How to block modification of a VPN profile ? (password and address)

Question

Hello,
we use iPhone Configuration Utility 2.2 to deploy the iPhone in our Enterprise and we are surprised by the fact that it's impossible to block the modifications a parameter configured in the profile.
For example, for VPN, it's possible for the end-user to change the address of connection.
But our biggest problem is that it's impossible to have a rule that will ask the VPN password to the user every time he wants to connect.
It's really a lack of security because if the password is stored in the VPN configuration then everybody with the iPhone unlocked in his hand can connect to the Enterprise !!!
Is there a way to block such a thing ?
Thank you for your help, it's really important for us.

Answer 1

Also, try to log the username/password in your authenticator, just to be sure that credentials changeGood piece of advice, michael. Worth of it. When I changed the credentials manually, it worked correctly,but from the application, when I logout from 'a', 'a' and log in to 'b', 'b', I got a valuable information.
I tried debugging like given below for checking from the application.
class MyAuthenticator extends Authenticator {
    protected PasswordAuthentication getPasswordAuthentication() {
         System.out.println("userrrrrrrrr"+UtilsHTTPS.username);
         System.out.println("pwdddddddddd"+UtilsHTTPS.password);
  .........................................The information I got while debugging from the application was, the username and password does not get printed. It implies that, Authenticator.setDefault(new MyAuthenticator()); does not work as desired ie; even on calling new MyAuthenticator(), it does not get inside the MyAuthenticator class.
Why does this happen? What is the solution for this?