如果您正在使用CloudFlare， 你可以试试这个扩展方法:

public static class IPhelper
{
    public static string GetIPAddress(this HttpRequest Request)
    {
        if (Request.Headers["CF-CONNECTING-IP"] != null) return Request.Headers["CF-CONNECTING-IP"].ToString();

        if (Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != null) return Request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString();

        return Request.UserHostAddress;
    }
}

then

string IPAddress = Request.GetIPAddress();

使用这个

Dns.GetHostEntry(Dns.GetHostName())

更新: 感谢布鲁诺·洛佩斯。如果可以访问多个ip地址，则需要使用以下方法:

    private string GetUserIP()
    {
        string ipList = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];

        if (!string.IsNullOrEmpty(ipList))
        {
            return ipList.Split(',')[0];
        }

        return Request.ServerVariables["REMOTE_ADDR"];
    }

到目前为止，所有的响应都考虑了非标准化但非常常见的X-Forwarded-For报头。有一个标准化的转发头，它有点难以解析。一些例子如下:

Forwarded: for="_gazonk"
Forwarded: For="[2001:db8:cafe::17]:4711"
Forwarded: for=192.0.2.60;proto=http;by=203.0.113.43
Forwarded: for=192.0.2.43, for=198.51.100.17

我已经编写了一个类，在确定客户端的IP地址时考虑这两个头。

using System;
using System.Web;

namespace Util
{
    public static class IP
    {
        public static string GetIPAddress()
        {
            return GetIPAddress(new HttpRequestWrapper(HttpContext.Current.Request));
        }

        internal static string GetIPAddress(HttpRequestBase request)
        {
            // handle standardized 'Forwarded' header
            string forwarded = request.Headers["Forwarded"];
            if (!String.IsNullOrEmpty(forwarded))
            {
                foreach (string segment in forwarded.Split(',')[0].Split(';'))
                {
                    string[] pair = segment.Trim().Split('=');
                    if (pair.Length == 2 && pair[0].Equals("for", StringComparison.OrdinalIgnoreCase))
                    {
                        string ip = pair[1].Trim('"');

                        // IPv6 addresses are always enclosed in square brackets
                        int left = ip.IndexOf('['), right = ip.IndexOf(']');
                        if (left == 0 && right > 0)
                        {
                            return ip.Substring(1, right - 1);
                        }

                        // strip port of IPv4 addresses
                        int colon = ip.IndexOf(':');
                        if (colon != -1)
                        {
                            return ip.Substring(0, colon);
                        }

                        // this will return IPv4, "unknown", and obfuscated addresses
                        return ip;
                    }
                }
            }

            // handle non-standardized 'X-Forwarded-For' header
            string xForwardedFor = request.Headers["X-Forwarded-For"];
            if (!String.IsNullOrEmpty(xForwardedFor))
            {
                return xForwardedFor.Split(',')[0];
            }

            return request.UserHostAddress;
        }
    }
}

下面是我用来验证我的解决方案的一些单元测试:

using System.Collections.Specialized;
using System.Web;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UtilTests
{
    [TestClass]
    public class IPTests
    {
        [TestMethod]
        public void TestForwardedObfuscated()
        {
            var request = new HttpRequestMock("for=\"_gazonk\"");
            Assert.AreEqual("_gazonk", Util.IP.GetIPAddress(request));
        }

        [TestMethod]
        public void TestForwardedIPv6()
        {
            var request = new HttpRequestMock("For=\"[2001:db8:cafe::17]:4711\"");
            Assert.AreEqual("2001:db8:cafe::17", Util.IP.GetIPAddress(request));
        }

        [TestMethod]
        public void TestForwardedIPv4()
        {
            var request = new HttpRequestMock("for=192.0.2.60;proto=http;by=203.0.113.43");
            Assert.AreEqual("192.0.2.60", Util.IP.GetIPAddress(request));
        }

        [TestMethod]
        public void TestForwardedIPv4WithPort()
        {
            var request = new HttpRequestMock("for=192.0.2.60:443;proto=http;by=203.0.113.43");
            Assert.AreEqual("192.0.2.60", Util.IP.GetIPAddress(request));
        }

        [TestMethod]
        public void TestForwardedMultiple()
        {
            var request = new HttpRequestMock("for=192.0.2.43, for=198.51.100.17");
            Assert.AreEqual("192.0.2.43", Util.IP.GetIPAddress(request));
        }
    }

    public class HttpRequestMock : HttpRequestBase
    {
        private NameValueCollection headers = new NameValueCollection();

        public HttpRequestMock(string forwarded)
        {
            headers["Forwarded"] = forwarded;
        }

        public override NameValueCollection Headers
        {
            get { return this.headers; }
        }
    }
}

Try:

using System.Net;

public static string GetIpAddress()  // Get IP Address
{
    string ip = "";     
    IPHostEntry ipEntry = Dns.GetHostEntry(GetCompCode());
    IPAddress[] addr = ipEntry.AddressList;
    ip = addr[2].ToString();
    return ip;
}
public static string GetCompCode()  // Get Computer Name
{   
    string strHostName = "";
    strHostName = Dns.GetHostName();
    return strHostName;
}

你能做的是存储你的用户的路由器IP和转发的IP，并尝试使用IP[外部公共和内部私有]使其可靠。但几天后，客户端可能会从路由器分配新的内部IP，但它会更可靠。