File /etc/machine-id

figueroa · Posted: Mon Mar 11, 2019 3:06 am Post subject: File /etc/machine-id

Discussion referenced in the news at Distrowatch:
https://distrowatch.com/weekly.php?issue=20190311#news
references a file /etc/machine-id being discussed by Devuan team.

I have that file, the same one since 18 November 2017, readable by anybody. Isn't this a security risk for snooping software? It's like I've been fingerprinted. I don't want such a file. Is anybody doing anything about this? I don't run systemd.
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Andy Figueroa
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amd64/23.0/split-usr/desktop (stable), OpenRC, -systemd -pulseaudio -uefi

Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

You can delete it at shutdown if you want, dbus will recreate it with a different value at the next boot.

If you're worried about snooping software, don't install any.

bunder · Bodhisattva Joined: 10 Apr 2004 Posts: 5934

zfs uses something similar, /etc/hostid... but it's based off your ip address, and if you're using 192.168.x.x, there's nothing to be worried about there because its really not identifying.

it looks like you can also define them both on the kernel line, so you could always change them up every few weeks as well.
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figueroa · Posted: Mon Mar 11, 2019 3:41 am Post subject:

figueroa · Posted: Mon Mar 11, 2019 3:44 am Post subject:

bunder · Bodhisattva Joined: 10 Apr 2004 Posts: 5934

figueroa · Posted: Mon Mar 11, 2019 4:02 am Post subject:

Hu · Moderator Joined: 06 Mar 2007 Posts: 21607

Rather than deleting it, wouldn't it be better to patch the offending program(s) not to create it? That would be better than assuming you will reboot often enough to clear it routinely. Failing that, patch them to store it somewhere that is automatically cleared, like /run or a directory under management of a tmpreaper.

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

Seems dbus really wants it.

eccerr0r · Posted: Tue Mar 12, 2019 3:43 am Post subject:

If you're running systemd/journald, the machine id is used to select which directory the logs go to.
There's a lot more things you can get from the machine that uniquely identifies it (ifconfig doesn't need root and can get your MAC address for one), though one more is not good. Any one tried making this file unreadable to the world?
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Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

arnvidr · l33t Joined: 19 Aug 2004 Posts: 629 Location: Oslo, Norway

Perfect is the enemy of good, so that's a whole lot of irrelevant points you're making.

And fingerprinted by dbus, obviously. Still not adequately explained why this id is necessary.

I added a rm to the dbus init script shutdown routine, since it is responsible for re-creating it at boot-time anyway. I found some references to others having the file on a tmpfs, which would accomplish the same thing. It's a reasonable compromise until an explanation is found for *why* it is bad to change it while the system is running.
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eccerr0r · Posted: Tue Mar 12, 2019 4:21 pm Post subject:

krinn · Watchman Joined: 02 May 2003 Posts: 7470

oh so that ultra secure machineid is protect and to use it i must do
sd_id1000000010101000243000_get_machine_app_specific_ultra_secure_cryptic() {
cat /etc/machine-id
}

that's their vision of security?

figueroa · Posted: Tue Mar 12, 2019 5:32 pm Post subject:

figueroa · Posted: Tue Mar 12, 2019 5:45 pm Post subject:

mike155 · Posted: Tue Mar 12, 2019 6:38 pm Post subject:

figueroa · Posted: Tue Mar 12, 2019 6:47 pm Post subject:

eccerr0r · Posted: Tue Mar 12, 2019 7:21 pm Post subject:

I think I'm going to chmod it and see what breaks in userland, they should not be using it, IMHO.

-edit-

Hmm. The data appears to be available in dbus anyway (so it seems anything that talks to dbus has the potential to use it). So we have to trust the applications that we run... surprise surprise...
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Intel Core i7 2700K/Radeon R7 250/24GB DDR3/256GB SSD
What am I supposed watching?

figueroa · Posted: Fri Mar 15, 2019 7:21 pm Post subject:

Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

Where do you get that systemd owns this file from?

figueroa · Posted: Fri Mar 15, 2019 8:30 pm Post subject:

Naib · Posted: Fri Mar 15, 2019 8:48 pm Post subject:

figueroa · Posted: Fri Mar 15, 2019 8:59 pm Post subject:

Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

/etc/init.d/dbus