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

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Article ID: 323352 - View products that this article applies to.
This article was previously published under Q323352
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SUMMARY

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        PID
TCP      0.0.0.0:80       0.0.0.0:0          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.

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.

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 /?.

Properties

Article ID: 323352 - Last Review: December 3, 2007 - Revision: 6.4
APPLIES TO
  • 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
Keywords: 
kbhowtomaster kbnetwork KB323352

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