- tor-dev - lists.torproject.org

Torsocks compile errors
by grarpamp 30 Dec '14

30 Dec '14

On gcc 4.2.1 freebsd 8 (thus not really expecting a fix)... commit ab81544478eb9a0db821fd33684cc2f6aac88c7c syscall.c:213: warning: implicit declaration of function 'handle_mmap' syscall.c:283: warning: cast from pointer to integer of different size ../../src/lib/.libs/libtorsocks.so: undefined reference to `handle_mmap' *** Error code 1

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Hidden service policies
by Mike Hearn 30 Dec '14

30 Dec '14

Hello, As we know, hidden services can be useful for all kinds of legitimate things (Pond's usage is particularly interesting), however they do also sometimes get used by botnets and other problematic things. Tor provides exit policies to let exit relay operators restrict traffic they consider to be unwanted or abusive. In this way a kind of international group consensus emerges about what is and is not acceptable usage of Tor. For instance, SMTP out is widely restricted. Has there been any discussion of implementing similar controls for hidden services, where relays would refuse to act as introduction points for hidden services that match certain criteria e.g. have a particular key, or whose key appears in a list downloaded occasionally via Tor itself. In this way relay operators could avoid their resources being used for establishing communication with botnet CnC servers. Obviously such a scheme would require a protocol and client upgrade to avoid nodes building circuits to relays that then refuse to introduce. The downside is additional complexity. The upside is potentially recruiting new relay operators.

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ScrambleSuit's replay protection incomplete
by Philipp Winter 28 Dec '14

28 Dec '14

In short: The implementation of ScrambleSuit's replay protection is incomplete which means that an active adversary can circumvent it. All the credit for this discovery goes to Lasse Øverlier. ScrambleSuit uses Uniform Diffie-Hellman as one of its authentication mechanisms. To defend against replay attacks, a sever caches the HMAC of a client's authentication message. The attack works as follows. In the first step, an active adversary (e.g., a censor trying to detect ScrambleSuit) observes a client authenticate successfully towards a ScrambleSuit server and captures the server's Uniform Diffie-Hellman response. In the second step, the adversary replays the captured response to the very same server. Since the server did not cache the HMAC of its own response, it will interpret the replayed data as legitimate authentication message of a new client and respond with an authentication response. The adversary now successfully tricked the server into responding despite not knowing the shared secret. This creates a noteworthy distinguisher which can help identifying ScrambleSuit. Luckily, it's easy to fix this problem. Introducing message types would be one option but it would break backwards compatibility. The easiest fix which retains backwards compatibility is to make the server also cache its own HMACs which are part of the response to a client's authentication message. The downside is that it doubles the size of the replay table but that's tolerable. Note that obfs4 is not affected by this problem because a client's and a server's authentication message are different. Cheers, Philipp

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Damian's Status Report - December 2014
by Damian Johnson 28 Dec '14

28 Dec '14

Hi all! Tis that time of year coal appears in all my sox so guess it's time for a status report. This month I set arm aside to polish improvements that accumulated in the Stem 1.3 release... https://blog.torproject.org/blog/stem-release-13 There were a lot of small tweaks, but the highlights for this month were... -------------------------------------------------------------------------------- Hidden Service Tutorial -------------------------------------------------------------------------------- By a bit of serendipity I came across a nice article by Jordan Wright for spinning up hidden services with Stem... https://jordan-wright.github.io/blog/2014/10/06/creating-tor-hidden-service… Federico Ceratto and Patrick O'Doherty have been improving our hidden service support, so I spruced up their contributions and wrote a tutorial of our own that demos it... https://stem.torproject.org/tutorials/over_the_river.html -------------------------------------------------------------------------------- Gentoo Support -------------------------------------------------------------------------------- Thanks to Anthony Basile Stem is now packaged for Gentoo. Installing is as simple as... % emerge stem I've been delighted at how many Gentoo people have jumped out of the woodwork to help. toralf worked with me on ticket #13904 to address testing issues, and Manuel took on Stem 1.3 packaging the same day as its release - thanks guys! -------------------------------------------------------------------------------- Couple other quick things of note is that I updated our OpenHub repository listing so it includes most of our newer projects... https://www.openhub.net/p/tor ... and trimmed membership of our internal lists. Cheers! -Damian

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Drop or merge the projects wiki?
by Damian Johnson 24 Dec '14

24 Dec '14

Hi all. Quick question, any objections to us dropping the projects wiki? https://trac.torproject.org/projects/tor/wiki/org/projects It's years out of date and redundant with the volunteer page, which I continue to update on occasion... https://www.torproject.org/getinvolved/volunteer.html.en#Projects I'm asking here in case there's any strong objections, or folks want us to keep something from it. Cheers! -Damian

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Stem Release 1.3
by Damian Johnson 23 Dec '14

23 Dec '14

Greetings wonderful people of the world! After months down in the engine room I'm delighted to announce the 1.3.0 release of Stem. For those who aren't familiar with it, Stem is a Python library for interacting with Tor. With it you can script against your relay, descriptor data, or even write applications similar to arm and Vidalia. https://stem.torproject.org/ So what's new in this release? ------------------------------------------------------------------------------ Better Hidden Service Support ------------------------------------------------------------------------------ Now it's easier than ever to spin up hidden services! Thanks to contributions from Federico Ceratto and Patrick O'Doherty we now have a set of methods specifically for working with hidden services. Check it out in our new tutorial... https://stem.torproject.org/tutorials/over_the_river.html ------------------------------------------------------------------------------ Faster Descriptor Parsing ------------------------------------------------------------------------------ This release dramatically improves the speed at which Stem can parse decriptors. Thanks to optimizations from Nick Mathewson and Ossi Herrala we can now read descriptors 40% faster! ------------------------------------------------------------------------------ This is just the tip of the iceberg. For a full rundown on the myriad of improvements and fixes in this release see... https://stem.torproject.org/change_log.html#version-1-3 Cheers! -Damian

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Thinking of raising bandwidth stats interval from 15 minutes to 4 hours
by Nick Mathewson 22 Dec '14

22 Dec '14

See https://trac.torproject.org/projects/tor/ticket/13988 . Karsten suggests that I should announce this on tor-dev before merging/deploying it, and he's probably right. Will this break anything you know about? -- Nick

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Tor dev IRC meetings for the rest of this month
by Nick Mathewson 22 Dec '14

22 Dec '14

Hi, all! The regular tor patch workshop will happen on schedule, at 1800 UTC on the #tor-dev IRC channel on Tuesday the 23nd and the Tuesday 29th. I'm also planning to do a Tor dev meeting at the regular time of 1330 UTC on Wednesday the 24th and Wednesday the 31st, though of course it's likely that some folks won't make it at one of those times. (I strongly encourage taking Christmas Eve or New Years eve off, if that's your kind of thing.) Best wishes & happy holidays, -- Nick

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Reminder for weekly OONI dev meeting Monday 2014-12-22 18:00 UTC (19:00 CET)
by Arturo Filastò 22 Dec '14

22 Dec '14

Hello Oonitarians, This is a reminder that today there will be the weekly OONI meeting. It will happen as usual on the #ooni channel on irc.oftc.net at 18:00 UTC (19:00 CET, 13:00 EST, 10:00 PST). Everybody is welcome to join us and bring their questions and feedback. See you later, ~ Arturo

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KIST somewhat implemented
by Nick Mathewson 20 Dec '14

20 Dec '14

Hi! So, Rob came up with this clever way to use help from an OS kernel to improve Tor's performance: http://www.robgjansen.com/publications/kist-sec2014.pdf I've got a sketchy implementation together now. See my comments on the end of ticket 12890. I have a branch which I believe implements something like the KIST algorithm for Linux as I discussed with Rob. I made a list of not-yet-implemented issues. Rob, could you please let me know which of the issues I listed need to be fixed before this is reasonably testable? cheers, -- Nick

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