tor-dev August 2012

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46 participants
42 discussions

[GSoC] [Stegotorus] Pencil down
by vmon 23 Aug '12

23 Aug '12

Hey Zack, I just did my last pushes before putting my pencil down for the final evaluations. They take care of the followings: - The remaining of all your comments on the github. Except for "always use xalloc instead of new". I have used new extensively for instantiating objects. What's exactly about xalloc that's better than new, if you have overloaded both of them? - Documenting the http_apache steg protocol. The tl_oneway_c2s fails the http-proxy test. It still have problem with one-sided EOF. It used to pass when I allow the one way socket shutdown in the http proxy. So, I think stegotorus still have problem with EOF management. You might want to look at it when you have time. Happy moving! vmon

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Tor and NAT devices: increasing bridge & relay reachability or, enabling the use of NAT-PMP and UPnP by default.
by Jacob Appelbaum 22 Aug '12

22 Aug '12

Hi, My latest tech report is now up. I think it would be a nice idea if we could kick off a discussion about Tor, NAT devices and reachability. Tor and NAT devices: increasing bridge & relay reachability or, enabling the use of NAT-PMP and UPnP by default: https://research.torproject.org/techreports/tor-nat-plan-2012-08-22.pdf Feedback welcome and encouraged! All the best, Jake

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[ooniprobe-dev] Summary of OONI hackfest
by Arturo Filastò 22 Aug '12

22 Aug '12

We had a mini hackfest at noisebridge on OONI and this thread is to summarize what we discussed. mct: feel free to add things from your notes that are not detailed here. One of the problems that we mostly focused our attention on was how to detect censorship on HTTP when the user is presented with a block page. The reason for focusing on this is that censorship over HTTP is the most prevalent form. # Detecting censorship in web sites Detecting that the presented web page is not the expected site, but is a censorship page turns out to be a non trivial task, especially when you are dealing with web pages that have dynamic content. This problem is detailed in this trac ticket: https://trac.torproject.org/projects/tor/ticket/6180. We ended up dividing the possible approaches into two macro categories: Statistical and Heuristic [1] One of the properties we would like our classifier to have is that that a user should be able to detect that the presented page is the block page by just having a copy of OONI and some data that can be given to them over a non censored channel (sneakernet for example). ## DOMClass, a eigenvalue based statistical classifier What we ended up implementing is a classifier that considers the DOM structure of the web page. We can easily build such a database of the DOM structure features of the websites we are interested in analyzing and ship these to users. This is how the algorithm works: This classifier uses the DOM structure of a website to determine how similar the two sites are. The procedure we use is the following: * First we parse all the DOM tree of the web page and we build a list of TAG parent child relationships (ex. <html><a></a><c></c></html> => (html, a), (a, b), (html, c)). * We then use this information to build a matrix (M) where m[i][j] = P(of transitioning from tag[i] to tag[j]). If tag[i] does not exists P() = 0. Note: M is a square matrix that is number_of_tags wide. * We then calculate the eigenvectors (v_i) and eigenvalues (e) of M. * The corelation between page A and B is given via this formula: correlation = dot_product(e_A, e_B), where e_A and e_B are resepectively the eigenvalues for the probability matrix A and the probability matrix B. You will note that the Matrix we are computing eigenvalues for somewhat resembles a Markov model for transitions between DOM element X to Y. This algorithm appears to work pretty well even on highly dynamic web sites (such as the homepage of news.google.com). Problems with this algorithm: * It does not take into account the global position of DOM elements or how deeply nested they are. (<a><a></a></a> (a,b),(b,a),(a,b) is equivalent to <a><a></a></a><a></a> (a,b), (b,a), (a,b)) Looking into other possible solutions to this problem I took a look at algorithms that are used to compute graph similarity. This problem could be solved by using an algorithm that calculates the maximum isomorphic subgraph, but this problem is NP-hard. [2] I am unsure if the computation effort to use algorithms along these lines is worth while. I can't seem to find the notes on the rest of the discussion, perhaps mct will integrate with this discussion. - Art. [1] https://trac.torproject.org/projects/tor/ticket/6180#comment:3 [2] <http://en.wikipedia.org/wiki/Subgraph_isomorphism_problem>http://en.wikipedia.org/wiki/Maximum_common_subgraph_isomorphism_problem

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[GSoC] APAF Report
by Michele Orrù 21 Aug '12

21 Aug '12

Hello, As Daniel suggested, I'm writing this email to keep you updated on my Google Summer of Code Project - APAF. Following the hackathon of the 18-21 May, we reached a working build environment, and a primitive administration page. Below follows a brief update about what is the current status of the software: Development: I've defined what a service really is in terms of implementation, and approached the administration service (the "panel") in such a way that any future application may hide or completely override it. This shall give not only a comfortable user experience but also elasticity to the software. Testing: unittests cover most of the software, but even though APAF is still in an embrional state, I would be glad anyway to receive some feedbacks from you, about which OS the apaf was tested on and any bug you were able to find. Documentation: currently is disorganized, and splitted between sphynx and github wiki. But, the data is there, and I promise that on the next days I will merge/rewrite the two :) Anyway, the code is highly documented, in my opinion the generated sphynx documentation is acceptable. Deployment: I kept working on the build system, which at the current revision works on windows, osx and as vanilla python .egg., but there are still some issues - for example, the automation of .deb build and blobbing external tools on windows. In case you need a quick link to the project, https://github.com/mmaker/apaf -- ù

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IRC meeting to plan sponsor L milestones on Wed July 18, 15:00 UTC in #tor-dev
by Karsten Loesing 15 Aug '12

15 Aug '12

Hi everyone, we have an upcoming sponsor contract starting on October 1, 2012 and running until August 31, 2013. To be precise, this contract is not signed yet, but it's very likely to happen. The general deliverables are already defined, but we can suggest which parts we plan to have done by which milestone. The deliverables can be found here: https://trac.torproject.org/projects/tor/wiki/org/sponsors/SponsorL I suggest we have an IRC meeting with all developers who'll be involved in this contract. Deliverables are, of course, not yet assigned to developers. Here are the people who probably should be at the meeting (with most relevant deliverable numbers in parentheses): - Aaron (4) - Erinn (9, 10) - George (1, 2, 3) - Jake (10) - Karsten (2) - Mike (8) - Nick (3) - Runa (5, 6, 7) - Sebastian (9) - Tomas (9) The meeting will happen July 18, 15:00--17:00 UTC in #tor-dev. The main goal of the meeting is to decide on good milestones for December 31, March 31, June 30, and August 31 that will go into the contract. If somebody cannot make the meeting, please talk to me about their possible deliverables before or shortly after the meeting. (If too many people cannot make the meeting, we may reschedule it, but for the moment, let's aim for the date written above.) Thanks, Karsten

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My RSA-PM client-server
by Daniel Dennis 14 Aug '12

14 Aug '12

Last month I posted a message titled "Encrypted PM site/hidden service" inquiring about websites or services that allow users to write messages. I got a few interesting replies but none did exactly what I wanted. So I wrote up this code and put it on github. The major things to note are - Supports Windows and Linux (likely mac as well) - Written in C# .NET - Has a mono and non mono (plain windows) build - Is written in mind to NEVER TRUST THE SERVER - Client has the contents (re-)encrypted in a local database I spent some time ensuring it works perfectly. I was able to reach the server when it was behind a hidden service, I ran client and server on linux and windows. Everything worked as expected. https://github.com/sdjfjsdfiuhszduh/RSA-PM I don't want to host anything myself. It would be nice if someone could so whistle blowers could talk to others securely. If anyone goes through the code let me know what you think. Although I wrote it quickly so it may be confusing to others. -- http://www.fastmail.fm - IMAP accessible web-mail

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Pyonionoo
by Norman Danner 14 Aug '12

14 Aug '12

Hi Karsten, We have a preliminary version of the Pyonionoo front-end at git://github.com/meganchang/pyonionoo.git Make sure to look at the database branch. We'd be happy to hear feedback. Unfortunately, this isn't as far as we wanted to be. A run-down of the main open issues: * We ran into issues with getting sqlite in-memory databases to play nicely with multiple threads (stop-gap solution: use an on-disk database). * Right now it just has the summary handler, though adding the other handlers probably isn't a problem (probably a bit of minor refactoring). * The search GET parameter isn't implemented yet, in part because we realized that implementing it as specified in the protocol isn't so straightforward, at least in SQLite (which does not, in an obvious way, support searching for initial substrings). - Norman -- Norman Danner - ndanner(a)wesleyan.edu - http://ndanner.web.wesleyan.edu Department of Mathematics and Computer Science - Wesleyan University

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TBB Gentoo ebuild
by Alessandro Di Federico 14 Aug '12

14 Aug '12

Hi, I'm trying to put up an ebuild for the Tor Browser Bundle for Gentoo. As you may know an ebuild is a script which automates the build of a certain application. We already have something in Portage [2] (the official ebuild repository) but it's in an experimental state and we want to make sure that it's something useful and not harmful. So I'd like to know your opinion about the idea as whole (is it a good idea at all to build by yourself the TBB instead of using the official one?) and what could be the main problems arising in such an operation. So: 1. Can you name a list of tools to fingerprint a browser so we can compare our ebuild with the official TBB? 2. Which version should we use? We were planning to offer both the current official release (even if TBB for Linux is currently in beta) and something more recent, even if AFAIK this would be for testing purpose only and could weaken anonymity and untrackability. 3. We plan to use the system version of the Tor client, in my understanding it should not be a problem to use a Tor client with a version different from the one officially released, but I could be wrong. We also plan to exclude vidalia (and the "0015-Make-Tor-Browser-exit-when-not-launched-from-Vidalia.patch" patch). 4. We have a different ebuild for the Firefox profile directory (so if it's not installed the HTTPS Everywhere plugin won't be installed), is this a good idea or would it be better to integrate them? 5. Gentoo build system offers USE flags, which are options that allow to customize the way the package is built. These are the USE flag available for the standard Firefox ebuild in Gentoo, which is the base for our build of the TBB: 1. alsa: Adds support for media-libs/alsa-lib (Advanced Linux Sound Architecture) 2. bindist: Disable official Firefox branding (icons, name) which are not binary-redistributable according to upstream. 3. custom-cflags: Build with user-specified CFLAGS (unsupported) 4. custom-optimization: Fine-tune custom compiler optimizations, setting this is not recommended. 5. dbus: Enable dbus support for anything that needs it (gpsd, gnomemeeting, etc) 6. debug: Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see http://www.gentoo.org/proj/en/qa/backtraces.xml 7. ipc: Use inter-process communication between tabs and plugins. Allows for greater stability in case of plugin crashes 8. libnotify: Enable desktop notification support 9. minimal: Prevent sdk and headers from being installed 10. pgo: Add support for profile-guided optimization using gcc-4.5, for faster binaries. This option will double the compile time. 11. startup-notification: Enable application startup event feedback mechanism 12. system-sqlite: Use the system-wide dev-db/sqlite installation with secure-delete enabled 13. webm: Use system media-libs/libvpx for HTML5 WebM video support. 14. wifi: Enable wireless network functions Looking at the TBB build script this the combination of USE flags to make as similar as possible to the official release (minus means the USE flag is disabled): -pgo -debug -bindist -custom-optimization -crashreporter webm ipc system-sqlite -wifi. I'm planning to remove the possibility to configure these use flags. Do you agree? For further details you can take a look at the ebuild [1], which should be understandable. Take a look also at the current ebuild for TBB [2]. Is there something else we should pay attention to in the build process or in general? Thanks in advance, Alessandro Di Federico [1] http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/www-client/firefox/… http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/eclass/mozconfig-3.… [2] http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/www-client/torbrows…

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[GSoC] [Stegotorus] update
by vmonmoonshine＠gmail.com 13 Aug '12

13 Aug '12

Hello Tor-devers, In last two weeks I was busy implementing the protocol by which the st server sends a url dictionary to the client, so they the client can communicate with server using this url code. It was bit tricky because chop needed to be involved to distinguished between the data being serve to the user and the data for the steg module. This is working now. I also made the curl st client to st server communication non-blocking and now curl sharing the socket with libevent (for the reply). The curl communication with apache server (for providing covers) is still blocking. This is not critical as long as the cover webserver and st server are on the same machine, but is a good feature to think about. You can get everything here: https://github.com/zackw/stegotorus/tree/f--payload-servers But you need to have apache installed on the server and run payload_scraper first: https://github.com/vmon/payload_scraper then copy the generated payload list into apcahe_payload/server_list.txt The name of steg protocol is http_apache (instead of http) The next 10 days will be writing unit tests, testing, and writing documentation for http_steg protocol. Cheers, vmon

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Fwd: [tor-relays] tcmalloc in FreeBSD
by Jordi Espasa Clofent 11 Aug '12

11 Aug '12

Hi, I posted this message in tor-relays, but it seems to me (and another people) that dev mail-list is better channel to use. Thanks! -------- Original Message -------- Hi all, From time to time my tor node (minibofh) stopped to work properly; since it's a tiny FreeBSD VPS, the root origin was some CPU over-consumption. I'm taking some actions to fix it (more swap, freeing CPU from another services... etc). The FreeBSD tor port offers to you the tcmalloc compilation option, so I had some fun reading this interesting paper: http://goog-perftools.sourceforge.net/doc/tcmalloc.html I recompiled the tor port but just using the tcmalloc option. Actually, now I got the google-perftool package and, obviously, the tcmalloc library: mb# pkg_info | grep google google-perftools-1.8.3 Fast, multi-threaded malloc() and nifty performance analysi mb# pkg_info -L google-perftools-1.8.3 | grep malloc.so /usr/local/lib/libtcmalloc.so /usr/local/lib/libtcmalloc.so.2 But, when I'm checking which libraries the tor binary is using, I get: mb# ldd /usr/local/bin/tor /usr/local/bin/tor: libz.so.5 => /lib/libz.so.5 (0x281aa000) libm.so.5 => /lib/libm.so.5 (0x281bc000) libevent-2.0.so.6 => /usr/local/lib/event2/libevent-2.0.so.6 (0x2844e000) libssl.so.7 => /usr/local/lib/libssl.so.7 (0x28489000) libcrypto.so.7 => /usr/local/lib/libcrypto.so.7 (0x284d7000) libthr.so.3 => /lib/libthr.so.3 (0x281df000) libc.so.7 => /lib/libc.so.7 (0x28090000) So... I understand that the tor binary is actually NOT using the new tcmalloc library. Am I wrong? PS. I adding a CC to tor FreeBSD port mantainer.

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tor-dev August 2012