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Tor Weekly News October 16th, 2013
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Welcome to the sixteenth issue of Tor Weekly News, the weekly newsletter
that covers whatâs happening in the venerable Tor community.
Making hidden services more scalable and harder to locate
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Christopher Baines started a discussionÂ[1] on tor-dev on the scaling
issues affecting the current design of Tor hidden services. Nick
Mathewson later described Christopherâs initial proposal as âsingle
hidden service descriptor, multiple service instances per intro pointâ
along with three other alternatives. Nick and Christopher also teamed up
to produce a set of seven goals that a new hidden service design should
aim for regarding scalability.
Thereâs probably more to discuss regarding which goals are the most
desirable, and which designs are likely to address them, without â as
always â harming anonymity.
George Kadianakis also called for helpÂ[2] concerning âthe guard
enumeration attack that was described by the âTrawling for Tor Hidden
Services: Detection, Measurement, Deanonymizationâ paper (in section
VII)âÂ[3].
The most popular solution so far seems to be enabling a client or hidden
service to reuse some parts of a circuit that cannot be completed
successfully in order to connect to new nodes. This should âconsiderably
slow the attackâÂ[4], but âmight result in unexpected attacksâ as George
puts it.
These problems could benefit from everyoneâs attention. Free to read the
threads in full and offer your insights!
[1]Âhttps://lists.torproject.org/pipermail/tor-dev/2013-October/005556.html
[2]Âhttps://lists.torproject.org/pipermail/tor-dev/2013-October/005621.html
[3]Âhttp://www.ieee-security.org/TC/SP2013/papers/4977a080.pdf
[4]Âhttps://bugs.torproject.org/9001
Detecting malicious exit nodes
------------------------------
Philipp Winter askedÂ[5] for feedback on the technical architecture of
âa Python-based exit relay scanner which should detect malicious and
misbehaving exits.â
Aaron took the opportunity to mention his plansÂ[6] to leverage the work
done as part of OONIÂ[7] to detect network interference. Aaronâs
intention is to âprovide Tor network tests as part of ooni-probeâs
standard set of tests, so that many individuals will measure the Tor
network and automatically publish their results, and so that current and
future network interference tests can be easily adapted to running on
the Tor network.â
Detecting misbehaving exits so they can be flagged âBadExitâÂ[8] by the
operators of the directory authorities is important to make every Tor
user safer. Getting more users to run tests against our many exit nodes
would benefit everyoneÂâ it makes it more likely that bad behavior will
be caught as soon as possible.
[5]Âhttps://lists.torproject.org/pipermail/tor-dev/2013-October/005593.html
[6]Âhttps://lists.torproject.org/pipermail/tor-dev/2013-October/005596.html
[7]Âhttps://ooni.torproject.org/
[8]Âhttps://trac.torproject.org/projects/tor/wiki/doc/badRelays
Hiding location at the hardware level
-------------------------------------
One of Torâs goals is to hide the location of its users, and it does a
reasonably good job of this for Internet connections. But when your
threat model includes an adversary that can monitor which equipment is
connected to a local network, or monitor Wi-Fi network probes received
by many access points, extra precautions must be taken.
Ethernet and Wi-Fi cards ship with a factory-determined hardware address
(also called a MAC address) that can uniquely identify a computer across
networks. Thankfully, most devices allow their hardware address to be
changed by an operating system.
As the Tails live operating system aims to protect the privacy and
anonymity of its users, it has long been suggestedÂ[9] that it should
automatically randomize MAC addresses. Some important progress has been
made, and this week anonym requested commentsÂ[10] on a detailed
analysis of why, when and how Tails should randomize MAC addresses.
In this analysis, anonym describes a Tails user wanting to hide their
geographical movement and not be identified as using Tails, but who also
wants to âavoid alarming the local administrators (imagine a situation
where security guards are sent to investigate an âalien computerâ at
your workplace, or similar)â and âavoid network connection problems due
to MAC address white-listing, hardware or driver issues, or similarâ.
The analysis then tries to understand when MAC address should be
randomized depending on several combinations of locations and devices.
The outcome is that âthis feature is enabled by default, with the
possibility to opt-out.â anonym then delves into user interface and
implementation considerations.
If you are interested in the analysis, or curious about how you could
help with the proposed implementation, be sure to have a look!
[9]Âhttps://labs.riseup.net/code/issues/5421
[10]Âhttps://mailman.boum.org/pipermail/tails-dev/2013-October/003835.html
Tor Help Desk Roundup
---------------------
The Tor project wishes to expand its support channels to text-based
instant messaging as part of the Boisterous OtterÂ[11] project. Lunar
and Colin C. came up with a possible implementationÂ[12] based on the
XMPP protocol, ProsodyÂ[13] for the server side, and ProdromusÂ[14] as
the basis for the web based interface.
This week, multiple people asked if Tor worked well on the Raspberry Pi.
Although the Tor Project does not have any documentation directed
specifically at the Raspberry Pi (yet!), the issue was raised on Torâs
StackExchange pageÂ[15]. Tor relay operators are encouraged to share
their experiences or ask for help on the tor-relays public mailing
listÂ[16].
[11]Âhttps://trac.torproject.org/projects/tor/wiki/org/sponsors/Otter/Boisterous
[12]Âhttps://trac.torproject.org/projects/tor/wiki/org/sponsors/Otter/Boisterous/WebChat
[13]Âhttps://prosody.im/
[14]Âhttp://forge.webpresso.net/projects/prodromus
[15]Âhttp://tor.stackexchange.com/questions/242/how-to-run-tor-on-raspbian-on-the-raspberry-pi
[16]Âhttps://lists.torproject.org/pipermail/tor-relays/
Miscellaneous news
------------------
Ten years ago, on October 8th, 2003, Roger Dingledine announcedÂ[17] the
first release of tor as free software on the or-dev mailing list.
[17]Âhttps://lists.torproject.org/pipermail/tor-dev/2003-October/002185.html
Damian Johnson announcedÂ[18] the release of Stem 1.1.0Â[19]. The new
version of this âPython library for interacting with Torâ adds remote
descriptor fetching, connection resolution and a myriad of small
improvements and fixes.
[18]Âhttps://blog.torproject.org/blog/stem-release-11
[19]Âhttps://stem.torproject.org/change_log.html#version-1-1
Arlo Breault sent out a detailed plan on how Mozilla Instantbird could
be turned into the Tor MessengerÂ[20]. Feedback would be welcome,
especially with regard to sandboxing, auditing, and internationalization
for right-to-left languages.
[20]Âhttps://lists.torproject.org/pipermail/tor-dev/2013-October/005616.html
The Spanish and German version of the Tails website are outdated and may
soon be disabledÂ[21]. Now is a good time to helpÂ[22] if you want to
keep those translations running!
[21]Âhttps://mailman.boum.org/pipermail/tails-dev/2013-October/003879.html
[22]Âhttps://tails.boum.org/contribute/how/translate/
adrelanos announcedÂ[23] the release of Whonix 7, an operating system
âbased on TorÂ[â], Debian GNU/Linux and the principle of security by
isolation.â The new version includes tor 0.2.4, Tor Browser as the
system default browser and a connection wizard, among other changes.
[23]Âhttps://lists.torproject.org/pipermail/tor-talk/2013-October/030593.html
Lunar sent out a report about the Dutch OHM2013 hacker campÂ[24] that
took place in August.
[24]Âhttps://lists.torproject.org/pipermail/tor-reports/2013-October/000363.html
Philipp Winter, Justin Bull and rndm made several improvements to
AtlasÂ[25], the web application for learning more about
currently-running Tor relays. The HSDir flag is now properly
displayedÂ[26], full country names and flags are shown instead of
two-letter codesÂ[27] and itâs now easier to find out how long a relay
has been downÂ[28].
[25]Âhttps://atlas.torproject.org/
[26]Âhttps://bugs.torproject.org/9911
[27]Âhttps://bugs.torproject.org/9914
[28]Âhttps://bugs.torproject.org/9814
ra, one of Torâs former GSoC students, proposed a patchÂ[29] to add a
command to the Tor control protocol asking tor to pick a completely new
set of guards.
[29]Âhttps://bugs.torproject.org/9934
starlight shared some simple shell snippetsÂ[30] that connect to the Tor
control port in order to limit the bandwidth used by a relay while
running backups.
[30]Âhttps://lists.torproject.org/pipermail/tor-talk/2013-October/030607.html
Upcoming events
---------------
Nov 04 | Workshop on Privacy in the Electronic Society
| Berlin, Germany
| http://wpes2013.di.unimi.it/
|
Nov 04-05 | 20th ACM Conference on Computer and Communications Security
| Berlin, Germany
| http://www.sigsac.org/ccs/CCS2013/
This issue of Tor Weekly News has been assembled by Lunar, Matt Pagan,
harmony, dope457, Damian Johnson and Philipp Winter.
Want to continue reading TWN? Please help us create this newsletter.
We still need more volunteers to watch the Tor community and report
important news. Please see the project pageÂ[31], write down your name
and subscribe to the team mailing listÂ[32] if you want to get involved!
[31]Âhttps://trac.torproject.org/projects/tor/wiki/TorWeeklyNews
[32]Âhttps://lists.torproject.org/cgi-bin/mailman/listinfo/news-team
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