tor-dev September 2016

tor-dev@lists.torproject.org

42 participants
34 discussions

Proposal 247 (Hidden Service Vanguards) Overhaul
by Mike Perry 09 Jun '17

09 Jun '17

I spent some time trying to clean up proposal 247 based on everyone's comments, as well as based on my own thoughts. Please have a look if you commented on the original proposal, and complain if I've not taken your thoughts into account. (Aaron: In particular, I made several tradeoffs in favor of performance and DoS resistance that may be at odds with some of your suggestions, but I think the end result is still OK after looking into the Sybil rates and thinking about the adversary model in more detail. You may disagree). I've attached my updated version of the proposal inline in this mail, but the canonical updated proposal is in my remote at: https://gitweb.torproject.org/user/mikeperry/torspec.git/tree/proposals/247… Here's a summary of the changes (which are also listed in Git): * Try to make a coherent threat model and specify its assumptions * Fold in my comments about using disjoint sets ("buckets") for the third level guard. * Make the parameter discussion subsection its own section, and include tables with far more detail for the Sybil success rates. * Put the rotation period in a separate subsection from the number of guards * Switch to using min(X,X) and max(X,X) for the distribution for the second and third layer guard lifespans, respectively. Add a subsection describing this distribution (3.2.3) * Changed the default parameters based on these tables, and based on my own intuition about Tor's performance properties. * Move the load balancing, torrc, and other performance considerations to their own section (Section 5). * Move "3.2. Distinguishing new HS circuits from normal HS circuits" to section 4.1. * Fold in some of "3.3. Circuit nodes can now be linked to specific hidden services" into 4.1. Some of it I just removed, though, because I did not find it credible. * Added Roger's concerns about guard linkability to Section 4.2. * Added a denial of service subsection to Section 4.3. ================================ Filename: 247-hs-guard-discovery.txt Title: Defending Against Guard Discovery Attacks using Vanguards Author: George Kadianakis Created: 2015-07-10 Status: Draft 0. Motivation A guard discovery attack allow attackers to determine the guard node of a Tor client. The hidden service rendezvous protocol provides an attack vector for a guard discovery attack since anyone can force an HS to construct a 3-hop circuit to a relay (#9001). Following the guard discovery attack with a compromise and/or coercion of the guard node can lead to the deanonymization of a hidden service. 1. Overview This document tries to make the above guard discovery + compromise attack harder to launch. It introduces an optional configuration option which makes the hidden service also pin the second and third hops of its circuits for a longer duration. With this new path selection, we force the adversary to perform a Sybil attack and two compromise attacks before succeeding. This is an improvement over the current state where the Sybil attack is trivial to pull off, and only a single compromise attack is required. With this new path selection, an attacker is forced to do a one or more node compromise attacks before learning the guard node of a hidden service. This increases the uncertainty of the attacker, since compromise attacks are costly and potentially detectable, so an attacker will have to think twice before beginning a chain of node compromise attacks that he might not be able to complete. 1.1. Visuals Here is how a hidden service rendezvous circuit currently looks like: -> middle_1 -> middle_A -> middle_2 -> middle_B -> middle_3 -> middle_C -> middle_4 -> middle_D HS -> guard -> middle_5 -> middle_E -> Rendezvous Point -> middle_6 -> middle_F -> middle_7 -> middle_G -> middle_8 -> middle_H -> ... -> ... -> middle_n -> middle_n this proposal pins the two middles nodes to a much more restricted set, as follows: -> guard_3A_A -> guard_2_A -> guard_3A_B -> guard_3A_C -> Rendezvous Point HS -> guard_1 -> guard_3B_D -> guard_2_B -> guard_3B_E -> guard_3B_F -> Rendezvous Point Note that the third level guards are partitioned into buckets such that they are only used with one specific second-level guard. In this way, we ensure that even if an adversary is able to execute a Sybil attack against the third layer, they only get to learn one of the second-layer Guards, and not all of them. This prevents the adversary from gaining the ability to take their pick of the weakest of the second-level guards for further attack. 2. Design This feature requires the HiddenServiceGuardDiscovery torrc option to be enabled. When a hidden service picks its guard nodes, it also picks two additional sets of middle nodes `second_guard_set` and `third_guard_set` of size NUM_SECOND_GUARDS and NUM_THIRD_GUARDS respectively for each hidden service. These sets are unique to each hidden service created by a single Tor client, and must be kept separate and distinct. When a hidden service needs to establish a circuit to an HSDir, introduction point or a rendezvous point, it uses nodes from `second_guard_set` as the second hop of the circuit and nodes from that second hop's corresponding `third_guard_set` as third hops of the circuit. A hidden service rotates nodes from the 'second_guard_set' at a random time between MIN_SECOND_GUARD_LIFETIME hours and MAX_SECOND_GUARD_LIFETIME hours. A hidden service rotates nodes from the 'third_guard_set' at a random time between MIN_THIRD_GUARD_LIFETIME and MAX_THIRD_GUARD_LIFETIME hours. These extra guard nodes should be picked with the same path selection procedure that is used for regular middle nodes (though see Section 5.1 for performance reasons to restrict this slightly). Each node's rotation time is tracked independently, to avoid disclosing the rotation times of the primary and second-level guards. XXX how should proposal 241 ("Resisting guard-turnover attacks") be applied here? 2.1. Security parameters We set NUM_SECOND_GUARDS to 4 nodes and NUM_THIRD_GUARDS to 16 nodes (ie four sets of four). XXX: 3 and 12 might be another option here, in which case our rotation period for the second guard position can be reduced to 15 days. We set MIN_SECOND_GUARD_LIFETIME to 1 day, and MAX_SECOND_GUARD_LIFETIME to 33 days, for an average rotation rate of ~11 days, using the min(X,X) distribution specified in Section 3.2.2. We set MIN_THIRD_GUARD_LIFETIME to 1 hour, and MAX_THIRD_GUARD_LIFETIME to 18 hours, for an average rotation rate of ~12 hours, using the max(X,X) distribution specified in Section 3.2.2. XXX make all the above consensus parameters? Yes. Very yes, especially if we decide to change the primary guard lifespan. See Section 3 for more analysis on these constants. 3. Rationale and Security Parameter Selection 3.1. Threat model, Assumptions, and Goals Consider an adversary with the following powers: - Can launch a Sybil guard discovery attack against any node of a rendezvous circuit. The slower the rotation period of the node, the longer the attack takes. Similarly, the higher the percentage of the network is compromised, the faster the attack runs. - Can compromise any node on the network, but this compromise takes time and potentially even coercive action, and also carries risk of discovery. We also make the following assumptions about the types of attacks: 1. A Sybil attack is noisy. It will require either large amounts of traffic, multiple test circuits, or both. 2. A Sybil attack against the second or first layer Guards will be more noisy than a Sybil attack against the third layer guard, since the second and first layer Sybil attack requires a timing side channel in order to determine success, where as the Sybil success is almost immediately obvious to third layer guard, since it will now be returned as a rend point for circuits for the hidden service in question. 3. As soon as the adversary is confident they have won the Sybil attack, an even more aggressive circuit building attack will allow them to determine the next node very fast (an hour or less). 4. The adversary is strongly disincentivized from compromising nodes that may prove useless, as node compromise is even more risky for the adversary than a Sybil attack in terms of being noticed. Given this threat model, our security parameters were selected so that the first two layers of guards should be hard to attack using a Sybil guard discovery attack and hence require a node compromise attack. Ideally, we want the node compromise attacks to carry a non-negligible probability of being useless to the adversary by the time they complete. On the other hand, the outermost layer of guards should rotate fast enough to _require_ a Sybil attack. 3.2. Parameter Tuning 3.2.1. Sybil rotation counts for a given number of Guards The probability of Sybil success for Guard discovery can be modeled as the probability of choosing 1 or more malicious middle nodes for a sensitive circuit over some period of time. P(At least 1 bad middle) = 1 - P(All Good Middles) = 1 - P(One Good middle)^(num_middles) = 1 - (1 - c/n)^(num_middles) c/n is the adversary compromise percentage In the case of Vanguards, num_middles is the number of Guards you rotate through in a given time period. This is a function of the number of vanguards in that position (v), as well as the number of rotations (r). P(At least one bad middle) = 1 - (1 - c/n)^(v*r) Here's detailed tables in terms of the number of rotations required for a given Sybil success rate for certain number of guards. 1.0% Network Compromise: Sybil Success One Two Three Four Five Six Eight Nine Ten Twelve Sixteen 10% 11 6 4 3 3 2 2 2 2 1 1 15% 17 9 6 5 4 3 3 2 2 2 2 25% 29 15 10 8 6 5 4 4 3 3 2 50% 69 35 23 18 14 12 9 8 7 6 5 60% 92 46 31 23 19 16 12 11 10 8 6 75% 138 69 46 35 28 23 18 16 14 12 9 85% 189 95 63 48 38 32 24 21 19 16 12 90% 230 115 77 58 46 39 29 26 23 20 15 95% 299 150 100 75 60 50 38 34 30 25 19 99% 459 230 153 115 92 77 58 51 46 39 29 5.0% Network Compromise: Sybil Success One Two Three Four Five Six Eight Nine Ten Twelve Sixteen 10% 3 2 1 1 1 1 1 1 1 1 1 15% 4 2 2 1 1 1 1 1 1 1 1 25% 6 3 2 2 2 1 1 1 1 1 1 50% 14 7 5 4 3 3 2 2 2 2 1 60% 18 9 6 5 4 3 3 2 2 2 2 75% 28 14 10 7 6 5 4 4 3 3 2 85% 37 19 13 10 8 7 5 5 4 4 3 90% 45 23 15 12 9 8 6 5 5 4 3 95% 59 30 20 15 12 10 8 7 6 5 4 99% 90 45 30 23 18 15 12 10 9 8 6 10.0% Network Compromise: Sybil Success One Two Three Four Five Six Eight Nine Ten Twelve Sixteen 10% 2 1 1 1 1 1 1 1 1 1 1 15% 2 1 1 1 1 1 1 1 1 1 1 25% 3 2 1 1 1 1 1 1 1 1 1 50% 7 4 3 2 2 2 1 1 1 1 1 60% 9 5 3 3 2 2 2 1 1 1 1 75% 14 7 5 4 3 3 2 2 2 2 1 85% 19 10 7 5 4 4 3 3 2 2 2 90% 22 11 8 6 5 4 3 3 3 2 2 95% 29 15 10 8 6 5 4 4 3 3 2 99% 44 22 15 11 9 8 6 5 5 4 3 The rotation counts in these tables were generated with: def count_rotations(c, v, success): r = 0 while 1-math.pow((1-c), v*r) < success: r += 1 return r 3.2.2. Rotation Period As specified in Section 3.1, the primary driving force for the third layer selection was to ensure that these nodes rotate fast enough that it is not worth trying to compromise them, because it is unlikely for compromise to succeed and yield useful information before the nodes stop being used. For this reason we chose 1 to 18 hours, with a weighted distribution (Section 3.2.3) causing the expected average to be 12 hours. From the table in Section 3.2.1, it can be seen that this means that the Sybil attack will complete with near-certainty (99%) in 29*12 hours (14.5 days) for the 1% adversary, 3 days for the 5% adversary, and 1.5 days for the 10% adversary. Since rotation of each node happens independently, the distribution of when the adversary expects to win this Sybil attack in order to discover the next node up is uniform. This means that on average, the adversary should expect that half of the rotation period of the next node is already over by the time that they win the Sybil. With this fact, we choose our range and distribution for the second layer rotation to be short enough to cause the adversary to risk compromising nodes that are useless, yet long enough to require a Sybil attack to be noticeable in terms of client activity. For this reason, we choose a minimum second-layer guard lifetime of 1 day, since this gives the adversary a minimum expected value of 12 hours for during which they can compromise a guard before it might be rotated. If the total expected rotation rate is 11 days, then the adversary can expect overall to have 5.5 days remaining after completing their Sybil attack before a second-layer guard rotates away. 3.2.3. Rotation distribution In order to skew the distribution of the third layer guard towards higher values, we use max(X,X) for the distribution, where X is a random variable that takes on values from the uniform distribution. In order to skew the distribution of the second layer guard towards low values (to increase the risk of compromising useless nodes) we skew the distribution towards lower values, using min(X,X). Here's a table of expectation (arithmetic means) for relevant ranges of X (sampled from 0..N). The current choice for second-layer guards is noted with **, and the current choice for third-layer guards is noted with ***. Range Min(X,X) Max(X,X) 10 2.85 6.15 11 3.18 6.82 12 3.51 7.49 13 3.85 8.15 14 4.18 8.82 15 4.51 9.49 16 4.84 10.16 17 5.18 10.82*** 18 5.51 11.49 19 5.84 12.16 20 6.18 12.82 21 6.51 13.49 22 6.84 14.16 23 7.17 14.83 24 7.51 15.49 25 7.84 16.16 26 8.17 16.83 27 8.51 17.49 28 8.84 18.16 29 9.17 18.83 30 9.51 19.49 31 9.84 20.16 32 10.17** 20.83 33 10.51 21.49 34 10.84 22.16 35 11.17 22.83 36 11.50 23.50 37 11.84 24.16 38 12.17 24.83 39 12.50 25.50 4. Security concerns and mitigations 4.1. Mitigating fingerprinting of new HS circuits By pinning the middle nodes of rendezvous circuits, we make it easier for all hops of the circuit to detect that they are part of a special hidden service circuit with varying degrees of certainty. The Guard node is able to recognize a Vanguard client with a high degree of certainty because it will observe a client IP creating the overwhelming majority of its circuits to just a few middle nodes in any given 10-18 day time period. The middle nodes will be able to tell with a variable certainty that depends on both its traffic volume and upon the popularity of the service, because they will see a large number of circuits that tend to pick the same Guard and Exit. The final nodes will be able to tell with a similar level certainty that depends on their capacity and the service popularity, because they will see a lot of rend handshakes that all tend to have the same second hop. The most serious of these is the Guard fingerprinting issue. When proposal xxx-padding-negotiation is implemented, services that enable this feature should use those padding primitives to create fake circuits to random middle nodes that are not their guards, in an attempt to look more like a client. Additionally, if Tor Browser implements "virtual circuits" based on SOCKS username+password isolation in order to enforce the re-use of paths when SOCKS username+passwords are re-used, then the number of middle nodes in use during a typical user's browsing session will be proportional to the number of sites they are viewing at any one time. This is likely to be much lower than one new middle node every ten minutes, and for some users, may be close to the number of Vanguards we're considering. This same reasoning is also an argument for increasing the number of second-level guards beyond just two, as it will spread the hidden service's traffic over a wider set of middle nodes, making it both easier to cover, and behave closer to a client using SOCKS virtual circuit isolation. 4.2. Hidden service linkability Multiple hidden services on the same Tor instance should use separate second and third level guard sets, otherwise an adversary is trivially able to determine that the two hidden services are co-located by inspecting their current chosen rend point nodes. Unfortunately, if the adversary is still able to determine that two or more hidden services are run on the same Tor instance through some other means, then they are able to take advantage of this fact to execute a Sybil attack more effectively, since there will now be an extra set of guard nodes for each hidden service in use. For this reason, if Vanguards are enabled, and more than one hidden service is configured, the user should be advised to ensure that they do not accidentally leak that the two hidden services are from the same Tor instance. 4.3. Denial of service Since it will be fairly trivial for the adversary to enumerate the current set of rend nodes for a hidden service, denial of service becomes a serious risk for Vanguard users. For this reason, it is important to support a large number of third-level guards, to increase the amount of resources required to bring a hidden service offline by DoSing just a few Tor nodes. 5. Performance considerations The switch to a restricted set of nodes will very likely cause significant performance issues, especially for high-traffic hidden services. If any of the nodes they select happen to be temporarily overloaded, performance will suffer dramatically until the next rotation period. 5.1. Load Balancing Since the second and third level "guards" are chosen from the set of all nodes eligible for use in the "middle" hop (as per hidden services today), this proposal should not significantly affect the long-term load on various classes of the Tor network, and should not require any changes to either the node weight equations, or the bandwidth authorities. Unfortunately, transient load is another matter, as mentioned previously. It is very likely that this scheme will increase instances of transient overload at nodes selected by high-traffic hidden services. One option to reduce the impact of this transient overload is to restrict the set of middle nodes that we chose from to some percentage of the fastest middle-capable relays in the network. This may have some impact on load balancing, but since the total volume of hidden service traffic is low, it may be unlikely to matter. 5.2. Circuit build timeout The adaptive circuit build timeout mechanism in Tor is what corrects for instances of transient node overload right now. The timeout will naturally tend to select the current fastest and least-loaded paths even through this set of restricted routes, but it may fail to behave correctly if there are a very small set of nodes in each guard set, as it is based upon assumptions about the current path selection algorithm, and it may need to be tuned specifically for Vanguards, especially if the set of possible routes is small. 5.3. OnionBalance At first glance, it seems that this scheme makes multi-homed hidden services such as OnionBalance[1] even more important for high-traffic hidden services. Unfortunately, if it is equally damaging to the user for any of their multi-homed hidden service locations to be discovered, then OnionBalance is strictly equivalent to simply increasing the number of second-level guard nodes in use, because an active adversary can perform simultaneous Sybil attacks against all of the rend points offered by the multi-homed OnionBalance introduction points. 5.4. Default vs optional behavior We suggest this torrc option to be optional because it changes path selection in a way that may seriously impact hidden service performance, especially for high traffic services that happen to pick slow guard nodes. However, by having this setting be disabled by default, we make hidden services who use it stand out a lot. For this reason, we should in fact enable this feature globally, but only after we verify its viability for high-traffic hidden services, and ensure that it is free of second-order load balancing effects. Even after that point, until Single Onion Services are implemented, there will likely still be classes of very high traffic hidden services for whom some degree of location anonymity is desired, but for which performance is much more important than the benefit of Vanguards, so there should always remain a way to turn this option off. 6. Future directions Here are some more ideas for improvements that should be done sooner or later: - Maybe we should make the size and rotation period of secondary/third guard sets to be configurable by the user. - To make it harder for an adversary, a hidden service MAY extend the path length of its circuits by an additional static hop. This forces the adversary to use another coercion attack to walk the chain up to the hidden service. 7. Acknowledgments Thanks to Aaron Johnson, John Brooks, Mike Perry and everyone else who helped with this idea. 1. https://onionbalance.readthedocs.org/en/latest/design.html#overview -- Mike Perry

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onionoo.tpo stuck at 2016-05-13 12:00
by nusenu 29 Jan '17

29 Jan '17

Hi Karsten, I was surprised that ornetradar did not send a single email for yesterday's new relays. After looking into it, it turned out it is an onionoo problem. "relays_published":"2016-05-13 12:00:00" https://onionoo.torproject.org/details?limit=4 regards, nusenu

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Joining Tor Project's software infrastructure
by Jesse V 14 Nov '16

14 Nov '16

Hey everyone, Although it hasn't been obvious, I actually have been making some serious progress on my Onion Name System (OnioNS) project. The paper was accepted into PoPETS, the design is finally stable, and the software is looking really promising, although not yet ready for use. I've focused on improving the maturity of the software and set up the following: * PGP-signed commits using my torproject identity * Continuous integration via Travis CI * Use clang-analyzer and cppcheck static analysis scanners * Automated enforcement of code styling via clang-format * Inclusion of a manpage and command-line help menu * Packaging for Debian (Wheezy+) on my own machine * Automated building for Ubuntu (14.04+) on Launchpad * Protection against memory leaks and buffer overflows * Software is split to minimize installation footprint * Use of CMake, which should help the port to Windows * No RPATH hacks * Support for release and debug builds * Support for Clang and GCC; all warnings enabled for debug * No reliance on OpenSSL (CVE-2016-6309, are you serious?!) * Use of well-maintained libraries for networking and parsing * Minimal dependencies: Botan, JsonCpp, libcurl, libmicrohttpd * Non-native dependencies included as git submodules At this point, I am interested in taking the next step and try to integrate with the Tor Project infrastructure. I am looking for information on the following: 1) How do I upload packages to deb.torproject.org? 2) How do I join Gitian to generate reproducible builds? 3) How do I set up an Onion Name System component in Trac so that I can migrate bug tracking from Github to Trac? 4) How do I set up a repository on gitweb.torproject.org? I'm more comfortable using Github, but there's no need to centralize git. I have a LDAP account, which should help with some of these. I wasn't able to find much useful documentation on these topics, so I would appreciate some help. Also, if anyone has any experience with RPM packaging, I would like to figure that out. I haven't had too much luck with Alien. As I approach a proper release, my overall goal is to improve the maturity, trust, usability of the OnioNS software. Please let me know how I can accomplish the above tasks. Recent commits: https://github.com/Jesse-V/OnioNS-common/tree/json-rpc https://github.com/Jesse-V/OnioNS-server/tree/json-rpc https://github.com/Jesse-V/OnioNS-client/tree/json-rpc I've also updated https://trac.torproject.org/projects/tor/wiki/doc/OnionServiceNamingSystems -- Jesse

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[Proposal] A simple way to make Tor-Browser-Bundle more portable and secure
by Daniel Simon 31 Oct '16

31 Oct '16

Hello. How it's currently done - The Tor Browser Bundle is dynamically linked against glibc. Security problem - The Tor Browser Bundle has the risk of information about the host system's library ecosystem leaking out onto the network. Portability problem - The Tor Browser Bundle can't be run on systems that don't use glibc, making it unusable due to different syscalls. Solution proposed - Static link the Tor Browser Bundle with musl libc.[1] It is a simple and fast libc implementation that was especially crafted for static linking. This would solve both security and portability issues. What is Tor developers' opinion about this? I personally don't see any drawbacks and would be interested in discussing this further. Sincerely, Daniel [1] https://www.musl-libc.org/

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Potential regression when binding sockets to interface without default route
by René Mayrhofer 25 Oct '16

25 Oct '16

Dear Tor developers, [Please CC me in replies, I am not currently subscribed to tor-dev.] Context: At the Institute of Networks and Security at Johannes Kepler University Linz, we have been hosting Austria's fastest exit node for the last ca. 9 months. It used to be listed as https://atlas.torproject.org/#details/01A9258A46E97FF8B2CAC7910577862C14F2C… until very recently, and we tried to find out what went wrong when we saw traffic drop sharply a bit over a week ago. Unfortunately, two out of three people responsible for running this node were on holidays, so we could only start investigating today. Setup: Please note that our setup is a bit particular for reasons that we will explain in more detail in a later message (including a proposed patch to the current source which has been pending also because of the holiday situation...). Briefly summarizing, we use a different network interface for "incoming" (Tor encrypted traffic) than for "outgoing" (mostly clearnet traffic from the exit node, but currently still includes outgoing Tor relay traffic to other nodes). The outgoing interface has the default route associated, while the incoming interface will only originate traffic in response to those incoming connections. Consequently, we let our Tor node only bind to the IP address assigned to the incoming interface 193.171.202.146, while it will initiate new outgoing connections with IP 193.171.202.150. Problem: This worked nicely with Tor 0.2.5.12-1 on Debian Jessie. We upgraded about two weeks ago to 0.2.8.7-1 from the Tor apt repositories (mostly in response to https://blog.torproject.org/blog/tor-0287-released-important-fixes as a wakeup call that we were using old versions from Debian main). At first, it seemed to work well enough, but then the holidays came and we didn't actively watch it for the next week.... Now with 0.2.8.7-1, the traffic sent to our node started declining until it vanished completely. After a bit of debugging and rolling back to 0.2.5.12-1 (which is now active on our node as of a few hours ago, slowly approaching the 200MBit/s again), it seems that we discovered a regression concerning the handling of sockets. I can best summarize it with the relevant torrc config options and startup log lines from both versions: root@tor2 ~ # grep 193.171.202 /etc/tor/torrc ORPort 193.171.202.146:9001 ORPort 193.171.202.146:443 OutboundBindAddress 193.171.202.150 DirPort 193.171.202.146:9030 Sep 19 11:37:41.000 [notice] Tor 0.2.8.7 (git-cc2f02ef17899f86) opening log file. Sep 19 11:37:41.194 [notice] Tor v0.2.8.7 (git-cc2f02ef17899f86) running on Linux with Libevent 2.0.21-stable, OpenSSL 1.0.1t and Zlib 1.2.8. Sep 19 11:37:41.194 [notice] Tor can't help you if you use it wrong! Learn how to be safe at https://www.torproject.org/download/download#warning Sep 19 11:37:41.194 [notice] Read configuration file "/usr/share/tor/tor-service-defaults-torrc". Sep 19 11:37:41.194 [notice] Read configuration file "/etc/tor/torrc". Sep 19 11:37:41.197 [warn] You specified a public address '0.0.0.0:9050' for SocksPort. Other people on the Internet might find your computer and use it as an open proxy. Please don't allow this unless you have a good reason. Sep 19 11:37:41.198 [notice] Based on detected system memory, MaxMemInQueues is set to 2961 MB. You can override this by setting MaxMemInQueues by hand. Sep 19 11:37:41.198 [warn] Tor is running as an exit relay. If you did not want this behavior, please set the ExitRelay option to 0. If you do want to run an exit Relay, please set the ExitRelay option to 1 to disable this warning, and for forward compatibility. Sep 19 11:37:41.198 [warn] You specified a public address '0.0.0.0:9050' for SocksPort. Other people on the Internet might find your computer and use it as an open proxy. Please don't allow this unless you have a good reason. Sep 19 11:37:41.199 [notice] Opening Socks listener on 0.0.0.0:9050 Sep 19 11:37:41.199 [notice] Opening Control listener on 127.0.0.1:9051 Sep 19 11:37:41.199 [notice] Opening OR listener on 193.171.202.146:9001 Sep 19 11:37:41.199 [notice] Opening OR listener on 193.171.202.146:443 Sep 19 11:37:41.199 [notice] Opening Directory listener on 193.171.202.146:9030 Sep 19 11:37:41.000 [notice] Parsing GEOIP IPv4 file /usr/share/tor/geoip. Sep 19 11:37:41.000 [notice] Parsing GEOIP IPv6 file /usr/share/tor/geoip6. Sep 19 11:37:41.000 [notice] Configured to measure statistics. Look for the *-stats files that will first be written to the data directory in 24 hours from now. Sep 19 11:37:41.000 [warn] I have no descriptor for the router named "ins1" in my declared family; I'll use the nickname as is, but this may confuse clients. Sep 19 11:37:41.000 [warn] I have no descriptor for the router named "ins2" in my declared family; I'll use the nickname as is, but this may confuse clients. Sep 19 11:37:41.000 [notice] Your Tor server's identity key fingerprint is 'ins0 01A9258A46E97FF8B2CAC7910577862C14F2C524' Sep 19 11:37:41.000 [notice] Bootstrapped 0%: Starting Sep 19 11:37:49.000 [notice] Bootstrapped 80%: Connecting to the Tor network Sep 19 11:37:49.000 [notice] Signaled readiness to systemd Sep 19 11:37:50.000 [notice] Opening Control listener on /var/run/tor/control Sep 19 11:37:51.000 [notice] Bootstrapped 85%: Finishing handshake with first hop Sep 19 11:37:51.000 [notice] Bootstrapped 90%: Establishing a Tor circuit Sep 19 11:37:51.000 [notice] Tor has successfully opened a circuit. Looks like client functionality is working. Sep 19 11:37:51.000 [notice] Bootstrapped 100%: Done Sep 19 11:37:51.000 [notice] Now checking whether ORPort 193.171.202.150:9001 and DirPort 193.171.202.150:9030 are reachable... (this may take up to 20 minutes -- look for log messages indicating success) Sep 19 11:38:30.000 [notice] Self-testing indicates your ORPort is reachable from the outside. Excellent. Sep 19 11:38:34.000 [warn] You specified a server "ins1" by name, but the directory authorities do not have any key registered for this nickname -- so it could be used by any server, not just the one you meant. To make sure you get the same server in the future, refer to it by key, as "$CD9FD887A4572D46938640BA65F258851F1E418B". Sep 19 11:38:34.000 [warn] You specified a server "ins2" by name, but the directory authorities do not have any key registered for this nickname -- so it could be used by any server, not just the one you meant. To make sure you get the same server in the future, refer to it by key, as "$7C3AF46F77445A0B1E903A5AF5B730A05F127BFC". Sep 19 11:40:18.000 [notice] Performing bandwidth self-test...done. Sep 19 11:57:50.000 [warn] Your server (193.171.202.150:9030) has not managed to confirm that its DirPort is reachable. Relays do not publish descriptors until their ORPort and DirPort are reachable. Please check your firewalls, ports, address, /etc/hosts file, etc. Sep 19 12:00:27.000 [notice] Interrupt: we have stopped accepting new connections, and will shut down in 30 seconds. Interrupt again to exit now. Sep 19 12:00:57.000 [notice] Clean shutdown finished. Exiting. Sep 19 12:01:48.000 [notice] Tor 0.2.5.12 (git-3731dd5c3071dcba) opening log file. Sep 19 12:01:48.000 [notice] Configured to measure directory request statistics, but no GeoIP database found. Please specify a GeoIP database using the GeoIPFile option. Sep 19 12:01:48.000 [notice] Caching new entry debian-tor for debian-tor Sep 19 12:01:48.000 [notice] Caching new entry debian-tor for debian-tor Sep 19 12:01:48.000 [warn] I have no descriptor for the router named "ins1" in my declared family; I'll use the nickname as is, but this may confuse clients. Sep 19 12:01:48.000 [warn] I have no descriptor for the router named "ins2" in my declared family; I'll use the nickname as is, but this may confuse clients. Sep 19 12:01:48.000 [notice] Your Tor server's identity key fingerprint is 'ins0 01A9258A46E97FF8B2CAC7910577862C14F2C524' Sep 19 12:01:48.000 [notice] Bootstrapped 0%: Starting Sep 19 12:01:48.000 [notice] Bootstrapped 5%: Connecting to directory server Sep 19 12:01:51.000 [notice] We now have enough directory information to build circuits. Sep 19 12:01:51.000 [notice] Bootstrapped 80%: Connecting to the Tor network Sep 19 12:01:51.000 [notice] Bootstrapped 85%: Finishing handshake with first hop Sep 19 12:01:52.000 [notice] Bootstrapped 90%: Establishing a Tor circuit Sep 19 12:01:52.000 [notice] Tor has successfully opened a circuit. Looks like client functionality is working. Sep 19 12:01:52.000 [notice] Bootstrapped 100%: Done Sep 19 12:01:52.000 [notice] Now checking whether ORPort 193.171.202.146:9001 and DirPort 193.171.202.146:9030 are reachable... (this may take up to 20 minutes -- look for log messages indicating success) Sep 19 12:01:53.000 [notice] Self-testing indicates your DirPort is reachable from the outside. Excellent. Sep 19 12:01:53.000 [notice] Self-testing indicates your ORPort is reachable from the outside. Excellent. Publishing server descriptor. Sep 19 12:01:55.000 [notice] Performing bandwidth self-test...done. Please note the difference (0.2.8.7): Sep 19 11:37:51.000 [notice] Now checking whether ORPort 193.171.202.150:9001 and DirPort 193.171.202.150:9030 are reachable... (this may take up to 20 minutes -- look for log messages indicating success) vs. (0.2.5.12): Sep 19 12:01:52.000 [notice] Now checking whether ORPort 193.171.202.146:9001 and DirPort 193.171.202.146:9030 are reachable... (this may take up to 20 minutes -- look for log messages indicating success) I.e. 0.2.8.7 does not seem to honor the address the socket is bound to when starting the reachability checks from the outside (it seems to use the address that either the default route is associated with or the OutboundBindAddress) - although the socket binding itself is done correctly (i.e. the netstat output is exactly the same for both versions, with tor binding to the specific IP address only for the Dir and both OR ports). Consequently, the node is declared as non-reachable and drops off the globe/atlas... Has this change been intentional? I have to admit we have not yet checked the source code for further debugging, as we wanted to get the node back up as quickly as possible (after our unfortunately timed holidays, sorry for that). with best regards, Rene

5 20

Tor Browser downloads and updates graphs
by Georg Koppen 09 Oct '16

09 Oct '16

Hi all! So, Karsten, Nicolas and I were sitting together for a while and were looking at past data for figuring out how many users downloaded and updated their Tor Browser over time. We actually got more questions than we were able to answer but I guess that's fine for a start. Here are the graphs showing initial downloads, update pings and update requests over time: https://people.torproject.org/~karsten/volatile/torbrowser-annotated-2016-0… We annotated the grapgs a bit highlighting things we wanted people to point to. The initial downloads are the number of package downloads from the website for all supported platforms (Windows, OS X and Linux). Apart from spike (5) all events seem to be non-Tor Browser related. * On the downloads graph we seem to have a spike (5) in new downloads with the release of Tor Browser 6.0. Maybe because it was much more widely publicized in the media than previous/later releases? * On the same graph, a big spike (6) can be seen at the same day the new board got announced. * There are other spikes on the initial downloads graph (1, 3, 4) where we have no idea what happened while (2) is probably just an outlier. The update pings are made by Tor Browser instances roughly twice a day and they indicate the number of active Tor Browser users. More importantly, one can see the decrease or increase of Tor Browser usage over time. * As (2) in the downloads graph (7) seems to be an outlier as well. * We don't know what (8) or (9) is but it seems to us we are losing users over time and are only getting them back slowly if at all. A weekday/weekend pattern is visible there as well. The graph with the update requests is basically showing how fast users are updating to newly released Tor Browser versions. * (10) shows a large spike correlating to the 6.0 release. It is not clear to us where all those update requests were coming from given the update request pattern before/after 6.0. One plausible explanation could be that our infrastructure was heavily overloaded causing clients to retry fetching the update. We'd love to hear feedback, especially those that could shed light on the events we did not have an explanation for. Georg

11 21

Re: [tor-dev] Onioncat and Prop224
by str4d 09 Oct '16

09 Oct '16

On 27/04/16 22:31, grarpamp wrote: > On 4/25/16, Tim Wilson-Brown - teor <teor2345(a)gmail.com> wrote: >> >>> On 22 Apr 2016, at 17:03, grarpamp <grarpamp(a)gmail.com> wrote: >>> >>> FYI: The onioncat folks are interested in collaborating >>> with tor folks regarding prop224. >>> >>> https://gitweb.torproject.org/torspec.git/tree/proposals/224-rend-spec-ng.t… >> >> I'm interested in what kind of collaboration onioncat would like to do on >> prop224, next-generation hidden services. >> It would be great to work this out in the next few weeks, as we're coding >> parts of the proposal right now. > > Yep :) And I know Bernhard was hoping to get in touch with Roger > on this before long. > > Basically, prop224 HS being wider than 80 bits will break onioncat's > current HS onion <---> IPv6 addressing mechanism. > > They're looking at various backward compatibility options, as well > as possibly making side use of the HSDir DHT, or even integrating > more directly with the tor client. > Just FYI, I recently migrated all of I2P's spec proposals to the website, and came across a seven-year-old proposal that Bernhard wrote about improving I2P support in GarliCat: https://geti2p.net/spec/proposals/105-garlicat-name-translation I don't know how well it has aged, but given that Tor is now facing the same issues that I2P has, perhaps it can be of some use if resurrected from the dead :) > >> But the tor-onions mailing list is to discuss the technical details running >> onion services. > > Readers of tor-onions / newbies may have been unfamiliar with > onioncat. It's a way to get non-TCP between TorHS onions, thus in > the thread "Hidden datagram service". > > I think there are a nontrivial number of users interested in, and > using, non-strictly-TCP transport over an IPv6 tunnel interface. > For example, look at users of CJDNS... > > For which we should try to continue a way, in v2, to do that over > anonymous overlay network Tor / I2P. > There is already some work on doing this in I2P: https://github.com/majestrate/i2p-tools/tree/master/i2tun https://github.com/majestrate/i2p-tools/tree/master/pyi2tun I2P also natively supports non-TCP protocols if that helps (only datagrams implemented thus far). str4d

9 20

uProxy adds Tor support
by David Fifield 30 Sep '16

30 Sep '16

https://blog.uproxy.org/2016/09/uproxy-adds-tor-support.html This blog post says that uProxy gained support for proxying others' traffic through Tor. uProxy client → censor → uProxy server → Tor → destination In the classic uProxy deployment scenario, the client and server are people who know each other. (I say "classic" because there are other deployment modalities now.) They each run a browser extension. The client encapsulates its web traffic and sends it to the server over WebRTC. The server then issues the web requests and sends the responses back over the WebRTC channel. A potential problem is that the uProxy server's own web browsing gets mixed up with that of the client. The client could, for example, get the server in trouble by accessing sketchy web sites. That's what the Tor integration is meant to solve.

1 0

Thesis using QUIC in Tor
by Ali Clark 30 Sep '16

30 Sep '16

Hi all, For my master's thesis this summer I looked into the performance impact from using QUIC instead of TCP/TLS as the relay transport. Results from the experiments look quite promising. For more details and the thesis, please see my blog post: https://www.benthamsgaze.org/2016/09/29/quux-a-quic-un-multiplexing-of-the-… I'm happy to respond to questions either here or in comments on the blog post. Ali

2 2

Constraining Ephemeral Service Creation in Tor
by bancfc＠openmailbox.org 29 Sep '16

29 Sep '16

Hello, We are working on supporting ephemeral onion services in Whonix and one of the concerns brought up is how an attacker can potentially exhaust resources like RAM. CPU, entropy... on the Gateway (or system in the case of TAILS) by requesting an arbitrary number of services and ports to be created. In our opinion, options in core Tor for setting a maximum number of services and ports per service seems the right way to go about it. Also rate limiting the requests (like you do with NEWNYM) would be a sensible thing to do. What are your opinions about this?

2 2

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tor-dev September 2016