- tor-relays - lists.torproject.org

'relay early' attack detection at the infrastructure level
by Nusenu 02 Aug '14

02 Aug '14

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 [moved to tor-relays] Hi relay ops, please consider having a regular look at your logs after upgrading to the latest tor releases to spot relay_early attacks (even if the attack origin is not directly attributable from a relays point of view). searching your logs for 'Received an inbound RELAY_EARLY cell' should do it. https://gitweb.torproject.org/tor.git/commitdiff/68a2e4ca4baa595cc4595a511d… >>> It doesn't have to decrypt the stream to see it, because >>> whether a cell is relay or relay_early is a property of the >>> (per hop) link, not a property of the (end-to-end) stream. >> >> Does a patched relay also create a log entry as soon as it >> "kills" the circuit or is logging only happening on tor instances >> acting as clients? > > The patched relay also does a log message, yes. > > But the relay can only see its immediate neighbor in the circuit, > so it will only log that. Whether the attacking relay is that > (adjacent) one, or one farther on the circuit, isn't something your > relay can learn. -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJT3Bt6AAoJEDcK3SCCSvoensYQAJnuXhPNbhdJF7C6P9L8elG7 elPinCK6vmTbRXCoQam5j1VeL9C3FCBv415s811hfZxA37K17VdiKoS1NXB2kzkW 7WvL5/lH8culr83GTxrca0m7i2x6n0gCPOVPUWI3Go5bzwlsEidZsj7V14h2lfXH Ew8ZavvL0SLnRYJTvcjzqrWf3L8LsfYou6R2Y7yn085rGaGtUyVkQM44G9Zy3TVY 3lS4XqkZekXmmKjP06JjWdFMFdkaQhItbcdn3fF131ptlZlM5hFUaEpZHbpLLcjz fgJOt36jlkfILKRvxGyzcI118wmgrFVJFz9d7fuLVOdekK49aWxKh9Yh2aAekQEn Z3uF/eskL+Txptrc7iEKuWQZVlEkA8WVaQ70F1ADD/irln6ShJ17zrKqJ0qtaYlU V+CNfj/v2R6AgRhbVsNRdq8SWhDz4Nk4WgdYoUvxzgM1jmkAhQamlkC4f6JCqVQE /O0qeuXr/Z02pBwshcZlqKnBmPtuilSZwmlstIEfPAX9Tg6S1a0B/ycp3ByyJHJP QUNKwJ/cHtLpdPmIh2XUOT/5Kf10qmrLP5amYdRtBh304GoeHir3N/zfPmxdLfy7 Spb8W4p2C1HITzRlb9J97OGdKOR/2OOziZHOWZimF5O3fsrzsXQZe3Wlwbt5AxtY LJ5aXCUjNJ/TXe93nSQH =3FwX -----END PGP SIGNATURE-----

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More attack traffic against Tor detected on exit relay
by tor＠t-3.net 01 Aug '14

01 Aug '14

IPTables rule involved: -A INPUT -p tcp -m string --hex-string "|00002800390038008800870035008400160013000a00330032009a009900450044002f00960041000500ff020100000400230000|" --algo kmp -j LOG --log-prefix "IPTables-GFC-new " -A INPUT -p tcp -m string --hex-string "|00002800390038008800870035008400160013000a00330032009a009900450044002f00960041000500ff020100000400230000|" --algo kmp -j DROP Logs generated Wednesday from hits against these rules: Jul 30 13:44:38 Libero2-vserver kernel: IPTables-GFC-new IN=eth0 OUT= MAC=00:16:3e:21:6d:34:00:21:d8:25:c0:20:08:00 SRC=1.50.250.198 DST=64.113.44.206 LEN=147 TOS=0x08 PREC=0x20 TTL=44 ID=21838 DF PROTO=TCP SPT=13717 DPT=9001 WINDOW=46 RES=0x00 ACK PSH FIN URGP=0 Jul 30 13:44:59 Libero2-vserver kernel: IPTables-GFC-new IN=eth0 OUT= MAC=00:16:3e:21:6d:34:00:21:d8:25:c0:20:08:00 SRC=175.152.3.46 DST=64.113.44.206 LEN=147 TOS=0x00 PREC=0x00 TTL=50 ID=21839 DF PROTO=TCP SPT=49229 DPT=9001 WINDOW=46 RES=0x00 ACK PSH FIN URGP=0 Jul 30 13:45:41 Libero2-vserver kernel: IPTables-GFC-new IN=eth0 OUT= MAC=00:16:3e:21:6d:34:00:21:d8:25:c0:20:08:00 SRC=124.90.49.99 DST=64.113.44.206 LEN=147 TOS=0x00 PREC=0x00 TTL=49 ID=21840 DF PROTO=TCP SPT=10200 DPT=9001 WINDOW=46 RES=0x00 ACK PSH FIN URGP=0

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don't worry (to much) if your relay is loosing the guard flag
by Nusenu 01 Aug '14

01 Aug '14

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 I guess it makes sense to make this change a bit more visible on the tor-relays mailing list since relay ops will notice the change eventually and not everyone is reading changelogs closely. A lot of relays will loose their guard flag (and probably see less traffic?) once enough dir auths [1] upgraded to 0.2.5.6-alpha. For the background see the changelog [2]: >> o Minor features: - Authorities now assign the Guard flag to the >> fastest 25% of the network (it used to be the fastest 50%). Also >> raise the consensus weight that guarantees the Guard flag from >> 250 to 2000. For the current network, this results in about 1100 >> guards, down from 2500. This step paves the way for moving the >> number of entry guards down to 1 (proposal 236) while still >> providing reasonable expected performance for most users. >> Implements ticket 12690. It will be interesting to follow the metrics graphs during that transition. I.e. will the guard bw history go down or will the remaining relays handle the same amount of traffic without any difference? (and similar questions) https://metrics.torproject.org/bandwidth.html#bandwidth-flags [1] https://consensus-health.torproject.org/#authorityversions [2] https://lists.torproject.org/pipermail/tor-talk/2014-July/034180.html -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJT2rO6AAoJEDcK3SCCSvoeh4sP/iH6DKlOLtCo1ZoBYKsZx+EJ jir+Lk4urwU+3MeM5Ikbb/XTCXY9Y3RCX8tTG65tn+NoLKNJP/fUGuz8A87Vrc48 ismcoSPrjpgX358VMLy7gO9i1tZGLGDd6qNuh0hLws1Z1JVMBACQKv6ZJrSuaoy6 gM/+htBawyRy8KC9Lsw4C6RZsu8b5Kintn9D6MmcWwVIDY8voB3wyypeZZLWaFzI N9sfyT9M4GC+i2CyWsYNdXB/x6z+IEsq0FE0XMdaLr0W17vh8pef0X3XH06h+MUf GsqK86MkjiYfQ0KfMkA/XfYCA3AWTdMSn63L40cDtLqBEHILlvpY/awWX0G78cnU D6cyhRs/R9rUlzvxMxtEF2mMrhvMAkWhz3JrqoEh0o6eOOF9QsOB700rovNsNufw tCYw/PfDD8PVj/J38jcidxo4VBtLcIrdnSInFuLezyZtvKvlCgzMomu8fOdSLxgf gXmKLY6MzduQFAqgYOg5eu33zMSqiTckC2mWPJXWiJ8m5uRbgw57I+7DjTalB4lD KTBTbtjLf+jbZOYn+E8bmoi8hQFPfhjkMMaqSIXeooqDa2xTbYlmEgPy4VmW5rLf cJd1rM2irw9yMKIYMMcI/aLG5uWZJ5pYAw0zWNA1aBzp33mgJ1yFbdhk9BMA+3/G rqNAV1pSC4brVzn4nF++ =02Sf -----END PGP SIGNATURE-----

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tor daemon problem with obfsproxy
by Fereydoon Sepehri 01 Aug '14

01 Aug '14

Hi All, I install and configure tor to set up a obfs3 bridge. If I use command "tor", everything is fine and clients could connect to server buf if I use "service tor start", the connection will be refused. I checked the log file. the problem is: [warn] The communication stream of managed proxy '/usr/bin/obfsproxy' is > 'closed'. Most probably the managed proxy stopped running. This might be a > bug of the managed proxy, a bug of Tor, or a misconfiguration. Please > enable logging on your managed proxy and check the logs for errors. > Jul 31 20:55:56.000 [notice] Failed to terminate process with PID '28836' > ('No such process'). the question is why "tor" command could run the obfsproxy but "service tor start"could not. I change the permission of "obfsproxy" from "root" to "debian-tor" but it did not solve the problem. Best Regards Fereydoon

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Re: [tor-relays] obfsproxy issue
by Mike Patton 01 Aug '14

01 Aug '14

On 01/08/2014 3:00 am, Fereydoon Sepehri <fereydoonsepehri(a)gmail.com> wrote: > > Dear All, > > I want to set up tor Bridge. the bridge is up and working normally. > I decided to use obfsproxy to set up obfs3 bridge. > > I installed Python, python-pip and obfsproxy. > the obfsproxy is in "/usr/bin/" directory. The "obfsproxy which" command did not show this directory but this: > -bash: /usr/local/bin/obfsproxy: No such file or directory > > could you please advise me on this issue. > > Best Regards > Fereydoon As a suggestion, perhaps take the error meager as instructive? Try putting obfsproxy in /use/local/bin instead of /use/bin. M.

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obfsproxy issue
by Fereydoon Sepehri 31 Jul '14

31 Jul '14

Dear All, I want to set up tor Bridge. the bridge is up and working normally. I decided to use obfsproxy to set up obfs3 bridge. I installed Python, python-pip and obfsproxy. the obfsproxy is in "/usr/bin/" directory. The "obfsproxy which" command did not show this directory but this: -bash: /usr/local/bin/obfsproxy: No such file or directory could you please advise me on this issue. Best Regards Fereydoon

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Auto Response
by bbzxrmy wowman 31 Jul '14

31 Jul '14

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how sensitive is relay 'state' file?
by starlight.2014q3＠binnacle.cx 31 Jul '14

31 Jul '14

Can anyone comment on how sensitive the information in the relay 'state' is? In particular, if entry guards are recorded in the file should one be concerned about protecting the file via a) encrypting the file system where it resides b) making a point of not backing up the file I suppose it comes down to how likely it is that an adversary can use entry guard information for correlation attacks against past and present tor-client traffic originating from a targeted client-relay.

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Finding relay Sybils / Groups [re: relay_early/blackhat]
by grarpamp 31 Jul '14

31 Jul '14

As a project then to production development, someone should go back through the entire history of descriptors and look for groups coming online... dates, IP's, contacts, tor/OS versions, nicknames, ISP's, geoip, numbers coming online over sliding timeframes, correlation to 'news events', etc. There may be more questionable relays to be found. We were talking about such influxes around july 4 09, ironically, or not.

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German company Webtropia: Terminated contract without notice because of abuse
by tor＠t-3.net 31 Jul '14

31 Jul '14

You somewhat made a mistake here - you've got to have an exit policy that (minimally) rejects ports 25 and 465, or else your relay becomes a giant abuse tool for spammers, scammers, and phishers instead of what you intended it to be (which was a standard-functioning Tor relay). You might try telling your ISP that you made a mistake in your configuration which allowed spam email to go out, and you're willing to correct that error and move forward. ExitPolicy reject *:25 ExitPolicy reject *:465

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