如何判断IP地址是否私有？

Question

到目前为止，我有以下代码：

NetworkInterface[] adapters = NetworkInterface.GetAllNetworkInterfaces();

foreach (NetworkInterface adapter in adapters)
{
  IPInterfaceProperties properties = adapter.GetIPProperties();

  foreach (IPAddressInformation uniCast in properties.UnicastAddresses)
  {

    // Ignore loop-back addresses & IPv6
    if (!IPAddress.IsLoopback(uniCast.Address) && 
      uniCast.Address.AddressFamily!= AddressFamily.InterNetworkV6)
        Addresses.Add(uniCast.Address);
  }
}

如何同时过滤内网IP地址？我以同样的方式过滤环回IP地址。

Answer 1

更详细的回应在这里：

private bool _IsPrivate(string ipAddress)
{
    int[] ipParts = ipAddress.Split(new String[] { "." }, StringSplitOptions.RemoveEmptyEntries)
                             .Select(s => int.Parse(s)).ToArray();
    // in private ip range
    if (ipParts[0] == 10 ||
        (ipParts[0] == 192 && ipParts[1] == 168) ||
        (ipParts[0] == 172 && (ipParts[1] >= 16 && ipParts[1] <= 31))) {
        return true;
    }

    // IP Address is probably public.
    // This doesn't catch some VPN ranges like OpenVPN and Hamachi.
    return false;
}

Answer 2

私有地址范围在RFC1918中定义。它们是：

前缀10.0.0.0- 10.255.255.255 (10/8 prefix)

• 172.16.0.0 - 172.31.255.255 (172.16/12 prefix)

• 192.168.0.0 - 192.168.255.255 (192.168/16
• )

您可能还希望根据RFC3927中的定义过滤掉本地链路地址(169.254/16)。

Answer 3

执行此操作的最佳方法是使用IP地址类的扩展方法

    /// <summary>
    /// An extension method to determine if an IP address is internal, as specified in RFC1918
    /// </summary>
    /// <param name="toTest">The IP address that will be tested</param>
    /// <returns>Returns true if the IP is internal, false if it is external</returns>
    public static bool IsInternal(this IPAddress toTest)
    {
        if (IPAddress.IsLoopback(toTest)) return true;
        else if (toTest.ToString() == "::1") return false;

        byte[] bytes = toTest.GetAddressBytes();
        switch( bytes[ 0 ] )
        {
            case 10:
                return true;
            case 172:
                return bytes[ 1 ] < 32 && bytes[ 1 ] >= 16;
            case 192:
                return bytes[ 1 ] == 168;
            default:
                return false;
        }
    }

然后，可以在IP address类的实例上调用该方法

    bool isIpInternal = ipAddressInformation.Address.IsInternal();