Integrating Exim with Microsoft Exchange
Advanced routing and security for vulnerable hosts

Speaker

Jason Meers, Mediavest    eximmv-online.co.uk

Outline

The paper discusses a method for removing the risks associated with presenting Microsoft Exchange directly to the Internet. It addresses issues for administrators who must use Exchange in a corporate environment, but have concerns over its ability to protect the valuable resources it holds, or its ability to provide advanced routing and filtering of messages before delivery.

The tutorial shows a real-life example of Exim in use as an SMTP gateway to an internal Exchange server, providing a level of separation from internet based enumeration tactics and exploits.

The tutorial provides a mechanism for:

• Proving temporary redirection by Domain.
• Providing permanent redirection by email address.
• Restricting the domains allowed for relay and delivery.
• Restricting IP addresses allowed for relay and delivery.
• Sending and receiving mail via a dedicated appliance or third party Virus/Spam/Porn scanning service such as Messagelabs.