[cups] [1.6.4 debian] how to reset web UI admin basicauth?

[Tom Roche]

summary: newly setup debian box with cups version=1.6.4. I used wrong credentials for the CUPS basic authentication when first trying to http://localhost:631/>Administration>Add Printer. How to restore initial condition, so that I no longer get "Unable to add printer: Forbidden"?

details:

I have 3 linux boxes, each with LMDE (Linux Mint Debian Edition) based on debian testing.

* box1 has an older LMDE version, with working CUPS (version=1.5.2) that prints to my local printer (a Brother mono laser).
* box2 has a fresh install of the latest LMDE version (201403/UP8) which ships with CUPS version=1.6.4. CUPS works on box2, but I seem to have hosed the printer install, so I'm trying to debug that with ...
* box3 also has a fresh install of the latest LMDE.

On box3 I browsed (using Firefox) to http://localhost:631/ and to Administration>Add Printer. At the basicauth dialog I entered the wrong credentials for that box :-( Now when I hit the button to Add Printer, I get error="Unable to add printer: Forbidden"

I thought I could restore CUPS to its initial condition by just un/reloading its packages, so on box3 I did the sequence

1. `sudo aptitude purge cups` and its dependencies
2. `sudo aptitude update`
3. `sudo aptitude install cups` and its dependencies
4. browse to http://localhost:631/>Administration>Add Printer

but instead of getting a fresh basicauth dialog, I again got error="Unable to add printer: Forbidden" :-( so I'm guessing these credentials are managed by the browser or something else. How to reset basicauth for http://localhost:631/>Administration?

Apologies if this is a FAQ, but I didn't see answers @

http://www.cups.org/faq.php

or by searching the CUPS-1.6 docs or this list's archives. (Feel free to point to doc--I can usually semi-competently RTFM :-)

TIA, Tom Roche <Tom_Roche at pobox.com>