Ports etc. needed for directly calling EJBs over internet

[Thomas Taeger]

Often we have heard the arguments against directly communicating with the EJB tier, but I still can not agree in generally.
Parsing servlet parameters is just ungainly compared to just call EJB methods and passing normal (serializable) parameters.
For me parameter parsing looks like a fallback to pre-Java or to CGI days, and in my experience this way was very instable.
Directly calling EJBs over internet is used for Extranets of big companies, for example to allow employees to enter sold amounts, orders, etc. from their home office. So I tried it myself.
Workstations calling EJB methods over my intranet allready worked fine.
Now I tried to find out what is the minimum needed to enable clients directly calling EJBs over the Internet without tunneling.
In the BinTec-1200 router in front of the Sun J2EE reference server I
- configured the address translation needed (to 192.168.x.x)
- enabled only the following ports:
80 http standard port
9089 Apache Webserver
1050 J2EE server listen port / NamingService
8000 WebService
7000 SecureWebService
9191 WebService
- Must the following port be enabled per default?:
1099 JRMP

I still could not get the connection.
Can you imagine any more ports needed or any other reasons?
Do you know any publicly available literature?
Thank you in advance.
Thomas.