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Discussion => Security => Topic started by: Ro-Jaws on April 21, 2013, 07:58 pm

Title: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 21, 2013, 07:58 pm
I've been thinking about using it for a while now but since I last checked they have integrated( it into TAILS (I think its as simple as adding an obfsproxy bridge to vidalia).
The problem is I use a live Liberte which I am very at home with. Is it worth switching to TAILS? I always thought it was bloated (I have yet to come across the situation that requires ultra-secure anonymous power-point presentations) but is the additional security worth it? I've never been able to find anything that shows TAILS as being less secure than Liberte but I'm happy to be corrected on that.
I have no idea whether my ISP is doing DPI but there is no reason to (not that its stopped them before!) and while I have no interest in making LE's job any easier it would be nice to know how much actual use this would be as opposed to simply making me feel better.
Title: Re: Obfspoxy - Is it worth it?
Post by: Duffman on April 21, 2013, 08:13 pm
If you can't be bothered to make the switch, then using a VPN will also mask the fact that you're using tor to your ISP. Using tor isn't incriminating though but it's always nice to have those extra safeguards, even if it's only for your own peace of mind. ;)
Title: Re: Obfspoxy - Is it worth it?
Post by: astor on April 21, 2013, 08:48 pm
If anything, Tails is probably more secure. We know Liberte doesn't work with obfsproxy bridges by default. Does it do stream isolation? Does it scramble RAM on shut down?

Does it have any security vulnerabilities?

Tails is officially supported by the Tor Project and has a lot more users, a lot more people auditing it, and gets regular updates. Last point release for Tails was 12 days ago. Last release of Liberte was in September.
Title: Re: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 21, 2013, 09:14 pm
Thanks guys for the quick responses.

Astor- I don't know about the other issues but I do know liberte scrambles and erases RAM on shutdown (also on removal of the live USB I think). I believe there was some debate about how much (or little) the midori browser was identifiable but that was almost a year ago and in any case the browser is epiphany now.
My final problem is tails is the fact that it DOES update so often :p I always use a live CD due to excessive paranoia about wear-levelling issues with USB so when it changes every 2 months it uses a lot of my DVDs! However I am aware that buying a couple more DVDs is preferable to spending time with LE in my house.

Duffman - appreciate your thrusting in the direction of the problem. I have been toying with a VPN for some time but I struggle with the logging issues.

Any ideas on combining the 2? would that make them redundant? If I use a obsfproxy bridge is that not itself revealing, they are publicly available no? Like standard bridges am I opening myself to observation by a compromised bridge?
Title: Re: Obfspoxy - Is it worth it?
Post by: Duffman on April 21, 2013, 09:21 pm
You could indeed combine the two, which would hide your actual IP address from a compromised bridge.
However it does somewhat defeat the point of obfuscating your tor usage, unless you want to hide it from your VPN provider as well.
As far as logging goes, most VPN providers will claim they don't but there's really no way to be sure.
On the other hand if you're planning on only using it for tor browsing then even if they're logging everything, it will all be encrypted.
Title: Re: Obfspoxy - Is it worth it?
Post by: astor on April 21, 2013, 09:24 pm
I believe there was some debate about how much (or little) the midori browser was identifiable but that was almost a year ago and in any case the browser is epiphany now.

That's another problem. How well is Epiphany patched against various potential security issues and anonymity leaks? The vanilla TorBrowser should be the most secure for the same reasons listed above, and Tails uses it instead of rolling its own torified web browser, plus it comes out often enough to always have the latest or next to latest TBB.

My final problem is tails is the fact that it DOES update so often :p I always use a live CD due to excessive paranoia about wear-levelling issues with USB so when it changes every 2 months it uses a lot of my DVDs! However I am aware that buying a couple more DVDs is preferable to spending time with LE in my house.

A stack of 50 DVDs is like $30. So if your freedom isn't worth 60 cents every month...  :)

Title: Re: Obfspoxy - Is it worth it?
Post by: tree on April 21, 2013, 10:07 pm
On the other hand if you're planning on only using it for tor browsing then even if they're logging everything, it will all be encrypted.
Wouldn't your VPN provider see everything you're doing on tor since it's the one connecting to tor or am I missing something here?
Title: Re: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 21, 2013, 10:10 pm
As far as I know there are no leaks with epiphany but this is based purely on other people's evaluation as I lack the knowledge to evaluate it myself.

I think the case for tails (even without obfsproxy) has been made.

It sounds like the VPN might be a little overkill, though it might be useful stopping a comprimised bridge tracking my ip...except that I use a standard TBB on my non-secured computer for things I dont care that much about (the occasional torrent mostly) so in any case there will be verifiable tor usage from the ip.

Well I feel I am starting to get close to a secure set-up at least.

Thanks for the help astor and Duffman, really appreciate it.
Title: Re: Obfspoxy - Is it worth it?
Post by: Duffman on April 21, 2013, 10:21 pm
On the other hand if you're planning on only using it for tor browsing then even if they're logging everything, it will all be encrypted.
Wouldn't your VPN provider see everything you're doing on tor since it's the one connecting to tor or am I missing something here?
They would just see encrypted packets, they would see you connecting to tor but not what you're doing as tor encrypts all your communication.
It sounds like the VPN might be a little overkill, though it might be useful stopping a comprimised bridge tracking my ip...except that I use a standard TBB on my non-secured computer for things I dont care that much about (the occasional torrent mostly) so in any case there will be verifiable tor usage from the ip.
I hope you're not suggesting that you use tor to torrent large files? :P
In which case I definitely recommend a VPN instead, tor is already slow enough. ;)
Title: Re: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 21, 2013, 10:26 pm
what sort of cad do you take me for? I'm no reprobate! :p In actuality I like to think I am a little more responsible than that, tor is to get the torrent file! after that its clearnet all the way
Title: Re: Obfspoxy - Is it worth it?
Post by: Duffman on April 21, 2013, 10:45 pm
what sort of cad do you take me for? I'm no reprobate! :p In actuality I like to think I am a little more responsible than that, tor is to get the torrent file! after that its clearnet all the way
Haha that's what I thought but I needed to be sure.. ;D
In that case you wouldn't really need tor though and you could just use the VPN for that.
Title: Re: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 21, 2013, 11:07 pm
what sort of cad do you take me for? I'm no reprobate! :p In actuality I like to think I am a little more responsible than that, tor is to get the torrent file! after that its clearnet all the way
Haha that's what I thought but I needed to be sure.. ;D
In that case you wouldn't really need tor though and you could just use the VPN for that.

That's a very good point actually. VPN for torrents hmmm. Unfortunately I need tor for the torrents as pirate bay is blocked here (not sure if it the ISP or the country or what) and that is too good a source to miss. There is still the logging issue but it would certianly make me less obvious, though I like to think at approx 4 downloads a month with another 2 that are entirely legal I'm not too high on the watch list - famous last words......
Title: Re: Obfspoxy - Is it worth it?
Post by: Duffman on April 21, 2013, 11:17 pm
what sort of cad do you take me for? I'm no reprobate! :p In actuality I like to think I am a little more responsible than that, tor is to get the torrent file! after that its clearnet all the way
Haha that's what I thought but I needed to be sure.. ;D
In that case you wouldn't really need tor though and you could just use the VPN for that.

That's a very good point actually. VPN for torrents hmmm. Unfortunately I need tor for the torrents as pirate bay is blocked here (not sure if it the ISP or the country or what) and that is too good a source to miss. There is still the logging issue but it would certianly make me less obvious, though I like to think at approx 4 downloads a month with another 2 that are entirely legal I'm not too high on the watch list - famous last words......
Actually using a VPN would circumvent the blocking of TPB as well, I prefer kat.ph though. :P
Also changing your DNS server would probably already be sufficient to visit the site again.
I don't think you really have to worry though over some tor traffic and a few torrents.
Title: Re: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 22, 2013, 01:27 am
How ironic if I end up being busted for file sharing :p

In other news the switch over to tails was very very very easy. If anything it tries a little to hard to hold my hand at every stage (while oddly having the usual excessive degree of complexity of linux systems just below the user friendly service).
All that pales into nothing in comparison to the ease of setting up obfsproxy bridges which is so easy I was certain I had done it wrong but I can see no issues in the log. A word of warning though - obfsproxy bridges seem very...flighty, I got 5 to start with and the log shows a change from one about 20 minutes after starting use of them (though this could well be an intentional changing of bridges).
Title: Re: Obfspoxy - Is it worth it?
Post by: astor on April 22, 2013, 02:07 am
In other news the switch over to tails was very very very easy. If anything it tries a little to hard to hold my hand at every stage (while oddly having the usual excessive degree of complexity of linux systems just below the user friendly service). All that pales into nothing in comparison to the ease of setting up obfsproxy bridges which is so easy I was certain I had done it wrong but I can see no issues in the log.

Glad it worked out for you! :)

A word of warning though - obfsproxy bridges seem very...flighty, I got 5 to start with and the log shows a change from one about 20 minutes after starting use of them (though this could well be an intentional changing of bridges).

What do you mean by "change from one"?

But yeah, bridges can go down quickly. The first time I tried to use the obfsproxy protocol, I got two bridges and neither of them worked. I thought maybe I had misconfigured something, but after requesting two new bridges, it worked. Best thing is to have a few extras on hand.
Title: Re: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 22, 2013, 02:25 am
My apologies! That was some god-awful phrasing on my part.

I did not get 5 bridges at all. I got 2 bridges and withing 20 minutes the 1st had failed and within 30 the 3rd had gone and the whole thing ground to a halt. I then put 5 fresh ones in and have been running on them since without any trouble.

Should I be making a note of bridges? or is it better to use fresh ones each time I log in?
Title: Re: Obfspoxy - Is it worth it?
Post by: astor on April 22, 2013, 02:34 am
You should stick with as few bridges as possible. Assuming that some are run by our adversaries, the more bridges you "sample", the more likely you are to get on someone's list.

Bridges are supposed to be for censored users in places like China and Iran. No western countries block access to Tor, so you gotta figure that local bridge users will be interesting to LE in these countries. Trying to hide their Tor use, they must be up to no good.

So it's entirely possible that they are running some bridges and enumerating the IP addresses that connect to them. To mitigate that attack, connect to as few as possible.
Title: Re: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 22, 2013, 03:00 am
Thanks astor - going to make a note of that.

Am I correct in thinking in this case a VPN would be useful as a further barrier between me and any malicious bridges?
Now this is drifting off topic a little would it be of any use to move to running tor in a VM or with a live version of tails would that be entirely redundant?
Oh that reminds me, I was looking through some old posts on the topics of bridges (they look to have been before obfsproxy) and it was recommended to set up your own private bridge to avoid that scenario of having your IP harvested by a compromised bridge. This seems eminently sensible to me but would using another computer of mine accessing the net through the same access point do the job. I think it would if my understanding of the bridges is correct but every time I think I have a grip on the infrastructure of tor I read something and it slips from my fingers.

Title: Re: Obfspoxy - Is it worth it?
Post by: astor on April 22, 2013, 03:36 am
Am I correct in thinking in this case a VPN would be useful as a further barrier between me and any malicious bridges?
Now this is drifting off topic a little would it be of any use to move to running tor in a VM or with a live version of tails would that be entirely redundant?

People have different opinions about this. I also think most people don't understand how to be anonymous, but maybe I'm wrong and they are right. Here's my opinion, anyway.

Unless you are a high value target -- unless your adversary is actively looking for you, and they know you use Tor, so that can be used as circumstantial evidence against you -- you're better off using Tor like everyone else, and looking like everyone else. You're better off mixing into the crowd. As such, there are 500K daily Tor users (connecting to regular relays) and only 30K daily bridge users. Even fewer of those bridge users are going through VPNs or doing other complicated things to hide their Tor use. If you are not an existing target, but you don't want to be picked out of a fishing expedition, then you should act like everyone else. Use regular relays. Sure, somebody could see that you are using Tor, but so what? So are millions of other people. It's the ones who are taking extra precautions to hide that will stick out to our adversaries.

And no, I don't think a VPN will protect you, because legal businesses rarely fight LE demands for data. And all this stuff about VPNs that don't log? Yeah, that's a promise that can be revoked (thanks to an LE demand) at any time without your knowledge. The whole point of the Tor design is that you don't trust any entity that can see your whole circuit. That's privacy by design, rather than privacy by policy.

Oh that reminds me, I was looking through some old posts on the topics of bridges (they look to have been before obfsproxy) and it was recommended to set up your own private bridge to avoid that scenario of having your IP harvested by a compromised bridge. This seems eminently sensible to me but would using another computer of mine accessing the net through the same access point do the job. I think it would if my understanding of the bridges is correct but every time I think I have a grip on the infrastructure of tor I read something and it slips from my fingers.

No that's bad, because then your "bridge" or entry point is effectively the middle hop in your circuit.
Title: Re: Obfspoxy - Is it worth it?
Post by: astor on April 22, 2013, 04:58 am
Let me give you another example. A few weeks ago, I was talking to someone online who was using the ExcludeNodes feature to exclude all relays in his country and several other countries that host some of the biggest relays. He was having trouble connecting to sites, especially hidden services. Well, what do you expect when you tell your Tor client to ignore half the network?

I understood the logic behind what he was doing, but also why he was wrong. He believed that it was easier for LE in his country to watch domestic relays and potentially identify him. He also believed that LE in those other countries were more likely to be watching their relays.

I pointed out to him why excluding huge swaths of nodes was a bad idea. Imagine one of your entry guards is malicious, and the operator is watching all the IP addresses that connect to it, and the relays that they connect to on the other side. If he sees a Tor client in country X that never connects to relays in country X, that's very suspicious. By changing the default Tor behavior, you make yourself stick out. You want to look like everyone else.

He thought about that for a minute and replied, "Like a school of finish."

Exactly. Walk up to a pond and pick a fish. Come back an hour later and see if you can find the same fish. Unless it has marks that make it stick out, you won't be able to do it.

The safest behavior is the default behavior, 1. because the Tor Project people know more about anonymity than we do and pick those defaults for a reason, and 2. because most people stick with the defaults. Once you start doing uncommon, exotic, and complicated things, you make yourself more identifiable, but more importantly, you draw attention to yourself.
Title: Re: Obfspoxy - Is it worth it?
Post by: blowmanthesnowman on April 22, 2013, 05:00 am
Am I correct in thinking in this case a VPN would be useful as a further barrier between me and any malicious bridges?
Now this is drifting off topic a little would it be of any use to move to running tor in a VM or with a live version of tails would that be entirely redundant?

People have different opinions about this. I also think most people don't understand how to be anonymous, but maybe I'm wrong and they are right. Here's my opinion, anyway.


Unless you are a high value target -- unless your adversary is actively looking for you, and they know you use Tor, so that can be used as circumstantial evidence against you -- you're better off using Tor like everyone else, and looking like everyone else. You're better off mixing into the crowd. As such, there are 500K daily Tor users (connecting to regular relays) and only 30K daily bridge users. Even fewer of those bridge users are going through VPNs or doing other complicated things to hide their Tor use. If you are not an existing target, but you don't want to be picked out of a fishing expedition, then you should act like everyone else. Use regular relays. Sure, somebody could see that you are using Tor, but so what? So are millions of other people. It's the ones who are taking extra precautions to hide that will stick out to our adversaries.

And no, I don't think a VPN will protect you, because legal businesses rarely fight LE demands for data. And all this stuff about VPNs that don't log? Yeah, that's a promise that can be revoked (thanks to an LE demand) at any time without your knowledge. The whole point of the Tor design is that you don't trust any entity that can see your whole circuit. That's privacy by design, rather than privacy by policy.

Oh that reminds me, I was looking through some old posts on the topics of bridges (they look to have been before obfsproxy) and it was recommended to set up your own private bridge to avoid that scenario of having your IP harvested by a compromised bridge. This seems eminently sensible to me but would using another computer of mine accessing the net through the same access point do the job. I think it would if my understanding of the bridges is correct but every time I think I have a grip on the infrastructure of tor I read something and it slips from my fingers.

No that's bad, because then your "bridge" or entry point is effectively the middle hop in your circuit.


What if you set up your own bridge on a cloud computing server such as amazon's as opposed to a computer at your house? Would that make it less risky? And is it possible to set up your own private obfs bridge?
Title: Re: Obfspoxy - Is it worth it?
Post by: astor on April 22, 2013, 05:07 am
Sure, you can put it on Amazon or any VPS.
Title: Re: Obfspoxy - Is it worth it?
Post by: Ro-Jaws on April 22, 2013, 11:27 am
Thanks astor, this has been a real learning experience for me. I would +1 you if I could.

My only query with what you say is...how do you know if you are being watched? I am well aware that I am very unlikely to be of any interest to anyone with the resources to deploy against me that would require the use of obfsproxy ect. Actually I think I can answer my own question - there are certain actions that need to be done to catch LEs attention, as I am of no interest in other areas of my life I think my best bet would be anonymity by hiding in the crowd.
Tails has spoilt me though, not going back to liberte.....