There are two options to configure your AS2 service. The first one is an HTTP forwarding from the DMZ server to the internal server, i.e. without an AS2 service on the DMZ server. The second possibility is the one known for the FTP service. The data will in most cases be sent from the internal system.

Forwarding from the DMZ Server

This will make sure that your communication partner gets a direct response if the internal system is not available. If you choose that option, make sure to open the HTTP port (default is 80) between the DMZ server and the internal server.

The following entries have to be added in file ./etc forward.properties on your DMZ server.

/partner/AS2Retrieve=http://internerserver/partner/AS2Retrieve
/partner/AS2Retrieve/*=http://internerserver/partner/AS2Retrieve

Send AS2 Messages via Dynamically Assigned Alternative DMZ

See section Sending via Dynamically Assigned Alternative DMZ.