Backup Exchange with firewall

Hi again,

does anyone know which additional open ports (TCP and/or UDP) are required for backups with the Networker Module for Exchange when backing up an Exchange 2003 Cluster? We are running a firewall between the backup server and the backup clients and opened the ports as requested in the docs. Normal file backup jobs are running with this firewall configuration but exchange does not. Networker gives us thee following error message:

* exchserver:MSEXCH: [4228] 11/22/06 11:11:25 nsrxchsv_ese.exe Version: 4.1.0.148 Supporting Exchange 2000 and Exchange 2003
* exchserver:MSEXCH: [4228] 11/22/06 11:11:25 System Version: 5.2 Build 3790 Service Pack 1
* exchserver:MSEXCH: [4228] 11/22/06 11:11:25 ESEBCLI2.DLL Version: 6.5.7638.1 Service Pack 2
* exchserver:MSEXCH: [4228] 11/22/06 11:11:46 common\apputil(289): Cannot connect to resdb database on
* exchserver:MSEXCH: [4228] 11/22/06 11:11:46 Failed to find NetWorker server version; advanced features are being disabled.
* exchserver:MSEXCH: [4228] 11/22/06 11:12:07 common\apputil(289): Cannot connect to resdb database on
* exchserver:MSEXCH: [4228] 11/22/06 11:12:07 Performing an Exchange save operation; save level is Differential (Legato Backup Level: 1).
* exchserver:MSEXCH: [4228] 11/22/06 11:12:07 Parsing parameters from the command line...
* exchserver:MSEXCH: [4228] 11/22/06 11:12:07 Opening connection to NetWorker Server...
* exchserver:MSEXCH: [4228] 11/22/06 11:12:28 Cannot connect to resdb database on
* exchserver:MSEXCH: [4228] 11/22/06 11:12:28 Backup operation finished with errors. No savetime was sent.
11/22/06 11:12:49 savegrp: exchserver:MSEXCH: failed.

Analyzing firewall logs gives us denied packets from sourceports below 1023 from exchange-server to destination ports in the networker-range(79xx-9xxx) on the backup-server. I cannot find anything related to these ports in the official docs but opening the ports below 1023 allows creating backups. Any hints?