Find if IP is in range

[countdrak]

I have the the CIDR notation. I have the cidr range.

So I have

10.10.10.1/18 and the range 10.10.0.0 - 10.10.63.255

What is the algorithm to see if an IP is in that range. I am trying to write a function in Coldfusion.

so I know 10.10.0.1 is in range but 12.4.2.134 is not. Can someone help. I just need the algorithm.

 

[NFI]

You just need to figure out a way of comparing the first 18 bits of your IP address with your network address, which, in binary, is;

00001010.00001010.00000000.00000000

If these bits are all the same, then your address is within the defined subnet.

How to do that? Well, you need to write some sort of dec2bin function, which shouldn't be too hard and then some sort of recursive FOR EACH...NEXT type loop which compares the bits in your network address with the bits in your IP address...

Alternatively, you could just write some sort of IF statement, which goes along the lines of;

If (intOctetOne = 10 AND intOctetTwo = 10 AND intOctetThree < 64) Then booInSubnet = TRUE

...which I suppose, in retrospect, would actually be a lot easier

Paul