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Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

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Re: Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

#11

Post by dfc »

nikcub wrote: post #9

Tor being pitched as a one-stop privacy solution like this is going to backfire bad at some point in the future. It is good that they have the warning about cookies, but there are a hell of a lot of other ways you can be identified. You simply shouldn't be using the same machine you use with your real identity with an identity that needs to be anonymous. Even simply things like ntp time sync request can give you away…

Even simply things like ntp time sync request can give you away

I'd really like to hear more about this one.

Murdoch's hot-or-not required a lot more than an ntp sync request and was concerned with identifying hidden services.

Re: Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

#13

Post by CoffeeDregs »

dfc wrote: post #8
CoffeeDregs wrote: post #7

Earlier quoted context omitted.

Agreed, but one can hope, yes? For example, if I could probably kill not-interesting traffic if I could traffic-shape the traffic (e.g. you can't run more than 10kB/s averaged over 60 seconds through my node, which is plenty to browse the web securely but isn't enough to download Star Trek 2.) The question remains: are there ways to manage (not prevent) this issue?

No, I don't hope. If relay operators can "peel back the layers of my onions" and see the traffic the entire security model is out the window. Edit: I just saw your restatement of your question. Check out the bandwidth management features and set your relay to only allow exit traffic to port 443. More info on the bandwidth management can be found here: https://trac.torproject.org/projects/tor/wiki/doc/TorFAQ#Wha...

Thank you. Your suggestion is very helpful. I'll have a gander at that link.

Re: Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

#14

Post by gizmo686 »

dfc wrote: post #8
CoffeeDregs wrote: post #7

Earlier quoted context omitted.

Agreed, but one can hope, yes? For example, if I could probably kill not-interesting traffic if I could traffic-shape the traffic (e.g. you can't run more than 10kB/s averaged over 60 seconds through my node, which is plenty to browse the web securely but isn't enough to download Star Trek 2.) The question remains: are there ways to manage (not prevent) this issue?

No, I don't hope. If relay operators can "peel back the layers of my onions" and see the traffic the entire security model is out the window. Edit: I just saw your restatement of your question. Check out the bandwidth management features and set your relay to only allow exit traffic to port 443. More info on the bandwidth management can be found here: https://trac.torproject.org/projects/tor/wiki/doc/TorFAQ#Wha...

The security model of Tor allows the exit nodes to see all the traffic in 'plaintext' (indeed, the design of Tor requires it). What the security model requires is that the exit nodes not be able to identify who sent the packets originally.

I put "plaintext" in quotes because they can only see what you want to send to the server, which could be encrypted outside of the context of Tor.

Although I think it is illegal to spy on the data you pass as an exit node, a point that is often not said is that by the design of Tor, you are showing some random person the content of all of your requests, which opens up a whole new attack vector for eavesdropping and man-in-the-middle attacks.

Re: Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

#15

Post by nikcub »

dfc wrote: post #11
nikcub wrote: post #9

Tor being pitched as a one-stop privacy solution like this is going to backfire bad at some point in the future. It is good that they have the warning about cookies, but there are a hell of a lot of other ways you can be identified. You simply shouldn't be using the same machine you use with your real identity with an identity that needs to be anonymous. Even simply things like ntp time sync request can give you away…

Even simply things like ntp time sync request can give you away I'd really like to hear more about this one. Murdoch's hot-or-not required a lot more than an ntp sync request and was concerned with identifying hidden services.

The theory is that the frequency of requests, timezone, server being used and time skew (see also[1]) provide enough bits of information to identify a client.

The exit node or ISP could also forge a response and set the clock a unique amount of time out of sync which can later be identified over a non-anon network.

Whonix, the privacy oriented Linux distribution which uses two virtual machines (an isolating proxy and then a client on a private network) disable NTP by default and require the user to sync time out-of-band because of these concerns. There is a section in their docs about NTP[2]

[1] http://www.reddit.com/r/onions/comments/10usgv/clock_skewing...

[2] http://sourceforge.net/p/whonix/wiki/Advanced%20Security%20G...

Re: Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

#17

Post by stuaxo »

synchronise wrote: post #12

Out of curiosity, would there be much point in swapping out Tor for i2p in this sort of setup?

I think this can work, I'm fairly sure I got this working on kurobox (another ARM based computer) - you need to find a java implementation + you're good to go.

Re: Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

#18

Post by dfc »

nikcub wrote: post #15
dfc wrote: post #11

Earlier quoted context omitted.

Even simply things like ntp time sync request can give you away I'd really like to hear more about this one. Murdoch's hot-or-not required a lot more than an ntp sync request and was concerned with identifying hidden services.

The theory is that the frequency of requests, timezone, server being used and time skew (see also[1]) provide enough bits of information to identify a client. The exit node or ISP could also forge a response and set the clock a unique amount of time out of sync which can later be identified over a non-anon network. Whonix, the privacy oriented Linux distribution which uses two virtual machines (an isolating proxy and…

At first glance the first two paragraphs are hand wavy enough that it is pretty clear that you exaggerated when you said "simply ntp synch requests" and things get a lot worse after paying any attention to the details in your post.

Timezones and NTP? NTP does not use time zones so I am not sure what that has to do with anything.

Exit nodes forging ntp responses? That is going to be pretty tough. Last time I checked tor has a tcp fetish and ntp is squarely in the udp camp.

I checked the reddit link. Lets skip over the fact that you said "identify a client" and the reddit link is about hidden services. In order to work it requires that the hidden service serves http, serves http over plain ipv4, and is running on a computer that is also a relay. So that is not "simple" but most importantly it has very little to do with ntp requests.

I'm not going to lie, I stopped reading the whonix documentation after the first three paragraphs and i have pasted them below:

  Don't wonder... To prevent against time zone leaks, the system clock
  inside Whonix was set to UTC. This means it may be a few hours before
  or ahead of your host system clock. Do not change!

  On the host. If you were a user of TorBOX 0.2.1 or below and removed
  NTP, restore it now.

    sudo apt-get install ntpd
Can you see why I stopped reading when I did? It seems like you may have disremembered the details of the "simple ntp synch requests" can give a way a users identity attack.

Re: Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

#19

Post by zokier »

I can understand people already owning the necessary hardware doing this, but buying $95 kit which essentially makes for a lousy WLAN router seems bit odd. Surely it would make more sense to buy purpose-built WLAN router (for $95 you can get quite fancy one), and install Tor on that?

Re: Onion Pi - Make a Raspberry Pi Into a Anonymizing Tor Proxy

#20

Post by malandrew »

This is really cool because if plug-n-play tor devices become cheap enough to be disposable, then I can see people just adding them to open wi-fi networks with bandwidth caps in order to increase the number of tor exit nodes, which is actually pretty low for such a vital service. Last time I checked there were like 800-1000 exit nodes in existence.
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