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We have a web server (IIS) and a database server (MS SQL 2005) separated by an application proxy / firewall. We want to keep the number of open ports between the two machines at a minimum. Obviously port 1433 (or equivalent) is needed, however, we also need to support MSDTC transactions. The MS advice here suggests port 135 and a range of other ports.

However, there is no guidance regarding the number of ports to keep open. Is one enough? Do I need ten? What determines the number of ports we need open.

Any pointers appreciated!

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up vote 3 down vote accepted

Here are 2 KB articles that both recommend 15-20 ports being opened in the 5000 range. Here is another article that recommends a minimum of 100 ports because other applications that use RPC dynamic port allocation will use the ports as well. A similar question was asked on stack overflow and it looks like that person accepted the minimum 100 answer.

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Thanks! I had searched on StackOverflow but didn't find that question (or the answers). – Peter K. Aug 19 '09 at 18:19

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