Since there is no mechanism defined to log the user out of a HTTP authenticated session you have to use a workaround. Most browsers forget their login data once they received a 403 response. The problem is, that the user have to return to the normal starting page manually.

Update 2017-02-22: It seems that this technique doesn't work anymore in recent Firefox and Chrome browsers.

Apache's include directive does not accept wildcards, so something like this won't be allowed:

Include /srv/www/vhosts/*/conf/vhost.conf

You can use mod_perl to realize this. Additionally, the following example does a simple permission check to ensure that the included file has not been modified by an ordinary user:

Some tutorials suggest to use the system properties http.proxyUser and http.proxyPassword to get proxy authentication, but that won't work since - in contrast to http.proxyHost and http.proxyPort - these properties will not be processed by Java's HttpURLConnection.

Other suggest to use a custom default Authenticator. But that's dangerous because this would send your password to anybody who asks.