XP bug when talking to CUPS through http proxy

[angelb]

> This posting is mostly for the archives in case someone has
> the same problem and doesn't want to waste a lot of time debugging it.
>
> I think i have hit an annoying bug with Windows XP (including SP2)
> when trying to access a CUPS printer through an http/https proxy,
> _and_ the printer requires authentication.
>
> In our setting, some PCs on a private network need to access
> an external CUPS server through an HTTP proxy. The proxy is
> correctly configured in "Internet Options" on windows.
>
> When you try to "Add a printer" from the Windows panel, Windows
> does a first request to CUPS through the proxy, and receives back a
>     '401 Unauthorized'
> response, with a challenge for the authentication.
> At this point, unfortunately, Windows <b>stops using the proxy</b>
> and sends the next request directly to the server without going
> through the proxy. As a result, the printer is not accessed
> because there isn't a direct path to the server.
>
> A similar problem occurs if the response is '426' (e.g.
> because CUPS' default is to always use encryption when passing
> authentication info): the initial request goes through the
> proxy, then upon the 401/426 response windows XP stops using
> the proxy and goes directly to the server.
>
> I don't think that this problem can be solved on the CUPS side,
> but wonder if is there anyone else who experienced the same issue,
> and maybe (I know this is not the forum to ask) whether there is
> a Microsoft patch that fixes this.
> If not, I think it is worthwhile mentioning the problem on
> the CUPS notes.
>

I used CUPS at home with 5 clients(3 Windows XP, 1 Windows 98, 1 Vista)
and I don't seem to have the issue you're experiencing. My CUPS server
is running under FC5 with CUPS 1.2 installed.

All of the clients goes through my proxy server all of which requires
basic authentication(PAM module).

I may not understand your problem correctly but just for verification,
I can access my CUPS server web interface through any of my clients via
proxy server.

Check your host files. Do some ping test, etc. Access the CUPS server's
web interface locally(not through proxy) to check configuration is set
correctly.

Good luck.