How to see if an IP address belongs inside of a range of IPs using CIDR notation?

Question

Here I have a static reference the ranges I need to check:

private static List Ip_Range = new List()
{
    \"12.144.86.0/23\",
           


        

Answer 1

    public static bool IpIsInRange(string subnet, string ip)
    {
        var splitSubnet = subnet.Split('/');
        var maskBits = 32 - int.Parse(splitSubnet[1]);
        if (maskBits == 32)
        {
            return true;
        }
        var subnetIp = BitConverter.ToInt32(IPAddress.Parse(splitSubnet[0]).GetAddressBytes().Reverse().ToArray(), 0) >> maskBits << maskBits;
        var clientIp = BitConverter.ToInt32(IPAddress.Parse(ip).GetAddressBytes().Reverse().ToArray(), 0) >> maskBits << maskBits;
        return subnetIp == clientIp;
    }