NAME

NAME
Net::Netmask - parse, manipulate and lookup IP network blocks

SYNOPSIS
use Net::Netmask;

$block = new Net::Netmask (network block)
$block = new Net::Netmask (network block, netmask)

print $block->base()
print $block->mask()
print $block->hostmask()
print $block->bits()
print $block->size()
print $block->maxblock()
print $block->broadcast()
print $block->next()
print $block->match($ip);
print $block->nth(1);

for $ip ($block->enumerate()) { }

for $zone ($block->inaddr()) { }

my $table = {};
$block->storeNetblock()
$block->storeNetblock($table)

$block = findNetblock(ip)
$block = findNetblock(ip, $table)

DESCRIPTION
Net::Netblock parses and understand IPv4 CIDR blocks. It's built with an
object-oriented interface. Nearly all functions are methods that operate
on a Net::Netblock object.

There are methods that provide the nearly all bits of information about
a network block that you might want.

CONSTRUCTING
Net::Netmask objects are created with an IP address and optionally a
mask. There are many forms that are recognized:

'140.174.82.0/24' The preferred form.

'140.174.82.0:255.255.255.0'
'140.174.82.0', '255.255.255.0'
'140.174.82.0', '0xffffff00'
'140.174.82.4' A /32 block.

'140.174.82' Always a /24 block.

'140.174' Always a /16 block.

'140' Always a /8 block.

'140.174.82/24'
'140.174/16'
'default' 0.0.0.0/0 (the default route)

METHODS
base() Returns base address of the network block as a
string. Eg: 140.174.82.0. Base does not give an
indication of the size of the network block.

mask() Returns the netmask as a string. Eg: 255.255.255.0.

hostmask() Returns the host mask which is the oposite of the
netmask. Eg: 0.0.0.255.

bits() Returns the netmask as a number of bits in the
network portion of the address for this block.
Eg: 24.

size() Returns the number of IP addresses in a block. Eg:
256.

broadcast() The blocks broadcast address. (The last IP address
inside the block.) Eg: 192.168.1.0/24 =>
192.168.1.255

next() The first IP address following the block. (The IP
address following the broadcase address.) Eg:
192.168.1.0/24 => 192.168.2.0

match($ip) Returns TRUE if the IP number $ip matches the given
network. That is, TRUE is returned if $ip is
between base() amd broadcast(). For example, if
we have the network 192.168.1.0/24, then

192.168.0.255 => FALSE
192.168.1.0 => TRUE
192.168.1.1 => TRUE
...
192.168.1.255 => TRUE

$ip should be a dotted-quad (eg:
"192.168.66.3")

maxblock() Much of the time, it is not possible to determine
the size of a network block just from it's base
address. For example, with the network block
'140.174.82.0/27', if you only had the
'140.174.82.0' portion you wouldn't be able to
tell for certain the size of the block.
'140.174.82.0' could be anything from a '/23'
to a '/32'. The maxblock() method gives the
size of the larges block that the current
block's address would allow it to be. The size
is given in bits. Eg: 23.

enumerate() Returns a list of all the IP addresses in the
block. Be very careful not to use this function
of large blocks. The IP addresses are returned
as strings. Eg: '140.174.82.0', '140.174.82.1',
... '140.174.82.255'.

nth($index) Returns the nth element of the array that enumerate
would return if it were called. So, to get the
first usable address in a block, use nth(1). To
get the broadcast address, use nth(-1). To get
the last usable adress, use nth(-2).

inaddr() Returns an inline list of tuples. There is a tuple
for each DNS zone name in the block. If the
block is smaller than a /24, then the zone of
the enclosing /24 is returned.

Each tuple contains: the DNS zone name, the
last component of the first IP address in the
block in that zone, the last component of the
last IP address in the block in that zone.

Examples: the list returned for the block
'140.174.82.0/23' would be: '82.174.140.in-
addr.arpa', 0, 255, '83.174.140.in-addr.arpa',
0, 255. The list returned for the block
'140.174.82.64/27' would be: '82.174.140.in-
addr.arpa', 64, 95.

storeNetblock([$t]) Adds the current block to an table of network
blocks. The table can be used to query which
network block a given IP address is in.

The optional argument allows there to be more
than one table. By default, an internal table
is used. If more than one table is needed, then
supply a reference to a HASH to store the data
in.

FUNCTIONS
findNetblock(ip, [$t]) Search the table of network blocks (created with
storeNetBlock) to find if any of them contain
the given IP address. The IP address is
expected to be a string.

The return value is either a Net::Netblock
object or undef.

COPYRIGHT
Copyright (C) 1998, David Muir Sharnoff. All rights reserved. License
hearby granted for anyone to use this module at their own risk. Please
feed useful changes back to [email protected].