But you don't have a service uploading it along with the URLs you visit, which is the creepy part. The ID itself can be useful for your own administration. And if such a service were to appear, it could easily be removed. Everything in Linux is optional, especially as long as you stick to open source.

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ranger_danger 40 minutes ago | parent [-]

How do we know? Does anyone check for things like this?

Many, many apps read /etc/machine-id if you do a quick github search.

Apps may have been silently correlating our activity for years without us knowing.

We know DHCP, EFI, GNOME, popularity-contest and many other apps already use it. There are countless ways it could be used already that are hard to detect.

	▲	cyphar 18 minutes ago \| parent [-]
		It should be noted that the "correct" usage of /etc/machine-id is that you use it in a way that doesn't allow cross-correlation between different applications by using a HMAC of the machine-id with an application-specific UUID instead of using it directly. systemd-id128 has a command line flag to do this for you. Whether everyone does that correctly, that's a different question. On the other hand, while developers should be more careful about how they use identifiers like this, if an application on your machine wants to track you they don't need /etc/machine-id.