AS/2 authentication

I'm searching everywhere but didn't find an answer for this. How can I prevent non configured peers from sending files to a Mendelson AS/2 opensource server? I've learned that anyone can send files that will end up as an error if that partner is nor configured, but this opens the possibility for a very easy DOS attack, filling up the server logs ans so on.
I didn't find an easy way to implement authentication for each partner acting as a server (local station), however as a client, the configuration for HTTP authentication is there and easy to configure. Am I missing something? Is there any "obscured" configuration that I couldn't find?

Thanks for you help.



Not really. Some of the trade partners has dynamic public addresses so a firewall will not work in cases like this. I really don't like to have a server with an "ANY SOURCE" rule on the firewall, but this is a case I must have a setup like this, so the authentication would be a way to achieve a minimum protection.
Thanks for replying!