If your operating system on your computer is Windows then you have a handy tool to check who is connected to your computer, or check which programs are being accessed. With Netstat or Network Statistics you can see a list of network connections and other network interface statistics. Troubleshooting TCP/IP connection problems is easier with Netstat, because it will enable you to scan mischievous connections through the list of information on client services and communications through the TCP/IP. With all the connections and services running on your computer it will take a long time to identify which ones are problem connections, so learning to interpret the information provided by Netstat will help shorten the time. Netstat has different utility parameters you could use to display the type of information you want like the Ethernet statistics or just addresses and port numbers among others.
- Select Start and click Run. Go to your Start button found on the right most of your taskbar at the bottom of your screen. Selecting it will display the start menu, find the "Run" option and click it.
- Run the command prompt. Once you click the "Run" option on the Start menu a dialogue box will appear. Type cmd in the window and click OK. This will take you to the command prompt window. You'll see a command prompt something similar to this - C:\Documents and Settings\some name>_. In the blank spot where the blinking line is type in "netstat", without the quotation marks of course, so it would look something like this C:\Documents and Settings\some name>netstat then press enter on your keyboard.
- Specify refresh variable. With a refresh variable you will be able to check new connections in a fresh list through the specified refresh rate. At the end of the parameter "netstat", put in a number of seconds to refresh your list. If you choose to have a fresh list every 10 seconds, then your parameter will look like this netstat 10 at the command prompt. If you want to stop it from refreshing just press Ctrl+C.
- Use different netstat parameters. To view different lists you can set the netstat parameter of your choice, just by placing the proper variable at the end of nestat. Putting the variable " -a" with the syntax netstat will look like this: netstat -a 10 with the refresh rate interval at the end. A netstat -a parameter will show you all connections and listening posts, netstat -e will show Ethernet statistics, netstat -n will show addresses and port numbers, netstat -s shows statistics by protocol, to specify a protocol use netstat -p, netstat -r will show you the routing table contents, netstat -o shows active TCP connections with the process ID.
You can combine parameters such as netstat -an to display a unique list that you can use to analyze. Statistics results will be displayed in different columns to help you identify and analyze information. The Proto column will contain the type of protocol either TCP or UDP. Local address will provide the IP address of the computer and port number used in the connection. Foreign address shows the IP address of the remote computer and the port number used in the connection. The state column shows the state of the TCP connection.