How to Get the Client's Ip Address in ASP.NET MVC

How can I get the client's IP address in ASP.NET MVC?

The simple answer is to use the HttpRequest.UserHostAddress property.

Example: From within a Controller:

using System;
using System.Web.Mvc;

namespace Mvc.Controllers
{
    public class HomeController : ClientController
    {
        public ActionResult Index()
        {
            string ip = Request.UserHostAddress;

            ...
        }
    }
}

Example: From within a helper class:

using System.Web;

namespace Mvc.Helpers
{
    public static class HelperClass
    {
        public static string GetIPHelper()
        {
            string ip = HttpContext.Current.Request.UserHostAddress;
            ..
        }
    }
}

BUT, if the request has been passed on by one, or more, proxy servers then the IP address returned by HttpRequest.UserHostAddress property will be the IP address of the last proxy server that relayed the request.

Proxy servers MAY use the de facto standard of placing the client's IP address in the X-Forwarded-For HTTP header. Aside from there is no guarantee that a request has a X-Forwarded-For header, there is also no guarantee that the X-Forwarded-For hasn't been SPOOFED.

Original Answer

Request.UserHostAddress

The above code provides the Client's IP address without resorting to looking up a collection. The Request property is available within Controllers (or Views). Therefore instead of passing a Page class to your function you can pass a Request object to get the same result:

public static string getIPAddress(HttpRequestBase request)
{
    string szRemoteAddr = request.UserHostAddress;
    string szXForwardedFor = request.ServerVariables["X_FORWARDED_FOR"];
    string szIP = "";

    if (szXForwardedFor == null)
    {
        szIP = szRemoteAddr;
    }
    else
    {
        szIP = szXForwardedFor;
        if (szIP.IndexOf(",") > 0)
        {
            string [] arIPs = szIP.Split(',');

            foreach (string item in arIPs)
            {
                if (!isPrivateIP(item))
                {
                    return item;
                }
            }
        }
    }
    return szIP;
}

How to get client ip address in MVC

You can get the I.P address like this in your Controller method:

If the client machine is behind a proxy server, we can check for the variable HTTP_X_FORWARDED_FOR:

string ip;
ip =  System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (string.IsNullOrEmpty(ip))
{
    ip =  System.Web.HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
}

If the IP Address is not found in the HTTP_X_FORWARDED_FOR server variable, it means that it is not using any Proxy Server and hence the IP Address is now checked in the REMOTE_ADDR server variable.

Note: On your local machine, the I.P address will be shown as ::1 which is an IPV6 loopback address (i.e. localhost). An IPV4 address would be 127.0.0.1.

This is because in such case the Client and Server both are the same machine. When the application is deployed on the server, then the result will be different.

ASP.NET MVC 5: is there anyway to get the client IP in the Global.asax file?

Something like this should be possible:

string ipAddress = HttpContext.Current.Request.Headers["X-Forwarded-For"];
if (ipAddress == null)
{
    ipAddress = HttpContext.Current.Request.UserHostAddress;
}

First check XFF header and if it's empty, check directly HttpRequest's client IP address.

How to get a user's client IP address in ASP.NET?

As others have said you can't do what you are asking. If you describe the problem you are trying to solve maybe someone can help?

E.g.

are you trying to uniquely identify your users?
Could you use a cookie, or the session ID perhaps instead of the IP address?

Edit The address you see on the server shouldn't be the ISP's address, as you say that would be a huge range. The address for a home user on broadband will be the address at their router, so every device inside the house will appear on the outside to be the same, but the router uses NAT to ensure that traffic is routed to each device correctly. For users accessing from an office environment the address may well be the same for all users. Sites that use IP address for ID run the risk of getting it very wrong - the examples you give are good ones and they often fail. For example my office is in the UK, the breakout point (where I "appear" to be on the internet) is in another country where our main IT facility is, so from my office my IP address appears to be not in the UK. For this reason I can't access UK only web content, such as the BBC iPlayer). At any given time there would be hundreds, or even thousands, of people at my company who appear to be accessing the web from the same IP address.

When you are writing server code you can never be sure what the IP address you see is referring to. Some users like it this way. Some people deliberately use a proxy or VPN to further confound you.

When you say your machine address is different to the IP address shown on StackOverflow, how are you finding out your machine address? If you are just looking locally using ipconfig or something like that I would expect it to be different for the reasons I outlined above. If you want to double check what the outside world thinks have a look at whatismyipaddress.com/.

This Wikipedia link on NAT will provide you some background on this.

How to get client IP address in MVC 4 controller?

Either of these should work, from inside your Controller:

method 1:

string userIpAddress = this.Request.ServerVariables["REMOTE_ADDR"];

method 2:

string userIpAddress = this.Request.UserHostAddress;