Get User's IP Address

Question

How can I get the current visitors IP address?

Answer 1

Edit: also found an interesting question regarding IP-related http headers here.

Edit2: As mentioned in comments and in link I provided above, HTTP_X_FORWARDED_FOR header may contain multiple IP-addresses separated by comma. I didn't face this situation but suppose some corrections to my answer are required.

I use this code to get the IP address (it returns IPAddress.None value if getting failed for some reason):

    /// <summary>
    /// Gets the IP address of the request.
    /// <remarks>
    /// This method is more useful than built in because in some cases it may show real user IP address even under proxy.
    /// <summary>
    /// Gets the IP address of the request.
    /// <remarks>
    /// This method is more useful than built in because in some cases it may show real user IP address even under proxy.
    /// The <see cref="System.Net.IPAddress.None" /> value will be returned if getting is failed.
    /// </remarks>
    /// </summary>
    /// <param name="request">The HTTP request object.</param>
    /// <returns></returns>
    public static IPAddress GetIp(this HttpRequest request)
    {
        string ipString;
        if (string.IsNullOrEmpty(request.ServerVariables["HTTP_X_FORWARDED_FOR"]))
        {
            ipString = request.ServerVariables["REMOTE_ADDR"];
        }
        else
        {
            ipString = request.ServerVariables["HTTP_X_FORWARDED_FOR"].Split(",".ToCharArray(), StringSplitOptions.RemoveEmptyEntries)
                .FirstOrDefault();
        }

        IPAddress result;
        if (!IPAddress.TryParse(ipString, out result))
        {
            result = IPAddress.None;
        }

        return result;
    }

Answer 2

HttpContext.Current.Request.UserHostAddress;

or

HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];

or

HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];