Does drupal work with SSL proxy? How?

I want to run my drupal site www.example.com 100% encrypted, with the help of my ISP's ssl proxy.

The ssl URL is https://ssl.webpack.de/www.example.com

Surfing around works as it should, but when I try to create content and klick Submit, the URL is
https://ssl.webpack.de/node/101/edit
instead of
https://ssl.webpack.de/www.example.com/node/101/edit
and I get the error message "404 Not Found". Without ssl, everything is ok.

I changed the base url in settings.php without success:
$base_url = 'https://ssl.webpack.de/example.com';

Does anybody know if drupal works with SSL proxy?