[Zope] Proxy setting for Zope and Products

Hello all, I'm responsible of a server (Debian Sarge) which has been put behind a firewall! I am strugling with proxy problems. For instance, CMFSin doesn't seem to work (for syndication slots in Plone), and LDAPUserFolder cannot reach an external ldap server. On the system itself, I have set the http_proxy environment variable (in .bashrc), it works fine for apt-get, for example, but it seems it has no effect on Zope! Do you have any idea if there is a way to inform directly Zope and all its products about a proxy in a simple way, or only products that are proxy-aware can be set to work in such an environment? Thanks in advance! serge