Remote ActiveSync or e-mail w/Exchange (Server Security)
Posted on 2006-06-15
I am running a network of four Exchange 2000 servers in three locations, serving about 80 users. Four or five users in the company are requesting the ability to download e-mail from the exchange server to their portable devices (Smartphones running Windows Mobile 2003 & 5.0)
Obviously, because of network security implications, this is kind of going to be a pain. Up until now, I have dragged my feet about this, doing research and experimenting with different ideas without implenting a final solution, but now some of those users are higher up the ladder and something finally needs to be done.
Here are the solutions (and problems with each) I have looked at so far:
1) Set the Smartphones up to log into the corporate VPN and then ActiveSync as if they were on the local network. This would be the ideal solution, unfortunately, the Window Mobile 5.0 VPN solutions are anything but robust. I have yet to complete a working ActiveSync session. It's hard enough to tunnel between WinXP and the Cisco - doing it from a smartphone is a nightmare. In addition, I understand that some providers block PPTP (1723,GRE) packets.
2) Port forwarding 143 on the corporate firewalls to the Exchange servers, and forcing users to use IMAP e-mail access on the smartphones. This is probably the most workable solution I have so far, but it doesn't allow access to the rest of their Outlook (Calendar, etc), and it's also cumbersome to access any folder other than the Inbox (You have to manually tell it to sync each one) I'm not totally excited about leaving the IMAP server open to attack on the 'net, but you have to do what you have to do.
3) Set up an isolated Exchange server in a DMZ that is accessible from the internet, and can communicate only to other Exchange servers. This should work reasonably well, but still leaves the network pretty wide open (Especially since the server needs to access AS, etc. from the others) - I'm really only willing to do this as a last resort.
Maybe I'm making this more difficult than it ought to be, but I'm looking for a solution that from the users perspective is robust and easy to use, and from my perspective leaves the network safe and secure.
Full points will be awarded to anyone who has something similar to (1) working.
I'm also open to thoughts on (2) and (3), and any other workable solutions anyone may have.