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Netstat in a nutshell

Most people who do TCP/IP troubleshooting are familiar with the most common tools, such as Ping,

Pathping, and Tracert. Windows 2000 includes other tools you might find useful for

troubleshooting TCP/IP connections, one of which is Netstat.



Netstat displays protocol statistics and current TCP/IP connections. For example, you might use

Netstat to determine if an application on your computer is communicating with an external service,

such as Microsoft MSN Messenger. Or, to troubleshoot a connection, you might use Netstat to

obtain statistics on ICMP messages generated by Ping. You would open one console and start a

ping, and, in another console, use Netstat to monitor the progress.



Used alone, without options, Netstat displays the current connections, performing a name lookup

and displaying the resulting connections by host name. You can use the -n option to list

connections by IP address rather than host name, which can speed up results in situations where

name resolution is slow or fails. With or without options, Netstat displays not only the remote

host's name or address but also the port for the connection.



Netstat's -s option allows you to view per-protocol statistics for TCP, UDP, ICMP, and IP. To view a

specific protocol, use the -p option. For example, use the following command to view statistics for

ICMP:



netstat -s -p icmp



If you don't specify an interval, Netstat displays the results once. You can direct Netstat to display

running results by specifying the interval. This example displays IP statistics every three seconds:





netstat -s -p ip 3



To cancel Netstat, press [Ctrl]C.



Netstat shouldn't be the only troubleshooting tool in your toolbox, but when used in combination

with Ping, Tracert, Pathping, and other tools, Netstat is valuable for identifying specific protocol

problems. For more information on Netstat, execute the command with the /? option.

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