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
How to Match the Process ID to a Program
To match the process ID to a program, follow these steps:
- Press CTRL+ALT+DELETE, and then click Task Manager.
- Click the Processes tab.
- If you do not have a PID column, click View, click Select Columns, and then click to select the PID (Process
Identifier) check box.
- 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:
- Click Start, and then click Run.
- In the Open box, type cmd, and then click OK.
- At a command prompt, type netstat
Article ID: 323352 - Last Review: December 3, 2007 - Revision: 6.4
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- Microsoft Windows Server 2003, 64-Bit Datacenter Edition
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