Jabber::Component::Proxy is a new and experimental Perl library for Jabber that provides a mechanism for selectively allowing access to Jabber components such as JUDs or Conferencing. It attempts to address the problem of a component being either internal (to the Jabber server it's connected to) or world-accessable and nothing inbetween.
The basic idea is that you front the component that you want to protect by another 'proxy' component, one instantiated using Jabber::Component::Proxy. You advertise your 'protected' component using the id of your 'proxy' component, and traffic flows via the proxy which (a) translates addresses on the fly to and from the protected component and (b) allows you to allow or deny packets based on the originating JIDs using a simple XML-based configuration file.
The address translation is done such that there's no need to store any information while packets are being processed by the protected component, making the proxy stateless and very simple. Also, you can modify the access configuration XML while the proxy component is running and send a HUP signal to get it to re-read the configuration.
There's some rudimentary module documentation here.
The first version of Jabber::Component::Proxy, 0.01, can be obtained from your nearest CPAN mirror, or directly.