Whatmask v 1.0
==============

By: Joe Laffey <joe@laffeycomputer.com>
Updates: http://www.laffeycomputer.com/software.html


Whatmask is a small C program that lets you easily convert between three
common subnet mask notations. 

Notations supported:

 Name                  Example
---------------------------------
 CIDR                         /24
 Netmask            255.255.255.0
 Wilcard Bits           0.0.0.255


The above notations are all identical. CIDR notation commonly has a "/" in
front of the number (representing the number of bits). Whatmask can accept
these notations with or without a slash. This notation is used more and more
recently. A lot of popular routers and software supprt this notation.

Netmask notation is pretty much the standard old-school way of doing it. It 
is supported by most systems (Un*x, Win, Mac, etc.).

Wilcard bits are similar to the netmask, but they are the logical not of the
netmask. This notation is used by a number of popular routers (and nobody
knows why...).

To use Whatmask simply type "whatmask <notation>" The notation can be in any
of the three formats and Whatmask will automagically figure out what it is
and display all three notations.

To find out more about subnets and netmasks see the References section below.


Examples
========

myhost> whatmask /26

---------------------------------------------
       TCP/IP SUBNET MASK EQUIVALENTS
---------------------------------------------
CIDR = .....................: /26
Netmask = ..................: 255.255.255.192
Cisco Wildcard Bits = ......: 0.0.0.63


myhost> whatmask 255.255.192.0

---------------------------------------------
       TCP/IP SUBNET MASK EQUIVALENTS
---------------------------------------------
CIDR = .....................: /18
Netmask = ..................: 255.255.192.0
Cisco Wildcard Bits = ......: 0.0.63.255


myhost> whatmask 0.0.0.31

---------------------------------------------
       TCP/IP SUBNET MASK EQUIVALENTS
---------------------------------------------
CIDR = .....................: /27
Netmask = ..................: 255.255.255.224
Cisco Wildcard Bits = ......: 0.0.0.31



References
==========

O'Reilly and Assocaites:
TCP/IP Network Administration, 2nd Edition
By Craig Hunt
2nd Edition December 1997
1-56592-322-7
http://www.ora.com/

Cisco - IP Addressing and Subnetting for New Users
http://www.cisco.com/warp/public/701/3.html

More info on Wilcard bits and Cisco routers.
http://www.delmar.edu/Courses/ITSC1391/Sem3/6ACLs.htm

Then of course you can do a net search... I like http://www.google.com/


That's all, folks!
