How to get client IP address in a one-way ASMX Web Service

Question

I have a web service that is configured as one way. Or rather, the SoapDocumentMethod attribute has a property that is called "OneWay". That is set to true.

I'm trying to get the IP address of the client request. I get the fact that I won't get the exact IP address because the client may be behind other networking concepts. That's irrelevant. I want an IP address of whoever initiated the call on the service, so if that's some front end server sitting on top of some clients machine, so be it.

I tried using HttpContext, but that doesn't seem to work. If I hit my web service on the same machine as the web service is running, then HttpContext is populated and I can get the IP address. However, any external use of my web service and the HttpContext is a little messed up. It throws exceptions on many of the properties when trying to find out information on the request. So I cannot get the client IP address. If you enable tracing of the service, It then starts working. But that's only a temporary work around. It's not an acceptable solution.

So.. what's the best way to get the client IP address when you have a one way web service?

I've already looked here: http://msdn.microsoft.com/en-us/library/system.web.services.protocols.soapdocumentmethodattribute.oneway.aspx

Answer 1

Luckily, you have some options.

1) Pass the IP address as a parameter --> NOT recommended. 2) Create a SOAP header for the IP Address and pass it from the client

I wrote you a quick sample for option 2.

First, you need to extend SoapHeader and create a class to pass the IP Address.

using System.Web.Services.Protocols;

namespace SoapHeaders
{
    public class IpAddressHeader : SoapHeader
    {
        public string IpAddress;
    }
}

Next, you need to define a web service with that header, and a web method that uses it.

using System;
using System.IO;
using System.Web.Services.Protocols;
using System.Web.Services;
using SoapHeaders;

namespace WebService
{

    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]

    public class SoapHeaderService : System.Web.Services.WebService
    {
        public IpAddressHeader IpAddressHeader;

        [WebMethod]
        [SoapDocumentMethod(OneWay = true)]
        [SoapHeader("IpAddressHeader")]
        public void LogIpAddress()
        {
            var logFile = string.Format(@"C:\Logs\{0:yyyy-MM-dd HH.mm.ss.ffff}.log", DateTime.Now);

            string ipAddress;

            if (IpAddressHeader == null || string.IsNullOrEmpty(IpAddressHeader.IpAddress))
            {
                ipAddress = "?";
            }
            else
            {
                ipAddress = IpAddressHeader.IpAddress;
            }

            File.WriteAllText(logFile, string.Format("Client Address --> {0}", ipAddress));
        }
    }
}

Finally, you need a client to consume the service and pass the header information. I just made a quick console application, but it could be anything, really:

using System.Net;
using ConsoleApplication.soapHeaderServices;

namespace ConsoleApplication
{
    class Program
    {

        static void Main(string[] args)
        {
            var ipAddressHeader = new IpAddressHeader();
            ipAddressHeader.IpAddress = GetIpAddress();

            var serviceClient = new SoapHeaderService();
            serviceClient.IpAddressHeaderValue = ipAddressHeader;

            serviceClient.LogIpAddress();
        }

        static string GetIpAddress()
        {
            var ipAddress = "?";
            var host = Dns.GetHostEntry(Dns.GetHostName());
            foreach (var address in host.AddressList)
            {
                if (address.AddressFamily.ToString() != "InterNetwork")
                {
                    continue;
                }

                ipAddress = address.ToString();
                break;
            }

            return ipAddress;
        }
    }
}

I deployed the service on a remote test service and called it from my PC. Works fine. Contents of the log file created: Client Address --> 192.168.1.41

I hope you find that helpful!

EDIT: DO NOT USE MY BELOW CODE. It is wrong. I'm leaving it as an example of what NOT to do. Server variables are not available in one-way operations.

ORIGINAL ANSWER. DO NOTE USE: See my updated answer above the EDIT.

I just smoke tested this on a new ASP.Net Web Service Application. Works from every endpoint I have access to.

HttpRequest.UserHostAddress is the document way to get the client's IP address. If that is not working for you, I would look for underlying causes.

[WebMethod]
[SoapDocumentMethod(OneWay = true)]
public void Silent()
{
    var address = HttpContext.Current.Request.UserHostAddress;

    // Do something with address
    Trace.Write(address);
}