Different subnet calculator wanted

[Valnar]

I'm looking for a subnet calculator (app, web based or whatever) that can easily list the subnets required to encompass a given range. I haven't found one that does it automatically.

For example:
Let's say I want to block the range 1.61.176.0 - 1.61.255.255 on my firewall.

It breaks down to
1.61.176.0/20 (1.61.176.1 - 1.61.191.254)
1.61.192.0/18 (1.61.192.1 - 1.61.255.254)

Figuring out I need two subnets, a /20 and /18, is fairly easy to obtain with a subnet calculator and a few seconds of trial-&-error, but it would be nice if there was a calculator that did it for me. This way I could delegate the task to someone else who is not as familiar with subnetting. Does such an animal exist?

This would also be neat: Imagine you are defining phase 2 of a VPN and want to include all 192.168.0.0/16 addresses EXCEPT for a couple /24's. The same calculator could list out all the subnets that wrap around and exclude those few, since a /16 would no longer work.

I'm surprised nobody has thought of this yet, or my google skills are failing today.

 

[Azuroth]

Valnar,

I don't know if it will be able to do what your looking for, but when I had to do subnetting while in school for projects. I used http://www.vlsm-calc.net/ . It worked great for setting up networks and not having to spend hours trying to figure out our subnets.

Hope it helps, if not my apologies.

-Azuroth

 

[Valnar]

Yeah, doesn't quite do it. If I had mad Excel skills I could figure something out I suppose.

 

[firedrow]

Here's 2 visual calcs:

http://lightmesh.com/subnet-builder/#eyJhIjoiMS42MS4xNzYuMC8xNyIsIm4iOiIiLCJkIjoiVXNlci1GYWNpbmciLCJzIjpbeyJhIjoiMS42MS4xNzYuMC8yMCIsIm4iOiIiLCJkIjoiVXNlci1GYWNpbmciLCJzIjpbXX0seyJhIjoiMS42MS4xOTIuMC8xOCIsIm4iOiIiLCJkIjoiVXNlci1GYWNpbmciLCJzIjpbXX1dfQ==

http://www.davidc.net/sites/default/subnets/subnets.html