tor-dev February 2012

tor-dev@lists.torproject.org

26 participants
24 discussions

Tor and DNS
by Linus Nordberg 26 Feb '12

26 Feb '12

Hi, After some interesting discussions irl last week with knowledgeable DNS and security people (hi Jakob) I'd like to hear from people involved with DNS in Tor what current status is and what needs to be done. More specifically, what's the status of ttdnsd and TorDNSd? Are they being used? Any thoughts about having a local validating resolver? I know there's been some discussions (4zm, are you here?) about using libunbound (which could be interesting for DNSSEC support). Did that evolve into anything useful? I'm by no means a DNS expert but would love to see some discussion about this, partly because future IPv6 work will depend on changes to our DNS system. Thanks, Linus

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Windows Alternative of torsocks/tsocks ?
by Catalin Patulea 18 Feb '12

18 Feb '12

[resending after subscribing to list] Hi Fabio, > On 1/22/12 11:28 AM, Roger Dingledine wrote: >> See also TorCap2: http://www.virtualventures.ca/~cat/ >> but I've never succeeded at getting a license statement out of the author. Roger, I'm sorry if I seemed uncooperative when you asked about the licensing terms of TorCap2. I can see a reference to a discussion with you back in 2006, but I no longer have copies of the actual correspondence, so I don't recall what happened. > Can you confirm whether the TorCap2 is licensed under BSD, GPL or other > opensource license? I have released TorCap2 under the LGPL 3.0 (I have updated the readme and included a license.txt in the zip files). You can use TorCap2 as-is in an application of any license. Any modifications to TorCap2 must be published under the LGPL. > at some Tor related Project we would like to use TorCap2 as a part of an > OpenSource Project whose concept is described at > https://piratenpad.de/p/AnonymousWebApplicationFramework . On a technical note, I doubt that TorCap2 is the right approach here. If you can limit yourself to support Python-only applications to start, then a SOCKS client in Python that implements the same interface as the 'socket' module seems like a much cleaner solution to me. This is now platform-independent, less complex (easier to debug), and gives the Python code the *option* between native sockets and Tor-ified sockets, under the same interface. (maybe you want to check connectivity.. or find the hosts's external IP by fetching a URL.. or talk to hosts on the local network.. etc.) Porting existing Python code would be a matter of search-replacing 'socket' with 'torsocket' (or even just 'import torsocket as socket'). Of course, with this design you would leak network traffic if you spawned a separate process, or if you used a Python native library that directly accesses the OS's socket API. But maybe it's good to start with supporting Python-only applications initially, given the complexity of Win32 API hooking.. Just my $0.02.. Catalin

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Unit testing blog posts
by Esteban Manchado Velázquez 18 Feb '12

18 Feb '12

I ended up publishing it in two parts :-) Here are the URLs: http://hcoder.org/2012/02/13/unit-testing-advice-for-seasoned-hackers-12/ http://hcoder.org/2012/02/15/unit-testing-advice-for-seasoned-hackers-22/ Now I'll have a look at the coverage and see what I can do for the unit tests before I move on to Stem/chutney. -- Esteban

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Fwd: Plan of attack for part (c)
by Watson Ladd 17 Feb '12

17 Feb '12

I'm forwarding the following 2 messages about work that I'm thinking about doing to the Tor code to pave the way towards multiple cryptographic methods for route extension. Feel free to comment critically on the proposed design, especially if it impacts areas you are working on or know about. If you have alternative ideas that's also good. Sincerely, Watson Ladd ---------- Forwarded message ---------- From: Robert Ransom <rransom.8774(a)gmail.com> Date: Thu, Feb 16, 2012 at 8:03 PM Subject: Fwd: Plan of attack for part (c) To: Nick Mathewson <nickm(a)torproject.org>, George Kadianakis <desnacked(a)riseup.net> Cc: Watson Ladd <watsonbladd(a)gmail.com> Forwarding to Nick and George (who has looked at the crypto code before), because I'm not going to be able to think about this much today. This sort of discussion should probably be on the tor-dev mailing list. ---------- Forwarded message ---------- From: Watson Ladd <watsonbladd(a)gmail.com> Date: Thu, 16 Feb 2012 13:15:58 -0600 Subject: Plan of attack for part (c) To: "rransom.8774" <rransom.8774(a)gmail.com> Dear Robert, I've come up with the following sketch of a plan to handle the obstacle of crypt_path_t to multiple negotiation methods. It isn't actually the problem. The problem is the crypto_dh_t * dh_handshake_state. I propose defining an enum handshake_methods_t and a handshake_state that looks like typedef struct { enum method; union { crypto_dh_t *dh_handshake; } u; } handshake_state; The extend_info_t structure will need to be modified to point to a list of similar handshake_key structures, probably in the form of a linked list. This involves modifying the functions that allocate extend_info_t's, of which thankfully there are few. Once this is done we can genericize the onion_skin functions by making new functions which essentially consist of a switch statement on the value of method. One unresolved issue is selecting the method to be used when multiple methods are available: I'll probably just take the first handshake_key and complain if it doesn't match what the handshake_state should be when processing the response. Servers are a trickier issue, but if they have a list of handshake_keys we can sort through it to find the key that matches a particular method, and rely on the new CREATE2 cell mechanism to tell us what the method is. Are there requirements for a fix that this idea doesn't meet? Any hard decisions that I've made the wrong call on? And thank you very much for taking the time to help me through working with the tor code. Sincerely, Watson Ladd -- "Those who would give up Essential Liberty to purchase a little Temporary Safety deserve neither Liberty nor Safety." -- Benjamin Franklin

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Talk on flash proxies Feb. 17
by David Fifield 13 Feb '12

13 Feb '12

If anyone is interested in the bay area, I'll be giving a short tech talk on flash proxies 6:30–7:00 PM on February 17. Gates Computer Science building room 104 353 Serra Street Stanford, CA 94305 http://infolab.stanford.edu/pub/keller/gates-map.html David Fifield

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Obfsproxy client for Android
by Nathan Freitas 12 Feb '12

12 Feb '12

Thoughts on attempting to port and ship Obfsproxy client functionality to Android? We have a good number of Iranian users it seems, and I think we can pull it off in a few days, if it isn't insanely complex. Where should we begin? Any details on exactly what was done for the new TBB? +n

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First test "report"
by Esteban Manchado Velázquez 12 Feb '12

12 Feb '12

Hi there, I'm done with the first batch of work on the test side. You have the (rebased just now) work here: https://github.com/emanchado/tor/commits/master. The rest of this e-mail summarises what I've done and explains my plan for further work. The content of the commits -------------------------- I have reviewed the whole test_util.c and made three kinds of changes: 1. Added more tests. Some of them failed, and after checking with other people on IRC the conclusion seems to be that they should pass (ie. they reproduce actual bugs in the code). To keep the test suite from failing, they are inside "#if 0" blocks. So someone should look for "#if 0" inside test_util.c and fix the code that makes those fail. Or maybe I should file bugs for those? 2. In comparison assertions, the general convention seems to be to place the expected value first ("test_eq(0, functioncall(...))" rather than "test_eq(functioncall(...), 0)"). I have modified the assertions not following that convention, so they all look the same. 3. General clean up, small code reorganisations, fix typos and such. Eg, I have turned all the "tt_int_op(a, ==, b)" into "test_eq(a, b)". I was thinking of blogging about what I saw (esp. related to point 1). I think there are valuable lessons to be learned, which will help other people writing tests (both for Tor and outside of Tor). I'm not sure if there's enough content for a blog post, but if I do it after all, should I post the link here? Plan for the future ------------------- As I haven't explored coverage yet, I'll start with that for the code in src/common/ and see what I can do. My gut feeling (without having looked at other parts of the code yet!) is that tackling unit tests for code in src/or/ will be hard for me, and it seems better to explain what kind of things I have done in src/common/ so others, more familiar with that code, can fix/improve the unit tests for src/or/*. In other words, it seems much more effective for me to support someone who knows the code in src/or/*, rather than the other way around. After I'm done with what I think is easy enough for me to do with the unit tests, I'll have a look at Stem (Damian's suggestion) and chutney (Nick's suggestion), and decide what I do next. -- Esteban

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Tor developers: completed translations now in separate directories
by Runa A. Sandvik 09 Feb '12

09 Feb '12

Hi everyone, The latest version of the Transifex client allows users to specify a minimum percentage of completeness for the translations to be accepted by the client (that is, to be downloaded). The translation.git repository now has a _completed branch for each of our translation resources. If you only want to include 100% completed translations in your project, clone the _completed branch for your project from now on. -- Runa A. Sandvik

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Proposal xxx: Safe cookie authentication
by Robert Ransom 07 Feb '12

07 Feb '12

See attached, because GMail would wrap lines if I sent it inline. Robert Ransom

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Parallel Crypto - Library dep.
by David Goulet 03 Feb '12

03 Feb '12

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi everyone, To help the tor project, I'll contribute some of my spare time to improve multithreading for the Tor code base. I've speak a bit with Nick M. and it seems the crypto lib is an important part to begin with. The wiki page (https://trac.torproject.org/projects/tor/wiki/org/projects/Tor/Multithreade…) indicates, basically, that a worker thread pool with a work queue to dispatch crypto events should be the right approach and I do agree. Is it acceptable to link an external library to the project being a dependence? The library I'm thinking about is "liburcu" which stands for user-space RCU (http://lttng.org/urcu). It's a complete set of lockless data structure including wait-free queue which can be very useful for our case. It support a large variety of architecture and works on BSD and Linux. The Linux kernel use RCU mechanism for a lot of internal data structure today so it's quite tested and solid. The question I think is do we want lockless data structure in Tor or it's not and will not be necessary for the type of workload ? (lockless re-sizable hash tables, red-black tree, stack, linked-list (double also) and queue are available as of today). Waiting on your feedback guys, either way, I'll begin implementing parallel crypto largely based on the wiki page (really good ideas there). Thanks a lot! David -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iQEcBAEBAgAGBQJPKET6AAoJEELoaioR9I02OO0H/2lxrvak2ItAdGsXHsyH2dgz U3ePxZUg8Ix5UuZXA/LnP3T7/HBa47mtPMj3hwuz2Wnarf6FulumYA3A9jKsZyxQ tf6azD+G7CbZjjYPbe8XYfOZC6+x58mF7SciM/maLoFQLzCvw7ruBBXu8j0Ghw5Q hcm8RMIa4UyB0szSpMqkt615sYQBgy7hhEkNKqxnfdP4zIqUIK8mJqBING6r7qU+ EhnIT5VNzKG9FZPkYNzXOvzbtH0MegNfePsi6gDYlkjR7gekiT9wYH9n5tFTPQUu 4BwqaaHR/Wk+zfHaQOmz+KC3eefUqcd+XP82mcPTSUDj4mzG1Sio2ZHKX0IeJVw= =r0da -----END PGP SIGNATURE-----

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tor-dev February 2012