Do I need to write a module?

["Tony Thompson" <tony.thompson@stone-ware.com>]

I am investigating an option to use netfilter to allow/deny traffic from
the local subnet based on rules/accounting information that is in
another (Java based) system.  I am new to netfilter so, I can someone
offer some suggestions:

1. Is netfilter the right place to hook or should I look at a firewall
that may provide some higher level hooks for authentication and
accounting?

2. If I should hook into netfilter, is it a good idea to call into a
JVM from a netfilter module?

3. I am not sure what kind of control I have when using the userspace
driver but, should I use that in this situation?  Can I use that
directly from Java so I wouldn't have the hassel of calling into a JVM
from a native process?

If anyone can offer any other suggestions or examples, that would be
appreciated.

Thanks.
Tony