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How To Determine Which Program Uses or Blocks Specific Transmission Control Protocol Ports in Windows Server 2003

Support for Windows Server 2003 ended on July 14, 2015

Microsoft ended support for Windows Server 2003 on July 14, 2015. This change has affected your software updates and security options. Learn what this means for you and how to stay protected.

This article was previously published under Q323352
This step-by-step article discusses how to determine which program uses or blocks specific Transmission Control Protocol (TCP) ports.

The Netstat.exe utility has a new switch, the -o switch, that can display the process identifier (ID) that is associated with each connection. This information can be used to determine which process (program) listens on a particular port. For example, the netstat -ano command can produce the following output:
Proto    Local Address    Foreign Address    State        PIDTCP          Listening    888				
If you use Task Manager, you can match the process ID that is listed to a process name (program). With this feature, you can find the specific port that a program currently uses. Because a program already uses this specific port, another program is prevented from using that same port.

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How to Match the Process ID to a Program

To match the process ID to a program, follow these steps:
  1. Press CTRL+ALT+DELETE, and then click Task Manager.
  2. Click the Processes tab.
  3. If you do not have a PID column, click View, click Select Columns, and then click to select the PID (Process Identifier) check box.
  4. Click the column header that is labeled "PID" to sort the process by PIDs. You should be able to easily find the process ID and match it to the program that is listed in Task Manager.
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How to Obtain Additional Information About the Netstat.exe Utility

To obtain additional information about the Netstat.exe utility, follow these steps:
  1. Click Start, and then click Run.
  2. In the Open box, type cmd, and then click OK.
  3. At a command prompt, type netstat /?.
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Article ID: 323352 - Last Review: 12/03/2007 03:17:20 - Revision: 6.4

Microsoft Windows Server 2003, Standard Edition (32-bit x86), Microsoft Windows Server 2003, Enterprise Edition (32-bit x86), Microsoft Windows Server 2003, Enterprise x64 Edition, Microsoft Windows Server 2003, Datacenter Edition (32-bit x86), Microsoft Windows Server 2003, 64-Bit Datacenter Edition, Microsoft Windows Server 2003, Web Edition, Microsoft Windows Small Business Server 2003 Standard Edition, Microsoft Windows Small Business Server 2003 Premium Edition

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