C#クライアントのIPアドレスを取得

public class IPNet
    {
        public static string GetIP4Address()
        {
            string IP4Address = String.Empty;

            foreach (IPAddress IPA in Dns.GetHostAddresses(HttpContext.Current.Request.UserHostAddress))
            {
                if (IPA.AddressFamily.ToString() == "InterNetwork")
                {
                    IP4Address = IPA.ToString();
                    break;
                }
            }

            if (IP4Address != String.Empty)
            {
                return IP4Address;
            }

            foreach (IPAddress IPA in Dns.GetHostAddresses(Dns.GetHostName()))
            {
                if (IPA.AddressFamily.ToString() == "InterNetwork")
                {
                    IP4Address = IPA.ToString();
                    break;
                }
            }
            return IP4Address;
        }
    }