web-dev-qa-db-ja.com

IPアドレスが特定のサブネット内にあるかどうかを確認する方法

10.132.0.0/20という形式のサブネットと、ASP.NetリクエストオブジェクトのIPアドレスがあります。

IPアドレスが指定されたサブネット内にあるかどうかを確認するための.NETフレームワーク関数はありますか？

そうでない場合、どのようにそれを行うことができますか？ビット操作だと思いますか？

c#ip-addresssubnet
30
Ryan Michela

回答を使用 Thomasから および Chris とともに Ciscos Subnetting Examples CIDR表記を使用する場合、IPv4およびIPv6で動作するようになりました（ IPAddress/PrefixLength）。私のIPv6-Implementationは少し単純すぎるかもしれませんが、UInt128データ型がないので、Thomasのソリューションを適応できませんでした。うまくいくと思われるコードは次のとおりです。

public static bool IsInSubnet(this IPAddress address, string subnetMask)
        {
            var slashIdx = subnetMask.IndexOf("/");
            if (!subnetMask.Contains("/"))
            { // We only handle netmasks in format "IP/PrefixLength".
                throw new NotSupportedException("Only SubNetMasks with a given prefix length are supported.");
            }

            // First parse the address of the netmask before the prefix length.
            var maskAddress = IPAddress.Parse(subnetMask.Substring(0, slashIdx));

            if (maskAddress.AddressFamily != address.AddressFamily)
            { // We got something like an IPV4-Address for an IPv6-Mask. This is not valid.
                return false;
            }

            // Now find out how long the prefix is.
            int maskLength = int.Parse(subnetMask.Substring(slashIdx + 1));

            if (maskAddress.AddressFamily == AddressFamily.InterNetwork)
            {
                // Convert the mask address to an unsigned integer.
                var maskAddressBits = BitConverter.ToUInt32(maskAddress.GetAddressBytes().Reverse().ToArray());

                // And convert the IpAddress to an unsigned integer.
                var ipAdressBits = BitConverter.ToUInt32(address.GetAddressBytes().Reverse().ToArray());

                // Get the mask/network address as unsigned integer.
                uint mask = uint.MaxValue << (32 - maskLength);

                // https://stackoverflow.com/a/1499284/3085985
                // Bitwise AND mask and MaskAddress, this should be the same as mask and IpAddress
                // as the end of the mask is 0000 which leads to both addresses to end with 0000
                // and to start with the prefix.
                return (maskAddressBits & mask) == (ipAdressBits & mask);
            }

            if (maskAddress.AddressFamily == AddressFamily.InterNetworkV6)
            {
                // Convert the mask address to a BitArray.
                var maskAddressBits = new BitArray(maskAddress.GetAddressBytes());

                // And convert the IpAddress to a BitArray.
                var ipAdressBits = new BitArray(address.GetAddressBytes());

                if (maskAddressBits.Length != ipAdressBits.Length)
                {
                    throw new ArgumentException("Length of IP Address and Subnet Mask do not match.");
                }

                // Compare the prefix bits.
                for (int i = 0; i < maskLength; i++)
                {
                    if (ipAdressBits[i] != maskAddressBits[i])
                    {
                        return false;
                    }
                }

                return true;
            }

            throw new NotSupportedException("Only InterNetworkV6 or InterNetwork address families are supported.");
        }

そして、これは私がそれをテストしたXUnitテストです：

public class IpAddressExtensionsTests
    {
        [Theory]
        [InlineData("192.168.5.85/24", "192.168.5.1")]
        [InlineData("192.168.5.85/24", "192.168.5.254")]
        [InlineData("10.128.240.50/30", "10.128.240.48")]
        [InlineData("10.128.240.50/30", "10.128.240.49")]
        [InlineData("10.128.240.50/30", "10.128.240.50")]
        [InlineData("10.128.240.50/30", "10.128.240.51")]
        public void IpV4SubnetMaskMatchesValidIpAddress(string netMask, string ipAddress)
        {
            var ipAddressObj = IPAddress.Parse(ipAddress);
            Assert.True(ipAddressObj.IsInSubnet(netMask));
        }

        [Theory]
        [InlineData("192.168.5.85/24", "192.168.4.254")]
        [InlineData("192.168.5.85/24", "191.168.5.254")]
        [InlineData("10.128.240.50/30", "10.128.240.47")]
        [InlineData("10.128.240.50/30", "10.128.240.52")]
        [InlineData("10.128.240.50/30", "10.128.239.50")]
        [InlineData("10.128.240.50/30", "10.127.240.51")]
        public void IpV4SubnetMaskDoesNotMatchInvalidIpAddress(string netMask, string ipAddress)
        {
            var ipAddressObj = IPAddress.Parse(ipAddress);
            Assert.False(ipAddressObj.IsInSubnet(netMask));
        }

        [Theory]
        [InlineData("2001:db8:abcd:0012::0/64", "2001:0DB8:ABCD:0012:0000:0000:0000:0000")]
        [InlineData("2001:db8:abcd:0012::0/64", "2001:0DB8:ABCD:0012:FFFF:FFFF:FFFF:FFFF")]
        [InlineData("2001:db8:abcd:0012::0/64", "2001:0DB8:ABCD:0012:0001:0000:0000:0000")]
        [InlineData("2001:db8:abcd:0012::0/64", "2001:0DB8:ABCD:0012:FFFF:FFFF:FFFF:FFF0")]
        [InlineData("2001:db8:abcd:0012::0/128", "2001:0DB8:ABCD:0012:0000:0000:0000:0000")]
        public void IpV6SubnetMaskMatchesValidIpAddress(string netMask, string ipAddress)
        {
            var ipAddressObj = IPAddress.Parse(ipAddress);
            Assert.True(ipAddressObj.IsInSubnet(netMask));
        }

        [Theory]
        [InlineData("2001:db8:abcd:0012::0/64", "2001:0DB8:ABCD:0011:FFFF:FFFF:FFFF:FFFF")]
        [InlineData("2001:db8:abcd:0012::0/64", "2001:0DB8:ABCD:0013:0000:0000:0000:0000")]
        [InlineData("2001:db8:abcd:0012::0/64", "2001:0DB8:ABCD:0013:0001:0000:0000:0000")]
        [InlineData("2001:db8:abcd:0012::0/64", "2001:0DB8:ABCD:0011:FFFF:FFFF:FFFF:FFF0")]
        [InlineData("2001:db8:abcd:0012::0/128", "2001:0DB8:ABCD:0012:0000:0000:0000:0001")]
        public void IpV6SubnetMaskDoesNotMatchInvalidIpAddress(string netMask, string ipAddress)
        {
            var ipAddressObj = IPAddress.Parse(ipAddress);
            Assert.False(ipAddressObj.IsInSubnet(netMask));
        }
    }

テストのベースとして、 Ciscos Subnetting Examples および IBMs IPV6 address examples を使用しました。

私は誰かがこれが役に立ったと思います;）

3
Compufreak

MSDNブログの C＃によるIPアドレスの計算 をご覧ください。それはあなたのニーズと他のいくつかの便利さを満たす必要がある拡張メソッド（IsInSameSubnet）を含んでいます。

public static class IPAddressExtensions
{
    public static IPAddress GetBroadcastAddress(this IPAddress address, IPAddress subnetMask)
    {
        byte[] ipAdressBytes = address.GetAddressBytes();
        byte[] subnetMaskBytes = subnetMask.GetAddressBytes();

        if (ipAdressBytes.Length != subnetMaskBytes.Length)
            throw new ArgumentException("Lengths of IP address and subnet mask do not match.");

        byte[] broadcastAddress = new byte[ipAdressBytes.Length];
        for (int i = 0; i < broadcastAddress.Length; i++)
        {
            broadcastAddress[i] = (byte)(ipAdressBytes[i] | (subnetMaskBytes[i] ^ 255));
        }
        return new IPAddress(broadcastAddress);
    }

    public static IPAddress GetNetworkAddress(this IPAddress address, IPAddress subnetMask)
    {
        byte[] ipAdressBytes = address.GetAddressBytes();
        byte[] subnetMaskBytes = subnetMask.GetAddressBytes();

        if (ipAdressBytes.Length != subnetMaskBytes.Length)
            throw new ArgumentException("Lengths of IP address and subnet mask do not match.");

        byte[] broadcastAddress = new byte[ipAdressBytes.Length];
        for (int i = 0; i < broadcastAddress.Length; i++)
        {
            broadcastAddress[i] = (byte)(ipAdressBytes[i] & (subnetMaskBytes[i]));
        }
        return new IPAddress(broadcastAddress);
    }

    public static bool IsInSameSubnet(this IPAddress address2, IPAddress address, IPAddress subnetMask)
    {
        IPAddress network1 = address.GetNetworkAddress(subnetMask);
        IPAddress network2 = address2.GetNetworkAddress(subnetMask);

        return network1.Equals(network2);
    }
}
28
Chris Shouts

ビット操作は機能します。 IPを32ビットの符号なし整数に詰め込み、サブネットのアドレスと同じことを行い、_&_- maskと0xFFFFFFFF << (32-20)の両方で比較します。

_unsigned int net = ..., ip = ...;
int network_bits = 20;
unsigned int mask = 0xFFFFFFFF << (32 - network_bits);
if ((net & mask) == (ip & mask)) {
  // ...
}
_
13
Thomas

MSDNのブログコードはブロードキャストに依存しており、IPv6にはブロードキャストがないため、IPv6で動作するかどうかはわかりません。

私はこれらの方法で終わりました（nu everestに感謝します）。 CIDR表記（「1.2.3.4/5」）からサブネットとマスクを取得し、アドレスがこのネットワーク内にあるかどうかを確認できます。

これはIPv4およびIPv6で機能します。

public static class IpAddresses
{
    public static Tuple<IPAddress, IPAddress> GetSubnetAndMaskFromCidr(string cidr)
    {
        var delimiterIndex = cidr.IndexOf('/');
        string ipSubnet = cidr.Substring(0, delimiterIndex);
        string mask = cidr.Substring(delimiterIndex + 1);

        var subnetAddress = IPAddress.Parse(ipSubnet);

        if (subnetAddress.AddressFamily == AddressFamily.InterNetworkV6)
        {
            // ipv6
            var ip = BigInteger.Parse("00FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF", NumberStyles.HexNumber) << (128 - int.Parse(mask));

            var maskBytes = new[]
            {
                (byte)((ip & BigInteger.Parse("00FF000000000000000000000000000000", NumberStyles.HexNumber)) >> 120),
                (byte)((ip & BigInteger.Parse("0000FF0000000000000000000000000000", NumberStyles.HexNumber)) >> 112),
                (byte)((ip & BigInteger.Parse("000000FF00000000000000000000000000", NumberStyles.HexNumber)) >> 104),
                (byte)((ip & BigInteger.Parse("00000000FF000000000000000000000000", NumberStyles.HexNumber)) >> 96),
                (byte)((ip & BigInteger.Parse("0000000000FF0000000000000000000000", NumberStyles.HexNumber)) >> 88),
                (byte)((ip & BigInteger.Parse("000000000000FF00000000000000000000", NumberStyles.HexNumber)) >> 80),
                (byte)((ip & BigInteger.Parse("00000000000000FF000000000000000000", NumberStyles.HexNumber)) >> 72),
                (byte)((ip & BigInteger.Parse("0000000000000000FF0000000000000000", NumberStyles.HexNumber)) >> 64),
                (byte)((ip & BigInteger.Parse("000000000000000000FF00000000000000", NumberStyles.HexNumber)) >> 56),
                (byte)((ip & BigInteger.Parse("00000000000000000000FF000000000000", NumberStyles.HexNumber)) >> 48),
                (byte)((ip & BigInteger.Parse("0000000000000000000000FF0000000000", NumberStyles.HexNumber)) >> 40),
                (byte)((ip & BigInteger.Parse("000000000000000000000000FF00000000", NumberStyles.HexNumber)) >> 32),
                (byte)((ip & BigInteger.Parse("00000000000000000000000000FF000000", NumberStyles.HexNumber)) >> 24),
                (byte)((ip & BigInteger.Parse("0000000000000000000000000000FF0000", NumberStyles.HexNumber)) >> 16),
                (byte)((ip & BigInteger.Parse("000000000000000000000000000000FF00", NumberStyles.HexNumber)) >> 8),
                (byte)((ip & BigInteger.Parse("00000000000000000000000000000000FF", NumberStyles.HexNumber)) >> 0),
            };

            return Tuple.Create(subnetAddress, new IPAddress(maskBytes));
        }
        else
        {
            // ipv4
            uint ip = 0xFFFFFFFF << (32 - int.Parse(mask));

            var maskBytes = new[]
            {
                (byte)((ip & 0xFF000000) >> 24),
                (byte)((ip & 0x00FF0000) >> 16),
                (byte)((ip & 0x0000FF00) >> 8),
                (byte)((ip & 0x000000FF) >> 0),
            };

            return Tuple.Create(subnetAddress, new IPAddress(maskBytes));
        }
    }

    public static bool IsAddressOnSubnet(IPAddress address, IPAddress subnet, IPAddress mask)
    {
        byte[] addressOctets = address.GetAddressBytes();
        byte[] subnetOctets = mask.GetAddressBytes();
        byte[] networkOctets = subnet.GetAddressBytes();

        // ensure that IPv4 isn't mixed with IPv6
        if (addressOctets.Length != subnetOctets.Length
            || addressOctets.Length != networkOctets.Length)
        {
            return false;
        }

        for (int i = 0; i < addressOctets.Length; i += 1)
        {
            var addressOctet = addressOctets[i];
            var subnetOctet = subnetOctets[i];
            var networkOctet = networkOctets[i];

            if (networkOctet != (addressOctet & subnetOctet))
            {
                return false;
            }
        }
        return true;
    }
}

使用例：

var subnetAndMask = IpAddresses.GetSubnetAndMaskFromCidr("10.132.0.0/20");
bool result = IpAddresses.IsAddressOnSubnet(
    IPAddress.Parse("10.132.12.34"),
    subnetAndMask.Item1,
    subnetAndMask.Item2);
4
Oliver Schimmer

私はここのパーティーに遅れましたが、同様のニーズがあり、これを正確に行うためのクイックパッケージをまとめました。

https://www.nuget.org/packages/IpMatcher/

およびソース：

https://github.com/jchristn/IpMatcher

簡単な使用：

using IpMatcher;

Matcher matcher = new Matcher();
matcher.Add("192.168.1.0", "255.255.255.0");
matcher.Add("192.168.2.0", "255.255.255.0");
matcher.Remove("192.168.2.0");
matcher.Exists("192.168.1.0", "255.255.255.0");  // true
matcher.Match("192.168.1.34"); // true
matcher.Match("10.10.10.10");  // false
2
joelc

解決策は、System.Net.IPAddressを使用してIPアドレスをバイトに変換し、アドレス、サブネット、およびマスクオクテットでビットごとの比較を実行することです。

バイナリAND演算子&は、両方のオペランドに存在する場合、結果にビットをコピーします。

コード：

using System.Net;   // Used to access IPAddress

bool IsAddressOnSubnet(string address, string subnet, string mask)
{
    try
    {
        IPAddress Address = IPAddress.Parse(address);
        IPAddress Subnet = IPAddress.Parse(subnet);
        IPAddress Mask = IPAddress.Parse(mask);            

        Byte[] addressOctets = Address.GetAddressBytes();
        Byte[] subnetOctets = Mask.GetAddressBytes();
        Byte[] networkOctets = Subnet.GetAddressBytes();

        return
            ((networkOctets[0] & subnetOctets[0]) == (addressOctets[0] & subnetOctets[0])) &&
            ((networkOctets[1] & subnetOctets[1]) == (addressOctets[1] & subnetOctets[1])) &&
            ((networkOctets[2] & subnetOctets[2]) == (addressOctets[2] & subnetOctets[2])) &&
            ((networkOctets[3] & subnetOctets[3]) == (addressOctets[3] & subnetOctets[3]));
    }
    catch (System.Exception ex)
    {
        return false;                
    }
}

Спасибоに感謝します！ рекрасноерешение！ 参考

1
nu everest