If I was a malware writer, and some days I wonder why I’m not since it’s so easy, the most important function of the malware would be to “phone home”, with the information I had targeted to steal. There’s nothing unusual about this, since much of the malware currently infecting the Internet does just that.
So, keeping that in mind, when I have an issue on one of my home machines, and occasionally I do, the very first thing I check is the state of the ports on that machine. Actually, since I’m involved in Internet security, I monitor my open ports and Internet connections frequently throughout a browsing session.
At first glance you might think port checking is time consuming and not worth the effort. But it is worth the effort, and it’s not time consuming. More to the point, in my view, it is a critical component of the layered defense approach to Internet security that regular readers of this site are familiar with.
I don’t want to shatter any illusions for those of you who believe that the Internet is “free” but, when running a port checker, you might be unpleasantly surprised at the number of ad servers that hold open ports on your machine.
There are a number of free real-time port analyzers available for download and the following is a brief description of each. If you are familiar and comfortable with using the Windows command structure, then you may want to try the command line utility Netstat, which displays protocol statistics and current TCP/IP connections. This utility and the process, are covered later in this article.
Process and Port Analyzer is a real time process, port and network connections analyzer which will allow you to find which processes are using which ports. A good little utility that does what it says it will do.
View currently running processes along with the full path and file which started it
View the active TCP Listeners and the processes using them
View the active TCP and UDP connections along with Process ID
Double click on a process to view the list of DLL’s
Download at: Download.com
CurrPorts (this is the port tool I use daily), allows you to view a list of ports that are currently in use, and the application that is using it. You can close a selected connection and also terminate the process using it. As well, you can export all, or selected items to an HTML or text report. Additional information includes the local port name, local/remote IP address, highlighted status changes and more.
View current active ports and there starting applications
Close selected connections and processes
Save a text/ HTML report
Info on local port name, local/remote IP address, highlighted status changes
Download at: Download.com
Windows XP includes a command line utility which will help you determine if you have Spyware/Botware running on your system. Netstat displays protocol statistics and current TCP/IP connections.
I use this utility as a test, to ensure that the anti-malware tools and Firewall running on my systems are functioning correctly, and that there are no open outgoing connections to the Internet that I am not aware of.
How to use Netstat:
You should close all open programs before you begin the following process, if you are unsure which ports/connections are normally open while you are connected to the Internet. On the other hand, if you are familiar with the ports/connections that are normally open, there is no need to close programs.
There are a number of methods that will take you to a command prompt, but the following works well.
Click Start>Run>type “cmd” – without the quotes>click OK> this will open a command box.
From the command prompt, type Netstat –a (be sure to leave a space), to display all connections and listening ports.
You can obtain additional information by using the following switches.
Type netstat -r to display the contents of the IP routing table, and any persistent routes.
The -n switch tells Netstat not to convert addresses and port numbers to names, which speeds up execution.
The netstat -s option shows all protocol statistics.
The netstat-p option can be used to show statistics for a specific protocol or together with the -s option to show connections only for the protocol specified.
The -e switch displays interface statistics.
Running Netstat occasionally is a prudent move, since it allows you to double check which applications are connecting to the Internet.
If you find there are application connections to the Internet, or open ports, that you are unfamiliar with, a Google search should provide answers.
Steve Gibson’s website, Shields Up, is a terrific source of information where you can test all the ports on your machine as well as testing the efficiency of your Firewall. I recommend that you take the Firewall test; you may be surprised at the results!
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