using System.Net.Http;

public static class HttpRequestMessageExtensions

{

    private const string HttpContext = "MS_HttpContext";

    private const string RemoteEndpointMessage =

        "System.ServiceModel.Channels.RemoteEndpointMessageProperty";

    private const string OwinContext = "MS_OwinContext";

    public static string GetClientIpAddress(this HttpRequestMessage request)

    {

       // Web-hosting. Needs reference to System.Web.dll

       if (request.Properties.ContainsKey(HttpContext))

       {

           dynamic ctx = request.Properties[HttpContext];

           if (ctx != null)

           {

               return ctx.Request.UserHostAddress;

           }

       }

       // Self-hosting. Needs reference to System.ServiceModel.dll.

       if (request.Properties.ContainsKey(RemoteEndpointMessage))

       {

            dynamic remoteEndpoint = request.Properties[RemoteEndpointMessage];

            if (remoteEndpoint != null)

            {

                return remoteEndpoint.Address;

            }

        }

       // Self-hosting using Owin. Needs reference to Microsoft.Owin.dll.

       if (request.Properties.ContainsKey(OwinContext))

       {

           dynamic owinContext = request.Properties[OwinContext];

           if (owinContext != null)

           {

               return owinContext.Request.RemoteIpAddress;

           }

       }

        return null;

    }

}

References required:

• HttpContextWrapper - System.Web.dll
• RemoteEndpointMessageProperty - System.ServiceModel.dll
• OwinContext - Microsoft.Owin.dll (you will have it already if you use Owin package)

第二种：
((System.Web.HttpContextWrapper)Request.Properties["MS_HttpContext"]).Request.UserHostAddress;