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[GSoC] Revamp GetTor summary
by ilv 30 Aug '14

30 Aug '14

Hi! First of all, I want to thank the people at tor-dev that make this happen every year, it was an awesome experience and I sincerely hope to be around for a long time. I also want to thank my mentor Sukhbir for always being around to solve doubts and checking up my progress, and to my co-mentor Nima for his always useful advices and comments. Secondly, I would like to give you a brief summary of what I did during this 3-4 months: 1) Rewrote GetTor from scratch. Now it should be easier to add new ways to distribute download links for TBB. 2) Created two components for this new GetTor: SMTP and XMPP. 3) Enabled the (old) multilingual feature. Now you can receive replies in your language (in case translation exists). 4) Created a component to automatically upload TBB to Dropbox. 5) Enabled basic blacklisting of users. It basically prevents flood by specifying a limit of requests during a certain period of time. 6) Added a small SQLite database for 5) and to get some stats. No real info about the addresses/accounts stored. I would really appreciate any feedback on the work done, specially about the points 5) and 6). Do these points make sense to you? The plan for now is to keep doing tests and deploy it asap (hopefully during September). As always, you can check the code on [0]. That would be for now, have a nice weekend! [0] https://github.com/ileiva/gettor/tree/master/src Best, -- 4096R/540BFC0E

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problems building on osx 10.9.4
by Alan Fay 29 Aug '14

29 Aug '14

Hello! I'm trying to get a working build of Tor so I can learn more about working on item "m. Improve test coverage in Tor". Apologies ahead of time for being green; this seemed to be the most accessible place to start contributing...I read through doc/HACKING and I'm slowly working through that. I'm running osx 10.9.4. I ran: $ ./autogen.sh $ ./configure ... checking for libevent directory... configure: WARNING: We found the libraries for libevent, but we could not find the C header files. You may need to install a devel package. configure: error: Missing headers; unable to proceed. I installed libevent-2.0.21-stable from source, and then nickm on #tor-dev helped me see some permissions issues in /usr/local/include/event2 and /usr/local/lib/libevent* ; please see: [ http://0bin.net/paste/fuObUINKL1EOICf8#jJuGjo2wv65-7QNcHLGBcFPsNdAwhRlWmg6O… ] I found reference to this error on the tor-relay mailing list here, but I didn't get far with any of those suggested fixes, and it's also for osx 10.4. This is the first hit when I google the error: [ https://lists.torproject.org/pipermail/tor-relays/2012-January/001192.html] Thanks, Alan

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Catch probability of EE node greater than G and E node
by saurav dahal 29 Aug '14

29 Aug '14

Hello, The following is the default Tor network in shadow simulator: Total BW of Guard flagged nodes=258.15 MB/S Total BW of Middle nodes=23.69 MB/S Total BW of Exit flagged nodes=13.23 MB/S Total BW of Guard+Exit flagged nodes=213.4 MB/S *1st Case:* I inserted 40 guard nodes and 40 exit nodes, each of 5 MB/S in above Tor network and performed the simulation. Following are the bandwidth weights derived from the consensus document of webclient when Guard and Exit nodes of 5MB/S are added separately: Wbd=1454 Wbe=0 Wbg=4882 Wbm=10000 Wdb=10000 Web=10000 Wed=7091 Wee=10000 Weg=7091 Wem=10000 Wgb=10000 Wgd=1454 Wgg=5118 Wgm=5118 Wmb=10000 Wmd=1454 Wme=0 Wmg=4882 Wmm=10000 *2nd Case:* I added 80 Guard-Exit (EE) nodes, each 5MB/S and perform the simulation. Following are the bandwidth weights derived from the consensus document when EE nodes of 5MB/S are added: Wbd=4722 Wbe=0 Wbg=0 Wbm=10000 Wdb=10000 Web=10000 Wed=4826 Wee=10000 Weg=4826 Wem=10000 Wgb=10000 Wgd=452 Wgg=10000 Wgm=10000 Wmb=10000 Wmd=4722 Wme=0 Wmg=0 Wmm=10000 I calculated catch probability i.e., probability that a client chooses my inserted nodes in both guard and exit position, in both cases and found that the 2nd case yields more probability. By examining the above weights, how it is possible that the catch probability for EE nodes are much higher than those of guard and exit node separately? OR is there any other reason for this? Can anybody please explain this? Thanks, -- Saurav

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Bandwidth Weighted Node selection algorithm
by saurav dahal 29 Aug '14

29 Aug '14

Hello, In the paper, "Zhen Ling; Junzhou Luo; Wei Yu; Ming Yang; Xinwen Fu, "Extensive analysis and large-scale empirical evaluation of tor bridge discovery," *INFOCOM, 2012 Proceedings IEEE* , vol., no., pp.2381,2389, 25-30 March 2012", the author has mentioned about Bandwidth Weighted Node selection algorithm. He has mentioned about bandwidth weights WG and WE, responsible for node selection. But in the Tor directory protocol version 3, there is no such mention of these weights but rather there are other weights such as Wgg, Wee, etc. Can anybody please elaborate on this? Thanks, -- Saurav

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Prototype Primitives for Website Traffic Fingerprinting defenses
by Mike Perry 28 Aug '14

28 Aug '14

Hello all, What follows is a summary of the primitives that Marc Juarez aims to implement for his Google Summer of Code project on prototyping defenses for Website Traffic Fingerprinting and follow-on research. After a review of Tamaraw[1], Adaptive Padding[2], CS-BuFLO[3], and the Supersequence[4] work, as well as some discussion at the Tor dev meeting, we came up with this list of padding message primitives. These functions are meant to be sent as command cells from one endpoint to the other. Some are bidirectional commands, others can only be sent in one direction (client to relay, or relay to client). For now, they will be implemented as ad-hoc messages between two modified obfsproxy (called wfpadtools) instances. The source code for this fork lives here for the moment: https://bitbucket.org/mjuarezm/obfsproxy-wfpadtools/ Long term, I am thinking that all of these should be specified as if they were their own RELAY_* cell type from tor-spec.txt: https://gitweb.torproject.org/torspec.git/blob/HEAD:/tor-spec.txt#l1215 This means that padding would be a circuit-level property, and it would be possible to send it to and from any hop in the circuit, due to leaky-pipe topology (using the "recognized" field). In a world of very cheap and excessive middle and Guard node bandwidth, we would run this padding to the middle node. For the wfpadtools prototype, it will obviously only cover the first hop. Here's the list of primitives, broken down by research paper: Generic Messages (common to all defenses): RELAY_IGNORE() Description: Simple fixed-length (CELL_SIZE) padding cell. Direction: Bidirectional (client to relay, relay to client) Parameters: None RELAY_SEND_PADDING(N,t) Description: Send the requested number of padding cells in response. Direction: Client to relay Parameters: N: Number of padding cells to send in response to this cell t: microseconds delay before sending RELAY_APP_HINT(session_id, status) Description: A hint from the application layer for session start/stop Direction: Client to relay Parameters: session_id: A string identifying the session (ie keyed hash of url bar domain) status: "Start" or "Stop", indicating session start and end. Adaptive Padding Messages: RELAY_BURST_HISTOGRAM(histogram[], labels_ms[], remove_toks, fuzz, when) Description: Specifies a histogram that encodes a delay distribution representing the probability of sending a single padding packet after a given delay in response to either an upstream cell, or a client-originating cell. Direction: Client to relay Parameters: histogram[]: Contains delay distribution of sending an IGNORE packet after sending a real packet labels_ms[]: millisecond labels for the bins (with "Infinity"/"Ignore" bin to allow encoding the probability of not sending any padding packet in response to this packet). remove_toks: If true, follow Adaptive Padding token removal rules. If false, histograms are immutable. fuzz: If true, randomize the delay uniformly between bin labels. If false, use bin lables as exact delay values. when: If set to "receive", this histogram governs the probably of sending a padding packet after some delay in response to a packet originating from. If set to "send", this histogram governs padding packets that are transmitted after a packet arrives from upstream (the middle node). In both cases, the padding packet is sent in the direction of the client. RELAY_GAP_HISTOGRAM(histogram[], labels_ms[], remove_toks, fuzz, when) Description: Specifies a histogram that encodes a delay distribution representing the probability of sending a single additional padding packet after a given delay following a padding packet that originated at this hop. Direction: Client to relay Parameters: histogram[]: Contains delay distribution of sending an IGNORE packet after sending an IGNORE packet labels_ms[]: millisecond labels for the bins (with "Infinity"/"Ignore" bin to allow encoding the probability of not sending any padding packet in response to this packet). remove_toks: If true, follow Adaptive Padding token removal rules. If false, histograms are immutable. fuzz: If true, randomize the delay uniformly between bin labels. If false, use bin lables as exact delay values. when: If "receive", this histogram applies to locally-inserted padding packets that were initially sent in response to client-originated data. If "send", this histogram applies to packets sent in response to locally-inserted padding packets sent in response to upstream data. Note that this means that implementations must maintain this metadata as internal state as the system transitions from BURST_HISTOGRAM initiated padding into GAP_HISTOGRAM initiated padding. In both cases, the padding packet is sent in the direction of the client. CS-BuFLO Messages: RELAY_TOTAL_PAD(session_id, t): Description: Requests that endpoint pad all batches to nearest 2^K cells total or until APP_HINT(session_id, stop) Direction: Client to relay Parameters: session_id: The session ID from APP_HINT() t: The number of microseconds to wait between cells to consider them part of the same batch. RELAY_PAYLOAD_PAD(session_id, t, R): XXX: The paper was not clear enough for me to understand this primitive Tamaraw: RELAY_BATCH_PAD(session_id, L, t) Description: Requests that endpoint pad all batches of cells to L cells total or until APP_HINT(session_id, stop) Direction: Client to relay Parameters: session_id: The session ID from APP_HINT() L: The multiple of cells to pad to. t: The number of microseconds to wait between cells to consider them part of the same batch. Comments, questions, and suggestions are welcome! In particular, I'm not sure I got either the CS-Buflo or the tamaraw primitives completely correct. 1. http://cacr.uwaterloo.ca/techreports/2013/cacr2013-30.pdf 2. http://freehaven.net/anonbib/cache/ShWa-Timing06.pdf 3. http://arxiv.org/abs/1401.6022 4. http://cacr.uwaterloo.ca/techreports/2014/cacr2014-05.pdf -- Mike Perry

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Tor Data Leak
by sureyourejoking＠aim.com 28 Aug '14

28 Aug '14

To Whom it May Concern, I recently noticed that Tor Browser was leaking data about websites I visited in Tor to my hard drive. I am running Mac OS X 10.6.8 on a 2010 model Macbook Pro 6,2. I am using TorBrowser Version 3.6.3. The data appears in the directory "/Users/Username/Library/PubSub/Feeds/", where "Username" represents my username. The directory contains xml files with random names and a .xml extension. They contain text and url's from websites which I have only visited using Tor. I use "No-Script" in Tor, and it is active by default. "No-Script" was active when I visited all of the websites, except for youtube, since the videos will not play while "No-Script" is active. I have installed the following add-ons to Tor: "Adblock Edge 2.1.4" and "Privacy Badger Firefox 0.2.1". I noticed these xml files a month ago, and moved the contents of /Users/Username/Library/PubSub/ to a separate location. Since then, I have watched the contents of this directory closely. Two days after I deleted the contents of "PubSub", a directory called "Database" appeared containing a file called "Database.sqlite3". This file seemed not to have any information about websites I visited. A while later, the "Feeds" directory appeared, but was empty. The "Feeds" directory remained empty for about two weeks. Yesterday, xml files appeared in the Feeds directory, which now contains 1.1 MB of files. Is this a security bug in Tor Browser?

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[RELEASE] Torsocks 2.0.0 stable
by David Goulet 26 Aug '14

26 Aug '14

Hi everyone! Following the discussion of bug #10007[1], this is the *stable* release 2.0.0 for torsocks. Nothing major went in since -rc7, see the change log below. 2014-08-11 torsocks 2.0.0 * Fix: compilation issue on Debian kfreebsd-i386 * Fix: add LICENSE file to repository * Fix: add compilation requirements to README.md Again, as usual, and forever! *please* code review, test and most importantly report any issues. Contribution ftw! :) Thanks to everyone! Git: https://gitweb.torproject.org/torsocks.git Tarball: https://people.torproject.org/~dgoulet/torsocks/torsocks-2.0.0.tar.bz2 (sig: https://people.torproject.org/~dgoulet/torsocks/torsocks-2.0.0.tar.bz2.asc) Cheers! David [1] https://trac.torproject.org/projects/tor/ticket/10007

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Call for testing/review: obfsclient-0.0.1
by Yawning Angel 25 Aug '14

25 Aug '14

Hello all, I just tagged the obfsclient v0.0.1 (Release) Download at: https://github.com/Yawning/obfsclient/releases/tag/v0.0.1 Major changes since 0.0.1-rc2: * Invalid padding lengths in obfs3/ScrambleSuit handshakes are now correctly handled. * Handshake timeout is now set to a random interval between 60 and 120 seconds. * The ScrambleSuit probability distributions are now closer to what obfsproxy generates. * "--version" will now cause obfsclient to print the version and exit. * Various code cleanups. Some notes about ScrambleSuit: * I reverted the "workaround" I had for bug #11100, so Session Ticket handshakes to bridges running obfsproxy 0.2.6 will fail if they have been running long enough to trigger the bug condition. * Actual protocol behavior is closer to obfsproxy than my previous releases, but still not identical to 0.2.7. the next obfsproxy release will close the difference further. Hopefully it is of some use to people. Special thanks to Fabian Keil for help testing and fixing the various release candidates. Questions, comments, feedback appreciated as always, -- Yawning Angel

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Damian's Status Report - August 2014
by Damian Johnson 25 Aug '14

25 Aug '14

Hi all, getting my status report out of the way a tad early. Deadlines for my day job at Amazon required working a weekend so April was mostly spent just getting caught up on code reviewing contributions... * Nick Mathewson greatly improved Stem's performance at parsing consensus documents. Thanks Nick! (#12859) * Rewrote Nick Hopper's patch for verifying consensus signatures. I'd really love to merge it, but it needs tests first. (#11045) * Code reviewed federico3's addition of better Controller methods for handling hidden service config options. (#12533) * Fixed stylistic issues cited by the newly released pep8 1.5.7, and also corrected a handful of python 3.x test failures. * Code reviewed a BridgeDB change to take advantage of Stem for isis. (#9380) * GSoC finals are finished! This year had a lower pass rate than we usually do (four of our thirteen students didn't pass), but I don't think there's necessarily any lessons to draw. This concludes my backlog of things I owe other people, so next up I'll finally be getting back to arm development! -Damian

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[GSoC] Consensus diffs - Sixth report
by Daniel Martí 24 Aug '14

24 Aug '14

Hello everyone, This is the sixth and last status report of my Google Summer of Code project, which is to implement consensus diffs for Tor. Two weeks ago I had two main tasks left for the project to get to a minimal functioning state. The first was to figure out a clean way to cache old consensuses on disk. The second was to write the fetching of consensus diffs, and the corresponding serving of consensus diffs via spooling. Both of these were done, and last week I was able to launch a small local network via chutney and finally see consensus diffs be properly generated, served, fetched and applied. The hard pencils down date is tomorrow evening. I want to polish things up a bit and try to find last-minute bugs. Of course there will be quite a bit of work left once GSoC is over to get the outcome of this project included in Tor. Other than that, I'm quite happy with how the project turned out. I intend to continue contributing to Tor, at least to the extent of getting the code merged into master and fixing any bugs that may arise until it is suitable for a stable release. I'll continue pushing my work on Github [1] for now. See the "readme" branch for reference on what the consdiff-N branches mean. Regards. [1] https://github.com/mvdan/tor -- Daniel Martí - mvdan(a)mvdan.cc - http://mvdan.cc/ PGP: A9DA 13CD F7A1 4ACD D3DE E530 F4CA FFDB 4348 041C

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