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Hidden service patch workshop on #tor-dev IRC channel
by George Kadianakis 09 Nov '15

09 Nov '15

Dear tor-dev, Everyone who is working on any kind of improvement to hidden services or related applications and would like to give or receive assistance (code reviews, advice, etc.) is welcome on: Thursday November 12, 16:00 UTC @ #tor-dev OFTC channel This might become a regular biweekly thing, if it proves to be successful. Cheers!

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Re: [tor-dev] [tor-commits] [tor-messenger-build/master] Bug 17492: Include default bridges configuration
by Roger Dingledine 09 Nov '15

09 Nov '15

On Sat, Nov 07, 2015 at 12:13:45AM +0000, boklm(a)torproject.org wrote: > commit 7a1c6fd121dd001eb999ef03ebbbed264da37026 > Author: Nicolas Vigier <boklm(a)torproject.org> > Date: Sat Nov 7 00:45:48 2015 +0100 > > Bug 17492: Include default bridges configuration > > However, we exclude meek from the bridges configuration, as it currently > doesn't work in Tor Messenger because it requires firefox. This could be a great opportunity for Yawning's recent meek variant that doesn't use an actual browser. (It won't work as well as the real meek, but maybe no actual adversaries care about the difference quite yet?) --Roger

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Ideas for TorBrowser
by Michał Dziczkowski 06 Nov '15

06 Nov '15

Hello. I would like to propose following for the TorBrowser: * request folder structure change because the actual one is a big mess and it's hard to find anything without browsing each folder * add the patches with fix the bugs of not working functions (like by example: options, addons, etc.) of current version of browser (till the next version of TorBrowser get ready to download) Mcgiwer

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Mail Address Translation Protocol Tor>Internet, Internet<Tor
by Liste 06 Nov '15

06 Nov '15

Enter/Exit OnionMail SMTP servers connect the Internet and Tor. The addressed must be translated from hidden service address to Internet address ad viceversa. There are some way to do this: MAT = Mail Address Translation: localpart.hiddenservice.onion(a)internetServer.tld = localpart(a)hiddenservice.onion VMAT = Virtual Mail Address Translation: localpart1(a)internetServer.tld = localpart2(a)hiddenservice.onion (With public Database) SMAT = Scrambled Mail Address Translation: base32encryptedWithHC256Address-HiddenServiceIdAndSalt.so(a)internetServer.tld = localpart(a)hiddenservice.onion (With private hidden service salt and id; without database). VCMAT = Virtual circuit VMAT. localpart2.vc(a)internetServer.tld = (firstHop.vc(a)server.onion) = (secondHop.vc(a)server.onion) = ... (nHop.vc(a)server.onion) = localpart(a)hiddenservice.onion (False connection). (False connection). Available from OnionMail2. And others.... Valid characters of localpart: [a-zA-Z0-9\-\.\_] The last part after the character dot "." declare the type of address. *.onion = M.A.T. Address. *.list = Mailing list. *.news = Newsgroup. *.op = SysOp reserved. *.app = Applications / bot. *.sys = OnionMail system. *.so = Scrambled VMAT. *.vc or *.iam = Virtual circuit VMAT. *.o = VMAT 3 Reserved. *.tor (or other word with 3 ot less characters) = Old only Tor address protocol (Removed in OnionMail 1.8.1 Alpha). *.a = Anonymous remailer address. *.x = Reserved. sysop = SysOp System administrator. server = Server bot. All others *.* are free for user as normal address local part. Example: user.wxyz(a)hiddenservice.onion is a normal user's OnionMail address. (The MAT address is: user.wxyz.hiddenservice.onion(a)internetSevewr.tld ) Some address functions may be encapsulated. *.list.*.onion(a)internetServer.tld = A mailing list MAT address. OR *.list(a)internetServer.tld = VMAT address of a mailing list. VMAT Mail type must be the same of tor address type. The special characters: +~ and others, except -_ Reserved for future use. The special address: iam.onion The meaning of this invalid hidden service address is "the otherside address". Can be used to set the local addresses on the same server only for special users like: sysop(a)iam.onion, server(a)iam.onion This address is used by TORM IAM request by the OnionMail server's IAM/InterNos protocol. for example if you send a request "TORM IAM iam.onion V2" you will receive the server's manifest without reversed request. All IP addresses are set to [0.0.0.0]

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Proposal 258: Denial-of-service resistance for directory authorities
by Nick Mathewson 06 Nov '15

06 Nov '15

[Here's a new proposal from Andrea. See ticket 4581 for implementation details.] Filename: 258-dirauth-dos.txt Title: Denial-of-service resistance for directory authorities Author: Andrea Shepard Created: 2015-10-27 Status: Open 1. Problem statement The directory authorities are few in number and vital for the functioning of the Tor network; threats of denial of service attacks against them have occurred in the past. They should be more resistant to unreasonably large connection volumes. 2. Design overview There are two possible ways a new connection to a directory authority can be established, directly by a TCP connection to the DirPort, or tunneled inside a Tor circuit and initiated with a begindir cell. The client can originate the former as direct connections or from a Tor exit, and the latter either as fully anonymized circuits or one-hop links to the dirauth's ORPort. The dirauth will try to heuristically classify incoming requests as one of these four indirection types, and then in the two non-anonymized cases further sort them into hash buckets on the basis of source IP. It will use an exponentially-weighted moving average to measure the rate of connection attempts in each bucket, and also separately limit the number of begindir cells permitted on each circuit. It will periodically scan the hash tables and forget counters which have fallen below a threshold to prevent memory exhaustion. 3. Classification of incoming connections Clients can originate connections as one of four indirection types: - DIRIND_ONEHOP: begindir cell on a single-hop Tor circuit - DIRIND_ANONYMOUS: begindir cell on a fully anonymized Tor circuit - DIRIND_DIRECT_CONN: direct TCP connection to dirport - DIRIND_ANON_DIRPORT: TCP connection to dirport from an exit relay The directory authority can always tell a dirport connection from a begindir, but it must use its knowledge of the current consensus and exit policies to disambiguate whether the connection is anonymized. It should treat a begindir as DIRIND_ANONYMOUS when the previous hop in the circuit it appears on is in the current consensus, and as DIRIND_ONEHOP otherwise; it should treat a dirport connection as DIRIND_ANON_DIRPORT if the source address appears in the consensus and allows exits to the dirport in question, or as DIRIND_DIRECT_CONN otherwise. In the case of relays which also act as clients, these heuristics may falsely classify direct/onehop connections as anonymous, but will never falsely classify anonymous connections as direct/onehop. 4. Exponentially-weighted moving average counters and hash table The directory authority implements a set of exponentially-weighted moving averages to measure the rate of incoming connections in each bucket. The two anonymous connection types are each a single bucket, but the two non- anonymous cases get a single bucket per source IP each, stored in a hash table. The directory authority must periodically scan this hash table for counters which have decayed close to zero and free them to avoid permitting memory exhaustion. This introduces five new configuration parameters: - DirDoSFilterEWMATimeConstant: the time for an EWMA counter to decay by a factor of 1/e, in seconds. - DirDoSFilterMaxAnonConnectRate: the threshold to trigger the DoS filter on DIRIND_ANONYMOUS connections. - DirDoSFilterMaxAnonDirportConnectRate: the threshold to trigger the DoS filter on DIRIND_ANON_DIRPORT connections. - DirDoSFilterMaxBegindirRatePerIP: the threshold per source IP to trigger the DoS filter on DIRIND_ONEHOP connections. - DirDoSFilterMaxDirectConnRatePerIP: the threshold per source IP to trigger the DoS filter on DIRIND_DIRECT_CONN connections. When incrementing a counter would put it over the relevant threshold, the filter is said to be triggered. In this case, the directory authority does not update the counter, but instead suppresses the incoming request. In the DIRIND_ONEHOP and DIRIND_ANONYMOUS cases, the directory authority must kill the circuit rather than merely refusing the request, to prevent an unending stream of client retries on the same circuit. 5. Begindir cap Directory authorities limit the number of begindir cells permitted in the lifetime of a particular circuit, separately from the EWMA counters. This can only affect the DIRIND_ANONYMOUS and DIRIND_ONEHOP connetion types. A sixth configuration variable, DirDoSFilterMaxBegindirPerCircuit, controls this feature. 6. Limitations Widely distributed DoS attacks with many source IPs may still be able to avoid raising any single DIRIND_ONEHOP or DIRIND_DIRECT_CONN counter above threshold.

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Re: [tor-dev] stale entries in bwscan.20151029-1145
by starlight.2015q3＠binnacle.cx 06 Nov '15

06 Nov '15

aAt 20:56 11/5/2015 -0600, you wrote: >On 5 November 2015 at 16:37, <starlight.2015q3(a)binnacle.cx> wrote: >> By having a single thread handle >> consensus retrieval and sub-division, >> issues of "lost" relays should >> go away entirely. > >So I'm coming around to this idea, after spending >an hour trying to explain why it was bad. . . :-D happy to hear that It can be expressed and implemented various ways, but the core idea of centralizing this function is hard to escape. >So the >main problem as I see it is that it's easy to move >relays between slices that haven't happened yet - >but how do you do this when some slices are >completed and some aren't? >. . .if you used a work queue instead of a scanner. . . I'm thinking of it more as a set of circular work lists, since scanning never ends. Not then a question of "haven't happened yet" for new relays since regardless of where they're inserted they will be measured. More a question of giving priority to new relays and giving priority to relays that have exhibited a large change of bandwidth, particularly in the downward direction. If radical restructuring is on the menu (as the remainder of your comments imply) let me put out an idea I've come up with: I'm not enthusiastic about the current design where nine scanners blindly compete with each other for the local Tor client-router and link bandwidth. The goal should be to figure out what percent of the BWauth link's bandwidth should be consumed to minimize scanning time while ensuring quality measurement. Nine scanners could be replaced with one scanner that runs the entire list of relays sorted from fastest to slowest. This scanner would keep the slice approach of firing-up scans until a quota is filled. But instead of that quota being a somewhat arbitrary fixed value, the quota would be a minimum bandwidth target per the output of 'SETEVENTS BW'. A rough guess is that whatever bandwidth is available should be 35% subscribed, though the actual setting would require empirical determination. On a 100mbps link the target might then be a continuous 4.5 million bytes/sec of scanning. This might result in the 100 or so fastest relays being measured one-at-time, but of course it would happen rather quickly. As the scanner works down the list the number of concurrent scans would rise rapidly as the bandwidth of the targets decline and so perhaps several hundred of the slowest relays would be under measurement near the end of each pass. My belief is the end result would be dramatically faster than the current approach, have a low circuit-fail rate, and that the measurements would be far more reliable and consistent. >FWIW, looking at >https://bwauth.ritter.vg/bwauth/AA_scanner_loop_times.txt , it >seems like (for whatever weird reason) scanner1 took way longer than >the others. (Scanner 9 is very different, so ignore that one.) > >Scanner 1 > 5 days, 11:07:27 Yes noticed this a few days ago, examined ticket 17482 more closely and saw it was 6.5 days for scanner-one just before the 10/30 restart. The scanner-one log shows huge numbers of circuit failures. Observation partly inspired the above restructuring idea.

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Re: [tor-dev] stale entries in bwscan.20151029-1145
by starlight.2015q3＠binnacle.cx 06 Nov '15

06 Nov '15

At 11:47 11/5/2015 -0600, Tom Ritter wrote: > . . . >So them falling between the slices would be my >best guess. . . Immediately comes to mind that dealing with the changing consensus while scanning might be handled in a different but nonetheless straightforward manner. Why not create a snapshot of the consensus at the time scanning commences then-- without disturbing the scanners-- pull each new update with an asynchronous thread or process. The consensus thread would diff against the previous state snapshot and produce an updated snapshot plus deltas for each scanner and/or slice as the implementation requires. Then briefly lock the working list for each active scanner and apply the delta to it. By having a single thread handle consensus retrieval and sub-division, issues of "lost" relays should go away entirely. No need to hold locks for extended periods. The consensus allocation thread would run continuously, so individual slices and scanners can complete and restart asynchronous to each other without glitches or delays. Consensus allocation worker could also manage migrating relays from one scanner to another, again preventing lost relays.

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[proposal] New Entry Guard Selection Algorithm
by isis 06 Nov '15

06 Nov '15

Hello, For your reviewing pleasure, may I present you with a new (draft) proposal for a new entry guard selection algorithm, and associated data structures (with reference implementations!). [0] The bulk of it is based upon George Kadianakis' recent email and pseudocode. [1] [2] There are still a few XXXs which need elucidation and/or comment. Relevant tickets include: https://bugs.torproject.org/17261 https://bugs.torproject.org/17262 https://bugs.torproject.org/16120 https://bugs.torproject.org/12466 https://bugs.torproject.org/12450 https://bugs.torproject.org/12595 Assistance with the completion of #17262 (due 31 Oct) would be greatly appreciated, since my plan for tomorrow is to work with some of the cryptographers here to review my changes to the crypto in rBridge for #7520. [0]: https://gitweb.torproject.org/user/isis/torspec.git/commit/?h=bug17261-best… [1]: https://lists.torproject.org/pipermail/tor-dev/2015-August/009328.html [2]: https://gitweb.torproject.org/user/asn/tor.git/tree/src/or/guardlist.c?h=bu… Best regards, -- ♥Ⓐ isis agora lovecruft _________________________________________________________ OpenPGP: 4096R/0A6A58A14B5946ABDE18E207A3ADB67A2CDB8B35 Current Keys: https://blog.patternsinthevoid.net/isis.txt

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Re: [tor-dev] stale entries in bwscan.20151029-1145
by starlight.2015q3＠binnacle.cx 05 Nov '15

05 Nov '15

At 11:47 11/5/2015 -0600, Tom Ritter wrote: > . . . >So them falling between the slices would be my >best guess. . . Immediately comes to mind that dealing with the changing consensus while scanning might be handled in a different but nonetheless straightforward manner. Why not create a snapshot of the consensus at the time scanning commences then-- without disturbing the scanners-- pull each new update with an asynchronous thread or process. The consensus thread would diff against the previous state snapshot and produce an updated snapshot plus deltas for each scanner and/or slice as the implementation requires. Then briefly lock the working list for each active scanner and apply the delta to it. By having a single thread handle consensus retrieval and sub-division, issues of "lost" relays should go away entirely. No need to hold locks for extended periods. The consensus allocation thread would run continuously, so individual slices and scanners can complete and restart asynchronous to each other without glitches or delays. Consensus allocation worker could also manage migrating relays from one scanner to another, again preventing lost relays.

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Re: [tor-dev] stale entries in bwscan.20151029-1145
by Tom Ritter 05 Nov '15

05 Nov '15

[+tor-dev] So... weird. I dug into Onyx primarily. No, in scanner.1/scan-data I cannot find any evidence of Onyx being present. I'm not super familiar with the files torflow produces, but I believe the bws- files list what slice each relay is assigned to. I've put those files (concatted) here: https://bwauth.ritter.vg/bwauth/bws-data Those relays are indeed missing. Mike: is it possible that relays are falling in between _slices_ as well as _scanners_? I thought the 'stop listening for consensus' commit would mean that for a single scanner would use the same consensus for all the slices in the scanner... -tom [0] https://gitweb.torproject.org/torflow.git/commit/NetworkScanners/BwAuthorit… On 5 November 2015 at 10:48, <starlight.2015q4(a)binnacle.cx> wrote: > Hi Tom, > > Scanner 1 finally finished the first pass. > > Of the list of big relays not checked > below, three are still not checked: > > *Onyx 10/14 > atomicbox1 10/21 > *naiveTorer 10/15 > > Most interesting, ZERO evidence of > any attempt to use the two starred > entries appears in the scanner log. > 'atomicbox1' was used to test > other relays but was not tested > itself. > > Can you look in the database files > to see if any obvious reason for > this exists? These relays are > very fast, Stable-flagged relays > that rank near the top of the > Blutmagie list. > > > > > >>Date: Thu, 29 Oct 2015 19:57:52 -0500 >>To: Tom Ritter <tom(a)ritter.vg> >>From: starlight.2015q4(a)binnacle.cx >>Subject: Re: stale entries in bwscan.20151029-1145 >> >>Tom, >> >>Looked even more closely. >> >>I flittered out all relays that are >>not currently active, ending up with >>a list of 6303 live relays. >> >>1065 or 17% of them have not be >>updated for five or more days, >>292 or 4% have not been updated >>for ten days, and 102 or 1% >>have not been updated for 15 >>days. >> >>In particular I know of a very fast >>high quality relay in a CDN-grade >>network that has not been measured >>in 13 days. My relay Binnacle >>is a well run relay in the >>high-quality Verizon FiOS network >>and has not been measured for 10 days. >> >>This does not seem correct. >> >> >>P.S. Here is a quick list of some >>top-30 relays that have have been >>seriously neglected: >> >>redjohn1 10/9 >>becks 10/15 >>aurora 10/20 >>Onyx 10/14 >>IPredator 10/15 >>atomicbox1 10/21 >>sofia 10/14 >>naiveTorer 10/15 >>quadhead 10/12 >>3cce3a91f6a625 10/13 >>apx2 10/14 >> >> >> >>>At 13:35 10/29/2015 -0400, you wrote: >>> >>>>The system is definetly active. . . .the most recent file has ten day old entries? >>> >>>Just looked more closely. About 2500 >>>of 8144 lines (30%) have "updated_at=" more >>>than five days ago or 2015/10/24 00:00 UTC. >>> >>>Seems like something that should have >>>an alarm check/monitor. >

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