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The risks of putting the email server in the DMZ

Currently our internal email server is located on a computer behind the firewall like everything else. Our database administrator has asked that I move our email server to the DMZ so that the database can link with the email system. Apparently, the functionality he wants will only work if the email server is in the DMZ. Is there a particular risk in doing this, and if so, how can I eliminate or reduce the risk?

Anytime you put a corporate system open to the Internet there is a risk involved. However, if you build the system...

properly you can reduce the risk. Start by using two network adapters. One for the DMZ and the other for internal access. Make sure you set up port filtering on the networks cards and only let traffic that is needed through. If you can move Web mail off your mail server and onto another server this will also help (keeping IIS out of the DMZ). Thoroughly check all NTFS permission for security vulnerabilities. For example, replace the "Everyone Group" with "Authenticated Users" wherever possible. As, always make sure you system is up-to-date with patches.

This was last published in August 2003

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