9.3/21

the output looks like this:

IP ADDRESS:      192.157.9.3     11000000100111010000100100000011
NETWORK MASK:    /21             11111111111111111111100000000000
WILDCARD:        /11             00000000000000000000011111111111
NETWORK IP:      192.157.8.0/21  11000000100111010000100000000000
BROADCAST ADDR:  192.157.15.255  11000000100111010000111111111111
FIRST ADDR:      192.157.8.1
LAST ADDR:       192.157.15.254
MAX HOSTS        2046