Why does my computer send any network data, even if I am not doing anything?

Is it possible that this network traffic includes private data (text documents, images,...), to which I did not consent?


1 Answer 1


I'm going to assume you ask why you see traffic on your machine, even though you don't actively do anything. The reasons for that are that your computer is doing a lot in the background, which is not triggered by any user action. Let me give a few examples:

  • Replies to requests: Your computer receives network requests all the time. A good example for that are ARP requests in your local network. Your computer will receive them, and may respond to them. This is normal behavior and required for your PC to work.
  • OS and Application Updates: Your OS and your Applications will periodically check to see if updates are available. This is not triggered by any actions of yours, but happens periodically.
  • Background Connections: Some applications open various connections to external services as soon as you open them. For example, Chrome and Firefox both try to reach a specific site to see if captive portals are being used, if ISPs behave correctly, etc.

Of course, there are many more reasons why your computer may show traffic, even if you're not "doing anything".

Could these contain private information without my consent?

That depends what you consider private information. For example, Firefox sends requests to fetch http://detectportal.firefox.com/success.txt. An attacker in the same network could listen to this request and detect that you are using Firefox.

As far as your consent goes, it depends on the Terms of Service of each individual application. You would be surprised to what things you consent just by using regular applications.

Could these replies contain personal documents?

Answering a comment, usually no. Of course, if you use a file-sync service such as Google Drive, Dropbox, etc., it is of course possible that personal files will be included in such traffic, but this is by design.

As for other applications, it would be highly unlikely. For example, if you bought a video game from Steam and it would suddenly send copies of all your files to the publisher, such a case would become popular very quickly and would put the developer into hot water (and likely get their game banned from Steam quickly).

  • Thank you! I have honestly asked because I do not know what happens to me that lately I am beginning to have a little more fear than normal. According to your answer, what I have asked, seems normal behavior. With regard to the question of sending information without consent, I refer to one of our files; text documents, images, etc; without having consented. It is a question based on fear that generates the same ignorance xD. I would be grateful if you could explain to me if this is not possible. I am sure it can be very useful for other people too. Nov 4, 2019 at 10:32
  • @Morganmariano I edited my answer to clarify that.
    – MechMK1
    Nov 4, 2019 at 10:37
  • Thank you, thank you, thank you, thank you! This leaves me calmer about my fear. Damn fears that limit our lives, don’t you? (forgiving the expression). Sorry if you don't understand, the google translator ... Nov 4, 2019 at 10:49
  • @Morganmariano I understand that looking at raw traffic without any context can seem like something is wrong.
    – MechMK1
    Nov 4, 2019 at 12:20

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