For as long as I can remember I've been frustrated by the clunky interfaces
of IP subnet calculators available. Many years ago I wrote my own calculator
in Visual Basic and was happy with it until CIDR came into wide use... my tool
didn't support it and my code was too messy to fix. I wrote a quick tool
in Perl that I've used for many years since, but my co-workers always
laugh at my command-line calculator so I decided to give it a GUI front end
using Tk. Although I had to curse at the Tk
pack() geometry manager quite a bit I've finally gotten an interface that is
simple to use and understand.
Screenshot (click to enlarge):
If you're new to IP addressing in general and subnet masking in particular
the IP Address Abacus can help your understanding (I've taught several classes
with it.) Here are the standards for such things, Google can point you to many
web sites giving explanations and examples.
- RFC 950 Internet Standard Subnetting Procedure
- RFC 4632 Classless Inter-Domain Routing (CIDR)
- RFC 1219 The Assignment of Subnet Numbers
- RFC 1812 Requirements for IP Version 4 Routers
- RFC 1918 Address Allocation for Private Internets
- IP Address Abacus v1.3 (1.2MB) - for Win32 systems.
- Source Code - for everyone else.
- I use ActivePerl for my Win32 Perl work, plus ActiveState's Perl Dev Kit to make my executables... and yes I still use Notepad as my editor-of-choice.