Configuring DTC Single Port Support
When Microsoft Distributed Transaction Coordinator (MSDTC) starts, it listens on one of the dynamically assigned RPC server ports. If the Windows Firewall is enabled, then you must open all possible ports that RPC can dynamically allocate to DTC. This exposes other services that use dynamic ports to the network. Windows now lets you configure the RPC server port on which the MSDTC listens.
Configuring the MSDTC Server to Use a Specified Port
Beginning in Windows°7, You can configure the MSDTC to use a specific port by setting the HKLM\Software\Microsoft\MSDTC\[ServerTcpPort] registry key to a specified port.