Privacy

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Privacy concerns with DHCP (DHCP fingerprinting) (self.privacy)

submitted 2 months ago* (last edited 2 months ago) by possiblylinux127 to c/[email protected]

34 comments fedilink hide all child comments

So many people here will go though great lengths to protect themselves from fingerprinting and snooping. However, one thing tends to get overlooked is DHCP and other layer 3 holes. When your device requests an IP it sends over a significant amount of data. DHCP fingerprinting is very similar to browser fingerprinting but unlike the browser there does not seem to be a lot of resources to defend against it. You would need to make changes to the underlying OS components to spoof it.

What are everyone's thoughts on this? Did we miss the obvious?

https://www.arubanetworks.com/vrd/AOSDHCPFPAppNote/wwhelp/wwhimpl/common/html/wwhelp.htm#href=Chap2.html&single=true

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[–] [email protected] 12 points 2 months ago (2 children)

I feel like I'm missing something here...

Who's going to be fingerprinting DHCP messages on your home network?

Outside of that, fingerprinting or tracking any DHCP info would be the least of my concerns. You have 0 control over any data the moment your devices connect to a public network. What use is DHCP info when you can person-in-the middle all the traffic anyway?

And anyway, what info are you concerned about? Having had a VERY quick browse of RFC2131 the worst thing would be "leaking" the device MAC address which can be discovered via several other means anyway

[–] [email protected] 5 points 2 months ago (2 children)

I guess the hostname could be used to defeat MAC randomization if you use public WiFi like hotels, airports and coffee shops. You could probably identify repeat users if you cared enough.

But then your worry should be the security cameras not the WiFi, because that's what's gonna tie you personally to your device connecting.

[–] [email protected] 1 points 2 months ago

Wear a mask and sunglasses so you just blend in.

[–] possiblylinux127 -1 points 2 months ago (1 children)

See the linked page

[–] [email protected] 2 points 2 months ago

You need to say more than that about what your concern is, especially on devices configured for Mac randomization and other privacy features.

Aruba is looking at the dhcp traffic and inferring information about the device. The device is not sending all of this data.

[–] possiblylinux127 1 points 2 months ago (1 children)

You can't easily man in the middle https with encrypted DNS

[–] [email protected] 1 points 2 months ago (1 children)

Why would encrypted DNS help here? HTTP(S) uses IPs

[–] possiblylinux127 1 points 2 months ago

IPs are arbitrary