Find IP Address in ASP.NET Behind Proxy

public string IpAddress()
{
string strIpAddress;
strIpAddress = Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (strIpAddress == null)
{
strIpAddress = Request.ServerVariables["REMOTE_ADDR"];
}
return strIpAddress;
}

To find IP address of a machine behind LAN you can use this code

string strHostName = System.Net.Dns.GetHostName();
string clientIPAddress = System.Net.Dns.GetHostAddresses
(strHostName).GetValue(1).ToString();