请记住，在一般情况下，您可能有多个正在进行的NAT转换，以及多个dns服务器，每个服务器都运行在不同的NAT转换级别上。

如果您有运营商级NAT，并且想与同一运营商的其他客户通信，该怎么办?在一般情况下，您永远无法确定，因为在每次NAT转换时可能会出现不同的主机名。

前提条件:你必须添加System.Data.Linq引用并引用它

using System.Linq;
string ipAddress ="";
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
ipAddress = Convert.ToString(ipHostInfo.AddressList.FirstOrDefault(address => address.AddressFamily == AddressFamily.InterNetwork));

重构Mrcheif的代码以利用Linq(即. net 3.0+)。

private IPAddress LocalIPAddress()
{
    if (!System.Net.NetworkInformation.NetworkInterface.GetIsNetworkAvailable())
    {
        return null;
    }

    IPHostEntry host = Dns.GetHostEntry(Dns.GetHostName());

    return host
        .AddressList
        .FirstOrDefault(ip => ip.AddressFamily == AddressFamily.InterNetwork);
}

:)

@mrcheif我今天找到了这个答案，这是非常有用的，虽然它确实返回了一个错误的IP(不是由于代码不工作)，但它给出了错误的互联网IP，当你有这样的东西，如Himachi运行。

public static string localIPAddress()
{
    IPHostEntry host;
    string localIP = "";
    host = Dns.GetHostEntry(Dns.GetHostName());

    foreach (IPAddress ip in host.AddressList)
    {
        localIP = ip.ToString();

        string[] temp = localIP.Split('.');

        if (ip.AddressFamily == AddressFamily.InterNetwork && temp[0] == "192")
        {
            break;
        }
        else
        {
            localIP = null;
        }
    }

    return localIP;
}

当本地机器上有多个可用ip地址时，有一种更准确的方法。连接UDP套接字并读取其本地端点:

string localIP;
using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, 0))
{
    socket.Connect("8.8.8.8", 65530);
    IPEndPoint endPoint = socket.LocalEndPoint as IPEndPoint;
    localIP = endPoint.Address.ToString();
}

Connect on a UDP socket has the following effect: it sets the destination for Send/Recv, discards all packets from other addresses, and - which is what we use - transfers the socket into "connected" state, settings its appropriate fields. This includes checking the existence of the route to the destination according to the system's routing table and setting the local endpoint accordingly. The last part seems to be undocumented officially but it looks like an integral trait of Berkeley sockets API (a side effect of UDP "connected" state) that works reliably in both Windows and Linux across versions and distributions.

因此，此方法将提供用于连接到指定远程主机的本地地址。没有建立真正的连接，因此指定的远端ip不可达。

我知道这可能是白费力气，但也许这能帮到别人。我到处寻找一种方法来找到我的本地IP地址，但我发现到处都说要使用:

Dns.GetHostEntry(Dns.GetHostName());

I don't like this at all because it just gets all the addresses assigned to your computer. If you have multiple network interfaces (which pretty much all computers do now-a-days) you have no idea which address goes with which network interface. After doing a bunch of research I created a function to use the NetworkInterface class and yank the information out of it. This way I can tell what type of interface it is (Ethernet, wireless, loopback, tunnel, etc.), whether it is active or not, and SOOO much more.

public string GetLocalIPv4(NetworkInterfaceType _type)
{
    string output = "";
    foreach (NetworkInterface item in NetworkInterface.GetAllNetworkInterfaces())
    {
        if (item.NetworkInterfaceType == _type && item.OperationalStatus == OperationalStatus.Up)
        {
            foreach (UnicastIPAddressInformation ip in item.GetIPProperties().UnicastAddresses)
            {
                if (ip.Address.AddressFamily == AddressFamily.InterNetwork)
                {
                    output = ip.Address.ToString();
                }
            }
        }
    }
    return output;
}

现在要获取以太网接口的IPv4地址:

GetLocalIPv4(NetworkInterfaceType.Ethernet);

或者你的无线接口:

GetLocalIPv4(NetworkInterfaceType.Wireless80211);

如果您试图获取无线接口的IPv4地址，但您的计算机没有安装无线卡，它将只返回一个空字符串。以太网接口也是如此。

编辑:

It was pointed out (thanks @NasBanov) that even though this function goes about extracting the IP address in a much better way than using Dns.GetHostEntry(Dns.GetHostName()) it doesn't do very well at supporting multiple interfaces of the same type or multiple IP addresses on a single interface. It will only return a single IP address when there may be multiple addresses assigned. To return ALL of these assigned addresses you could simply manipulate the original function to always return an array instead of a single string. For example:

public static string[] GetAllLocalIPv4(NetworkInterfaceType _type)
{
    List<string> ipAddrList = new List<string>();
    foreach (NetworkInterface item in NetworkInterface.GetAllNetworkInterfaces())
    {
        if (item.NetworkInterfaceType == _type && item.OperationalStatus == OperationalStatus.Up)
        {
            foreach (UnicastIPAddressInformation ip in item.GetIPProperties().UnicastAddresses)
            {
                if (ip.Address.AddressFamily == AddressFamily.InterNetwork)
                {
                    ipAddrList.Add(ip.Address.ToString());
                }
            }
        }
    }
    return ipAddrList.ToArray();
}

现在，这个函数将返回指定接口类型的所有分配地址。现在要获得单个字符串，可以使用. firstordefault()扩展名返回数组中的第一项，如果数组为空，则返回空字符串。

GetLocalIPv4(NetworkInterfaceType.Ethernet).FirstOrDefault();