External ip address

 I am building an mvc app, i need to redirect users to different views based on their ip address location.
 I used this "Request.ServerVariables["REMOTE_ADDR"];" and
IPHostEntry ihe = Dns.GetHostEntry(Dns.GetHostName()); IPAddress myself = ihe.AddressList[1];
 but both returns local ip. I need external ip.
 Could you plz help.