I'm sure this question has been answered before on the list (though not by me), but I'll answer it anyway.
Transparent Proxying is actually a violation of HTTP because the browser will assume it is directly connected to the remote server unless specifically configured otherwise. (For more details on why it is a violation, see a thread from earlier today - July 2, 2003) When a browser sends an initial request to the proxy, if the proxy requires authentication it will send a "407 Authorization Required" message (at least I think it's 407 - might be wrong). Included in the reply are the authentication methods the proxy supports. The browser will then select an euthentication method from the list, prompt the user for login info if needed, then send the reply to the proxt for all further requests. This is when the broswer knows about the proxy. With Transparent Proxying, the browser does not know about the proxy. So when it gets the 407 message from the proxy, it treats it as an unsolicited reply - and errors out. Hope that clears it up for you. Adam
