Find out if programs are connecting to the Internet

Martin Brinkmann
Jan 14, 2013
Updated • Jan 14, 2013

Depending on how you have set up your system, all, some or only select applications and programs may connect to the Internet or local network resources. Especially the "allow all" approach runs the risk that programs establish an Internet connection that you may not want to do so if you'd know about it.

I revealed yesterday how Firefox add-ons may transfer data to servers without your knowledge and was asked to write a guide about how to detect these connections. While you could check the log of your firewall to find out about that, or configure your firewall to block all outgoing connections but those that you allow, it may sometimes be easier to use third party tools that provide you with a quick overview of what's going on at that time on your system.

I'd like to review two programs for that purpose, and link to a third that I have reviewed in 2008.


CurrPorts by Nirsoft is a free portable program for 32-bit and 64-bit versions of Windows that can display all open ports on the system when it is run or refreshed. It is not a real-time scanner, only a program that displays all open ports and connections at the time the system was scanned by it.

All you have to do is download, unpack and run it on your system to get a listing of all processes, their connections, ports and servers they are connected to.

currport software

You can click on the refresh button to run a new scan any time you want to. This may be useful if you have started a program after you ran CurrPort and want the program to scan its connections as well.

You can drag and drop table headers in the program. I have moved the remote host and remote address information to the left for instance as they provide me with direct information about remote servers processes are connected to. You can also sort the listing with a click on a column header-

Check out our detailed review of CurrPorts here, and if you are looking for an alternative, try Close The Door instead. There you also find download links listed.

NetBalancer Free

The second program is a real-time monitor of traffic on a Windows system. The free version of NetBalancer is sufficient for monitoring all processes and their connections. Once you have started the program on the PC you will a list of processes at the top, their current upload and download bandwidth, and the overall upload and download bandwidth they have used.

If you see data listed in the downloaded or uploaded fields you know that the process has made connections. It is a good idea to run the program in the background for some time to get a good reading on all programs you use on a daily basis.

You can click on any process listed here to have its current connections displayed at the bottom right. Here you see all remote IP addresses and protocols it has established connections to.

Block Processes from making connections

If you have identified a process using one of the tools that established connections even though it should not have done so, you have a couple of options to resolve the issue. The first option is to uninstall the program from the system. Maybe there is an alternative available that is not connecting to servers when its run.

You can naturally also try and block all outgoing traffic of the program. This can sometimes render the program useless, so keep that in mind. You can use NetBalancer free for that too, but the free version is limited to three processes only. An alternative would be to configure your firewall to block outgoing connections for selected processes.

If you are using Windows Firewall, you may find Windows Firewall Notifier useful as it displays connection attempts to you giving you the chance to evaluate them and either block or allow the connection afterwards.


Tutorials & Tips

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  1. ilev said on August 4, 2012 at 7:53 pm

    Doesn’t Windows 8 know that www. or http:// are passe ?

    1. Martin Brinkmann said on August 4, 2012 at 7:57 pm

      Well it is a bit difficulty to distinguish between domains and files for instance.

    2. Leonidas Burton said on September 4, 2023 at 4:51 am

      I know a service made by google that is similar to Google bookmarks.

  2. VioletMoon said on August 16, 2023 at 5:26 pm

    @Ashwin–Thankful you delighted my comment; who knows how many “gamers” would have disagreed!

  3. Karl said on August 17, 2023 at 10:36 pm


    The comments section under this very article (3 comments) is identical to the comments section found under the following article:

    Not sure what the issue is, but have seen this issue under some other articles recently but did not report it back then.

  4. Anonymous said on August 25, 2023 at 11:44 am

    Omg a badge!!!
    Some tangible reward lmao.

    It sucks that redditors are going to love the fuck out of it too.

  5. Scroogled said on August 25, 2023 at 10:57 pm

    With the cloud, there is no such thing as unlimited storage or privacy. Stop relying on these tech scums. Purchase your own hardware and develop your own solutions.

    1. lollmaoeven said on August 27, 2023 at 6:24 am

      This is a certified reddit cringe moment. Hilarious how the article’s author tries to dress it up like it’s anything more than a png for doing the reddit corporation’s moderation work for free (or for bribes from companies and political groups)

  6. El Duderino said on August 25, 2023 at 11:14 pm

    Almost al unlmited services have a real limit.

    And this comment is written on the dropbox article from August 25, 2023.

  7. John G. said on August 26, 2023 at 1:29 am

    First comment > @ilev said on August 4, 2012 at 7:53 pm

    For the God’s sake, fix the comments soon please! :[

  8. Kalmly said on August 26, 2023 at 4:42 pm

    Yes. Please. Fix the comments.

  9. Kim Schmidt said on September 3, 2023 at 3:42 pm

    With Google Chrome, it’s only been 1,500 for some time now.

    Anyone who wants to force me in such a way into buying something that I can get elsewhere for free will certainly never see a single dime from my side. I don’t even know how stupid their marketing department is to impose these limits on users instead of offering a valuable product to the paying faction. But they don’t. Even if you pay, you get something that is also available for free elsewhere.

    The algorithm has also become less and less savvy in terms of e.g. English/German translations. It used to be that the bot could sort of sense what you were trying to say and put it into different colloquialisms, which was even fun because it was like, “I know what you’re trying to say here, how about…” Now it’s in parts too stupid to translate the simplest sentences correctly, and the suggestions it makes are at times as moronic as those made by Google Translations.

    If this is a deep-learning AI that learns from users’ translations and the phrases they choose most often – which, by the way, is a valuable, moneys worthwhile contribution of every free user to this project: They invest their time and texts, thereby providing the necessary data for the AI to do the thing as nicely as they brag about it in the first place – alas, the more unprofessional users discovered the translator, the worse the language of this deep-learning bot has become, the greater the aggregate of linguistically illiterate users has become, and the worse the language of this deep-learning bot has become, as it now learns the drivel of every Tom, Dick and Harry out there, which is why I now get their Mickey Mouse language as suggestions: the inane language of people who can barely spell the alphabet, it seems.

    And as a thank you for our time and effort in helping them and their AI learn, they’ve lowered the limit from what was once 5,000 to now 1,500…? A big “fuck off” from here for that! Not a brass farthing from me for this attitude and behaviour, not in a hundred years.

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