I have a strange problem in a customer. He connects their laptops over IPSec into the corporate LAN and the firewall/VPN server assigns IP addresses from the IPSec Address Pool (different from LAN subnet). There are some Packet Filter rules on the firewall that allow traffic from this IPSec Pool into the LAN, and especifically into their Exchange box for mail and NetBIOS.
That's working fine so far, and he can browse the LAN, can ping servers (incl the Exchange box) and can access everything via IP and name. However, when he tries to retrieve mail from the Exchange mailbox using Outlook over the VPN, it times out... I must point out that OWA works fine.
I tail the firewall & VPN logs while he's trying to connect and **absolutely nothing** (relevant to this problem, of course) shows being blocked.
Before you ask, we have also tried disabling the XP personal firewall as well as the IPSec client's own firewall without success (or obviously I wouldn't be asking here :-)
Exchange 2003 on Windows 2003 Server
Outlook 2003 on XP Pro SP2
Firewall/VPN is a Linux-based appliance (Astaro Security Linux)
The IPSec client is NCP's Secure Entry Client (www.ncp.de)
I am totally puzzled by this problem, and as I'm due to visit them next Thursday if you could throw in some pointers before then, I would be grateful.