如何确定私有IP地址？

Question

到目前为止,我有这个代码:

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);
  }
}

如何过滤私有IP地址？我以同样的方式过滤环回IP地址.

Answer 1

更详细的回复如下:

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.他们是:

• 10.0.0.0 - 10.255.255.255(10/8前缀)
• 172.16.0.0 - 172.31.255.255(172.16/12前缀)
• 192.168.0.0 - 192.168.255.255(192.168/16前缀)

您可能还希望过滤掉RFC3927中定义的链接本地地址(169.254/16).

Answer 3

此实施+测试涵盖：

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• 环回（IPv4、IPv6）
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• 本地链接（IPv4、IPv6）
\n
• 站点本地 (IPv6)
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• 唯一本地（IPv6，需要.NET6）
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• IPv4 映射到 IPv6
\n

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在 .NET Core 3.1 和 .NET 6 上测试。

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https://gist.github.com/angularsen/f77b53ee9966fcd914025e25a2b3a085

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执行

\n

using System;\nusing System.Net;\nusing System.Net.Sockets;\n\nnamespace MyNamespace\n{\n    /// <summary>\n    /// Extension methods on <see cref="System.Net.IPAddress"/>.\n    /// </summary>\n    public static class IPAddressExtensions\n    {\n        /// <summary>\n        /// Returns true if the IP address is in a private range.<br/>\n        /// IPv4: Loopback, link local ("169.254.x.x"), class A ("10.x.x.x"), class B ("172.16.x.x" to "172.31.x.x") and class C ("192.168.x.x").<br/>\n        /// IPv6: Loopback, link local, site local, unique local and private IPv4 mapped to IPv6.<br/>\n        /// </summary>\n        /// <param name="ip">The IP address.</param>\n        /// <returns>True if the IP address was in a private range.</returns>\n        /// <example><code>bool isPrivate = IPAddress.Parse("127.0.0.1").IsPrivate();</code></example>\n        public static bool IsPrivate(this IPAddress ip)\n        {\n            // Map back to IPv4 if mapped to IPv6, for example "::ffff:1.2.3.4" to "1.2.3.4".\n            if (ip.IsIPv4MappedToIPv6)\n                ip = ip.MapToIPv4();\n\n            // Checks loopback ranges for both IPv4 and IPv6.\n            if (IPAddress.IsLoopback(ip)) return true;\n\n            // IPv4\n            if (ip.AddressFamily == AddressFamily.InterNetwork)\n                return IsPrivateIPv4(ip.GetAddressBytes());\n\n            // IPv6\n            if (ip.AddressFamily == AddressFamily.InterNetworkV6)\n            {\n                return ip.IsIPv6LinkLocal ||\n#if NET6_0\n                       ip.IsIPv6UniqueLocal ||\n#endif\n                       ip.IsIPv6SiteLocal;\n            }\n\n            throw new NotSupportedException(\n                    $"IP address family {ip.AddressFamily} is not supported, expected only IPv4 (InterNetwork) or IPv6 (InterNetworkV6).");\n        }\n\n        private static bool IsPrivateIPv4(byte[] ipv4Bytes)\n        {\n            // Link local (no IP assigned by DHCP): 169.254.0.0 to 169.254.255.255 (169.254.0.0/16)\n            bool IsLinkLocal() => ipv4Bytes[0] == 169 && ipv4Bytes[1] == 254;\n\n            // Class A private range: 10.0.0.0 \xe2\x80\x93 10.255.255.255 (10.0.0.0/8)\n            bool IsClassA() => ipv4Bytes[0] == 10;\n\n            // Class B private range: 172.16.0.0 \xe2\x80\x93 172.31.255.255 (172.16.0.0/12)\n            bool IsClassB() => ipv4Bytes[0] == 172 && ipv4Bytes[1] >= 16 && ipv4Bytes[1] <= 31;\n\n            // Class C private range: 192.168.0.0 \xe2\x80\x93 192.168.255.255 (192.168.0.0/16)\n            bool IsClassC() => ipv4Bytes[0] == 192 && ipv4Bytes[1] == 168;\n\n            return IsLinkLocal() || IsClassA() || IsClassC() || IsClassB();\n        }\n    }\n}\n

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测试

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using System.Diagnostics.CodeAnalysis;\nusing System.Net;\nusing MyNamespace;\nusing FluentAssertions;\nusing Xunit;\n\nnamespace MyNamespace.Tests\n{\n    [SuppressMessage("ReSharper", "InvokeAsExtensionMethod")]\n    public class IPAddressExtensionsTests\n    {\n        [Theory]\n        [InlineData("1.1.1.1"     )] // Cloudflare DNS\n        [InlineData("8.8.8.8"     )] // Google DNS\n        [InlineData("20.112.52.29")] // microsoft.com\n        public void IsPrivate_ReturnsFalse_PublicIPv4(string ip)\n        {\n            var ipAddress = IPAddress.Parse(ip);\n            IPAddressExtensions.IsPrivate(ipAddress).Should().BeFalse();\n        }\n\n        [Theory]\n        [InlineData("::ffff:1.1.1.1"     )] // Cloudflare DNS\n        [InlineData("::ffff:8.8.8.8"     )] // Google DNS\n        [InlineData("::ffff:20.112.52.29")] // microsoft.com\n        public void IsPrivate_ReturnsFalse_PublicIPv4MappedToIPv6(string ip)\n        {\n            var ipAddress = IPAddress.Parse(ip);\n            IPAddressExtensions.IsPrivate(ipAddress).Should().BeFalse();\n        }\n\n        [Theory]\n        [InlineData("127.0.0.1"      )] // Loopback IPv4 127.0.0.1 - 127.255.255.255 (127.0.0.0/8)\n        [InlineData("127.10.20.30"   )]\n        [InlineData("127.255.255.255")]\n        [InlineData("10.0.0.0"       )] // Class A private IP 10.0.0.0 \xe2\x80\x93 10.255.255.255 (10.0.0.0/8)\n        [InlineData("10.20.30.40"    )]\n        [InlineData("10.255.255.255" )]\n        [InlineData("172.16.0.0"     )] // Class B private IP 172.16.0.0 \xe2\x80\x93 172.31.255.255 (172.16.0.0/12)\n        [InlineData("172.20.30.40"   )]\n        [InlineData("172.31.255.255" )]\n        [InlineData("192.168.0.0"    )] // Class C private IP 192.168.0.0 \xe2\x80\x93 192.168.255.255 (192.168.0.0/16)\n        [InlineData("192.168.30.40"  )]\n        [InlineData("192.168.255.255")]\n        [InlineData("169.254.0.0"    )] // Link local (169.254.x.x)\n        [InlineData("169.254.30.40"  )]\n        [InlineData("169.254.255.255")]\n        public void IsPrivate_ReturnsTrue_PrivateIPv4(string ip)\n        {\n            var ipAddress = IPAddress.Parse(ip);\n            IPAddressExtensions.IsPrivate(ipAddress).Should().BeTrue();\n        }\n\n        [Theory]\n        [InlineData("::ffff:127.0.0.1"      )] // Loopback IPv4 127.0.0.1 - 127.255.255.254 (127.0.0.0/8)\n        [InlineData("::ffff:127.10.20.30"   )]\n        [InlineData("::ffff:127.255.255.254")]\n        [InlineData("::ffff:10.0.0.0"       )] // Class A private IP 10.0.0.0 \xe2\x80\x93 10.255.255.255 (10.0.0.0/8)\n        [InlineData("::ffff:10.20.30.40"    )]\n        [InlineData("::ffff:10.255.255.255" )]\n        [InlineData("::ffff:172.16.0.0"     )] // Class B private IP 172.16.0.0 \xe2\x80\x93 172.31.255.255 (172.16.0.0/12)\n        [InlineData("::ffff:172.20.30.40"   )]\n        [InlineData("::ffff:172.31.255.255" )]\n        [InlineData("::ffff:192.168.0.0"    )] // Class C private IP 192.168.0.0 \xe2\x80\x93 192.168.255.255 (192.168.0.0/16)\n        [InlineData("::ffff:192.168.30.40"  )]\n        [InlineData("::ffff:192.168.255.255")]\n        [InlineData("::ffff:169.254.0.0"    )] // Link local (169.254.x.x)\n        [InlineData("::ffff:169.254.30.40"  )]\n        [InlineData("::ffff:169.254.255.255")]\n        public void IsPrivate_ReturnsTrue_PrivateIPv4MappedToIPv6(string ip)\n        {\n            var ipAddress = IPAddress.Parse(ip);\n            IPAddressExtensions.IsPrivate(ipAddress).Should().BeTrue();\n        }\n\n        [Theory]\n        [InlineData("::1"              )]  // Loopback\n        [InlineData("fe80::"           )]  // Link local\n        [InlineData("fe80:1234:5678::1")]  // Link local\n        [InlineData("fc00::"           )]  // Unique local, globally assigned.\n        [InlineData("fc00:1234:5678::1")]  // Unique local, globally assigned.\n        [InlineData("fd00::"           )]  // Unique local, locally assigned.\n        [InlineData("fd12:3456:789a::1")]  // Unique local, locally assigned.\n        public void IsPrivate_ReturnsTrue_PrivateIPv6(string ip)\n        {\n            var ipAddress = IPAddress.Parse(ip);\n            IPAddressExtensions.IsPrivate(ipAddress).Should().BeTrue();\n        }\n\n        [Theory]\n        [InlineData("2606:4700:4700::64"                     )] // Cloudflare DNS\n        [InlineData("2001:4860:4860::8888"                   )] // Google DNS\n        [InlineData("2001:0db8:85a3:0000:0000:8a2e:0370:7334")] // Commonly used example.\n        public void IsPrivate_ReturnsFalse_PublicIPv6(string ip)\n        {\n            var ipAddress = IPAddress.Parse(ip);\n            IPAddressExtensions.IsPrivate(ipAddress).Should().BeFalse();\n        }\n    }\n}\n

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Answer 4

执行此操作的最佳方法是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)
    {
        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地址类的实例上调用该方法

    bool isIpInternal = ipAddressInformation.Address.IsInternal();

Answer 5

添加了IPv6和localhost的情况。

    /* An IP should be considered as internal when:

       ::1          -   IPv6  loopback
       10.0.0.0     -   10.255.255.255  (10/8 prefix)
       127.0.0.0    -   127.255.255.255  (127/8 prefix)
       172.16.0.0   -   172.31.255.255  (172.16/12 prefix)
       192.168.0.0  -   192.168.255.255 (192.168/16 prefix)
     */
    public bool IsInternal(string testIp)
    {
        if(testIp == "::1") return true;

        byte[] ip = IPAddress.Parse(testIp).GetAddressBytes();
        switch (ip[0])
        {
            case 10:
            case 127:
                return true;
            case 172:
                return ip[1] >= 16 && ip[1] < 32;
            case 192:
                return ip[1] == 168;
            default:
                return false;
        }
    }