Karl Ward > Net-MAC-1.2 > Net::MAC

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Module Version: 1.2   Source   Latest Release: Net-MAC-2.103622

NAME ^

Net::MAC - Perl extension for representing and manipulating MAC addresses

SYNOPSIS ^

  use Net::MAC;
  my $mac = Net::MAC->new('mac' => '08:20:00:AB:CD:EF'); 

  # Example: convert to a different MAC address format (dotted-decimal)
  my $dec_mac = $mac->convert(
          'base' => 10,         # convert from base 16 to base 10
          'bit_group' => 8,     # octet grouping
          'delimiter' => '.'    # dot-delimited
  ); 

  print "$dec_mac\n"; # Should print 8.32.0.171.205.239

  # Example: find out whether a MAC is base 16 or base 10
  my $base = $mac->get_base();
  if ($base == 16) { 
          print "$mac is in hexadecimal format\n"; 
  } 
  elsif ($base == 10) { 
          print "$mac is in decimal format\n"; 
  }
  else { die "This MAC is neither base 10 nor base 16"; } 

DESCRIPTION ^

This is a module that allows you to

  - store a MAC address in a Perl object
  - find out information about a stored MAC address
  - convert a MAC address into a specified format
  - easily compare two MAC addresses for string or numeric equality

There are quite a few different ways that MAC addresses may be represented in textual form. The most common is arguably colon-delimited octets in hexadecimal form. When working with Cisco devices, however, you are more likely to encounter addresses that are dot-delimited 16-bit groups in hexadecimal form. In the Windows world, addresses are usually dash-delimited octets in hexadecimal form. MAC addresses in a Sun ethers file are usually non-zero-padded, colon-delimited hexadecimal octets. And sometimes, you come across dot-delimited octets in decimal form (certain Cisco SNMP MIBS actually use this). Hence the need for a common way to represent and manipulate MAC addresses in Perl.

There is a surprising amount of complexity involved in converting MAC addresses between types. This module does not attempt to understand all possible ways of representing a MAC address in a string, though most of the common ways of representing MAC addresses are supported.

METHODS ^

new() method (constructor)

The new() method creates a new Net::MAC object. Possible arguments are

  mac           a string representing a MAC address
  base          a number corresponding to the numeric base of the MAC 
                possible values: 10 16
  delimiter     the delimiter in the MAC address string from above 
                possible values: : - . space
  bit_group     the number of bits between each delimiter 
                possible values: 8 16 48
  zero_padded   whether bit groups have leading zero characters
                (Net::MAC only allows zero-padding for bit groups of 8 bits)
                possible values: 0 1 
  verbose       write informational messages (useful for debugging)
                possible values: 0 1
  die           die() on invalid MAC address (default is to die on invalid MAC) 
                possible values: 0 1 (default is 1)

When the new() method is called with a 'mac' argument and nothing else, the object will attempt to auto-discover metadata like bit grouping, number base, delimiter, etc. If the MAC is in an invalid or unknown format, the object will call the croak() function. If you don't want the object to croak(), you can give the new() method a die argument, such as:

  my $m_obj = Net::MAC->new('mac' => '000adf012345', 'die' => 0); 

There are cases where the auto-discovery will not be able to guess the numeric base of a MAC. If this happens, try giving the new() method a hint, like so:

  # Example: this MAC is actually in decimal-dotted notation, not hex
  my $mac = Net::MAC->new('mac' => '10.0.0.12.14.8', 'base' => 10); 

This is necessary for cases like the one above, where the class has no way of knowing that an address is decimal instead of hexadecimal.

accessor methods

get_mac() method

Returns the MAC address stored in the object.

get_base() method

Returns the numeric base of the MAC address. There are two possible return values:

  16    hexadecimal (common)
  10    decimal (uncommon)

get_delimiter() method

Returns the delimiter, if any, in the specified MAC address. A valid delimiter matches the following regular expression:

  /\:|\-|\.|\s/

In other words, either a colon, a dash, a dot, or a space. If there is no delimiter, this method will return the undefined value (undef). If an invalid delimiter is found (like an asterisk or something), the object will call the croak() function.

get_bit_group() method

Returns the number of bits between the delimiters. A MAC address is a 48 bit address, usually delimited into 8 bit groupings (called octets), i.e.

  08:20:00:AB:CD:EF

Sometimes, MAC addresses are specified with fewer than 5 delimiters, or even no delimiters at all:

  0820.00ab.cdef        # get_bit_group() returns 16
  082000abcdef          # get_bit_group() returns 48, no delimiters at all

get_zero_padded() method

Returns a boolean value indicating whether or not the bit groups are zero-padded. A return value of 0 (false) means that the bit groups are not zero-padded, and a return value of 1 (true) means that they are zero-padded:

  00.80.02.ac.4f.ff     # get_zero_padded() returns 1
  0:80:2:ac:4f:ff       # get zero_padded() returns 0
  0.125.85.122.155.64   # get_zero_padded() returns 0 

Net::MAC only allows bit groups of 8 bits to be zero-padded.

convert() method

Convert an already-defined Net::MAC object into a different MAC address format. With this function you can change the delimiter, the bit grouping, or the numeric base.

  # Example: convert to a different MAC address format (dotted-decimal)
  my $new_mac_obj = $existing_mac_obj->convert(
          'base' => 16,         # convert to base 16, if necessary
          'bit_group' => 16,    # 16 bit grouping
          'delimiter' => '.'    # dot-delimited
  );

Conversion to common formats

The most common formats have shortcut conversion methods that can be used instead of the convert() method with its many options.

as_Cisco() method

Cisco routers seem to usually represent MAC addresses in hexadecimal, dot-delimited, 16 bit groups.

  my $mac = Net::MAC->new(mac => '00-02-03-AA-AB-FF'); 
  my $cisco_mac = $mac->as_Cisco(); 
  print "$cisco_mac"; 
  # should print 0002.03aa.abff

as_IEEE() method

The IEEE 802 2001 specification represents MAC addresses in hexadecimal, colon-delimited, upper case, 8 bit groups.

  my $mac = Net::MAC->new(mac => '00-02-03-AA-AB-FF'); 
  my $IEEE_mac = Net::MAC->as_IEEE(); 
  print "$IEEE_mac"; 
  # should print 00:02:03:AA:AB:FF

as_Microsoft() method

Microsoft usually represents MAC addresses in hexadecimal, dash delimited, upper case, 8 bit groups.

  my $mac = Net::MAC->new(mac => '00:02:03:AA:AB:FF'); 
  my $microsoft_mac = $mac->as_Microsoft(); 
  print "$microsoft_mac"; 
  # should print 00-02-03-AA-AB-FF

as_Sun() method

Sun represents MAC addresses in hexadecimal, colon-delimited, non-zero-padded, lower case, 8 bit groups.

  my $mac = Net::MAC->new(mac => '00-02-03-AA-AB-FF'); 
  my $sun_mac = $mac->as_Sun(); 
  print "$sun_mac"; 
  # should print 0:2:3:aa:ab:ff

Stringification

The stringification operator "" has been overloaded to allow for the meaningful use of the instance variable in a string.

  my $mac = Net::MAC->new(mac => '00:0a:23:4f:ff:ef'); 
  print "object created for MAC address $mac"; 
  # Should print:
  # object created for MAC address 00:0a:23:4f:ff:ef

MAC address comparison

The Perl operators 'eq' and 'ne' (string comparison) and '==' '!=' (numeric comparison) have been overloaded to allow simple, meaningful comparisons of two MAC addresses.

Example (two MAC addresses numerically identical but in different formats):

  my $d = Net::MAC->new(mac => '0.8.1.9.16.16', base => 10); 
  my $h = Net::MAC->new(mac => '00:08:01:0A:10:10', base => 16); 
  if ($d == $h) { print "$d and $h are numerically equal"; } 
  if ($d ne $h) { print " but $d and $h are not the same string"; } 

BUGS ^

Malformed MAC addresses

Net::MAC can't handle MAC addresses where whole leading zero octets are omitted. Example:

  7.122.32.41.5 (should be 0.7.122.32.41.5)

Arguably, that's their problem and not mine, but maybe someday I'll get around to supporting that case as well.

Case is not preserved

Net::MAC doesn't reliably preserve case in a MAC address. I might add a flag to the new() and convert() methods to do this. I might not.

Zero-padding is not configurable

Net::MAC doesn't allow you to specify whether or not bit groups should be zero-padded. It always writes out base 16 addresses as zero-padded. Example:

  You supply '8.32.0.171.205.239' and you want '8:20:0:ab:cd:ef'.  
  Net::MAC gives you '08:20:00:ab:cd:ef' and a kick in the face. 

Support for configurable zero-padding is forthcoming.

SEE ALSO ^

Net::MacMap Net::MAC::Vendor

AUTHOR ^

Karl Ward <karlward@cpan.org>

CONTRIBUTORS ^

Oliver Gorwits, Robin Crook

COPYRIGHT AND LICENSE ^

Copyright (C) 2005-2007 Karl Ward <karlward@cpan.org>

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

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