How can I suppress the browser's authentication dialog?
My web application has a login page that submits authentication credentials via an AJAX call. If the user enters the correct username and password, everything is fine, but if not, the following happens:
This is all fine up until step 3. I don't want the dialog to pop up, I want want to handle the 401 response in my AJAX callback function. (For example, by displaying an error message on the login page.) I want the user to re-enter their username and password, of course, but I want them to see my friendly, reassuring login form, not the browser's ugly, default authentication dialog.
Incidentally, I have no control over the server, so having it return a custom status code (ie, something other than a 401) is not an option.
Is there any way I can suppress the authentication dialog? In particular, can I suppress the Authentication Required dialog in Firefox 2 or later? Is there any way to suppress the Connect to [host] dialog in IE 6 and later?
Edit
Additional information from the author (Sept. 18):
I should add that the real problem with the browser's authentication dialog popping up is that it give insufficient information to the user.
The user has just entered a username and password via the form on the login page, he believes he has typed them both correctly, and he has clicked the submit button or hit enter. His expectation is that he will be taken to the next page or perhaps told that he has entered his information incorrectly and should try again. However, he is instead presented with an unexpected dialog box.
The dialog makes no acknowledgment of the fact he just did enter a username and password. It does not clearly state that there was a problem and that he should try again. Instead, the dialog box presents the user with cryptic information like "The site says: '[realm]'." Where [realm] is a short realm name that only a programmer could love.
Web broswer designers take note: no one would ask how to suppress the authentication dialog if the dialog itself were simply more user-friendly. The entire reason that I am doing a login form is that our product management team rightly considers the browsers' authentication dialogs to be awful.
I don't think this is possible -- if you use the browser's HTTP client implementation, it will always pop up that dialog. Two hacks come to mind:
Maybe Flash handles this differently (I haven't tried yet), so having a flash movie make the request might help.
You can set up a 'proxie' for the service that you're accessing on your own server, and have it modify the authentication headers a bit, so that the browser doesn't recognise them.
I encountered the same issue here, and the backend engineer at my company implemented a behavior that is apparently considered a good practice : when a call to a URL returns a 401, if the client has set the header X-Requested-With: XMLHttpRequest , the server drops the www-authenticate header in its response.
The side effect is that the default authentication popup does not appear.
Make sure that your API call has the X-Requested-With header set to XMLHttpRequest . If so there is nothing to do except changing the server behavior according to this good practice...
The browser pops up a login prompt when both of the following conditions are met:
WWW-Authenticate header is present in the response If you can control the HTTP response, then you can remove the WWW-Authenticate header from the response, and the browser won't popup the login dialog.
If you can't control the response, you can setup a proxy to filter out the WWW-Authenticate header from the response.
As far as I know (feel free to correct me if I'm wrong), there is no way to prevent the login prompt once the browser receives the WWW-Authenticate header.
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