In this article I will explain with an example, how to get Client IP Address of Visitor’s Machine in ASP.Net using C# and VB.Net.
This article will explain how to get IP Address of Visitors (Client) Machines which don’t use Proxy Servers and also which are behind Proxy Servers in ASP.Net using C# and VB.Net. 
How to get IP Address of Visitors Machine in ASP.Net
First the IP Address is determined for the Client machine’s which are behind Routers or Proxy Servers and hence the HTTP_X_FORWARDED_FOR server variable is checked.
Note: When the Client machine is behind a Proxy Server its IP Address of the Proxy Server is appended to the Client machine’s IP Address. If there are multiple Proxy Servers then the IP Addresses of all the Proxy Servers are appended to the client machine IP Address.
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: While running this application on your machine locally i.e. in Visual Studio, the IP Address will show as or ::1. This happens because in such case the Client and Server both are the same machine. Thus no need to worry when you deploy it on a Server, you will see the results.
string ipaddress;
ipaddress = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (ipaddress == "" || ipaddress == null)
    ipaddress = Request.ServerVariables["REMOTE_ADDR"];
Dim ipaddress As String
ipaddress = Request.ServerVariables("HTTP_X_FORWARDED_FOR")
If ipaddress = "" Or ipaddress Is Nothing Then
   ipaddress = Request.ServerVariables("REMOTE_ADDR")
End If
View Demo