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->bits() 
print $block->size() 
print $block->maxblock()
print $block->broadcast()
print $block->next()

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.

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

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'.

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 muir@idiom.com.