Firewalls and SQLNet

[ividal <ividal_(_at_)_mecon_(_dot_)_ar>]

Hello:
Maybe this subject is not in the right place (sure it's not) but I think
some of you can have some information.
I need an aplication proxy for sqlnet connections through a firewall:
somebody knows a non commercial proxy (in the fwtk style) for testing it? 
(I got some 1995-papers from Oracle, and it seems not as easy as a plug
proxy or similars)
Any point/opinion/word will be very appreciated
Thank you all
Greets

Ignacio