- tor-relays - lists.torproject.org

Protecting Tor Circuit path selection from correlation attacks by an autonomous system
by Nathaniel Suchy 28 Aug '18

28 Aug '18

This thread continues the broader discussion of Tor Circuit path selection discussed at https://lists.torproject.org/pipermail/tor-relays/2018-August/015994.html regarding possible correlation attacks by an autonomous system. *Current measures include:* * Preventing two relays from the same /16 in IPv4 and /32 in IPv6 networks, from being in the same Tor circuit. CIDR is helpful, but is it enough? * The MyFamily directive, this does rely on relay operators being honest and we shouldn't rely on this as the sole indicator. * Others things that I am not aware of? *Some measures worth considering include:* * Preventing two relays in the same ASN from being in a circuit. * Maybe prevent two relays in the same ASN from being Guard and Exit, excluding the middle relay from this calculation. * Bridges could be a challenge when implementing this, although it's not impossible. * Looking at relays with same/similar names, heuristics maybe? It's really guesswork but hey it might work. * Looking at relays with same/similar contact info * Looking at relays in the same geographic regions and avoiding them * Relays with the same non-standard ports - excluding 9001, 9030, 80, 443 (anything else that's super common?) * On device models looking at the above data to make decisions of which relays are most likely run by the same entity, use machine learning to make an informed decision based on all factors maybe? *Papers worth reviewing:* * AS-awareness in Tor Path Selection https://www.freehaven.net/anonbib/cache/DBLP:conf/ccs/EdmanS09.pdf * Users Get Routed: Traffic Correlation on Tor by Realistic Adversaries https://www.ohmygodel.com/publications/usersrouted-ccs13.pdf * Moving Tor Circuits Towards Multiple-Path: Anonymity and Performance Considerations https://pdfs.semanticscholar.org/aa94/7dd4762bd0f6531bacfeac9d29ef1e1d4cd6.… * Avoiding The Man on the Wire: Improving Tor’s Security with Trust-Aware Path Selection https://www.nrl.navy.mil/itd/chacs/sites/www.nrl.navy.mil.itd.chacs/files/p… *Outside the scope:* * In AS-es where Virtual Machines are sold, and Physical Machines are not. It's quite possible that the provider may steal relay keys. Little research exists where you could successfully protect against such an adversary who isn't playing nice. Legislation (For example, GDPR) in the EU exists where such activity may violate local laws. This may or may not be enough. Certainly not against a government actor, but against an AS doing it per their only devices maybe. * An AS hosting a Tor relay who logs or watches network traffic will always be able to learn something about the circuit, but perhaps we can prevent them from learning everything about the circuit most of the time. Everyone on the list has a had very insightful and helpful thoughts on this discussion so far and I'm looking forward to getting more discussion of the broader issue. Cordially, Nathaniel Suchy

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Avoiding Off-Topic Posts
by teor 28 Aug '18

28 Aug '18

Hi, A healthy, robust, and growing tor network needs a lot of different ways to run tor relays. Focusing on one or two models creates single points of failure. So we encourage individual volunteers, organisations, donations, paid services, and researchers: as long as they operate ethically and prioritise user safety. That said, this list is for "support and questions about running Tor relays". In future, please: * keep on topic, we are here to help each other run Tor relays * make sure each post contains new, useful information. You can search the archives before posting: https://lists.torproject.org/pipermail/tor-relays/ * avoid promoting or criticising the same providers more than once a month * deal with commercial / payment issues off-list But you should feel free to ask questions about operating relays at any time. T -- teor Please reply @torproject.org New subkeys 1 July 2018 PGP C855 6CED 5D90 A0C5 29F6 4D43 450C BA7F 968F 094B ----------------------------------------------------------------------

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Issues regarding 185.125.33.114 relay
by Nathaniel Suchy 27 Aug '18

27 Aug '18

Can the operator of the relay 185.125.33.114 please reach out to me? There is not any contact information available on Tor Metrics for the relay. Cordially, Nathaniel Suchy

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Congrats to Nullvoid
by Conrad Rockenhaus 27 Aug '18

27 Aug '18

I just wanted to say congratulations to Nullvoid, who is currently running the second fastest exit in France in my colo in Europe. https://metrics.torproject.org/rs.html#details/51420DFB2047A33803A9A6E456D6… Also, go FreeBSD! Thanks, Conrad

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Re: [tor-relays] Individual Operator Exit Probability Threshold
by livak 25 Aug '18

25 Aug '18

Hi ! In a an older thread I read: > Like Teor mentioned, it's important for operators to increase capacity > and stability, while still meaningfully supporting diversity. Emerald > Onion is not going to surpass 10% of exit capacity without first > helping ~10 other groups set up and manage their own 1%+ relays. As > more and more high-capacity groups come online, I think orgs like > Quintex and Emerald Onion can slowly increase capacity but stick > around the 10% line. Is there any help for setting up new high capacity exit relays ? Livak Sent with [ProtonMail](https://protonmail.com) Secure Email.

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Yay, Complaints
by Conrad Rockenhaus 25 Aug '18

25 Aug '18

So, new equipment gets plugged into a colo…. I’m a dude that was looking to increase AS diversity on Tor and well, decided to add a new colo to the mix. Two exit relays are brought online on properly SWIPed IP addresses. These exit relays have only been online for about 24 hours. An organization, known as Irdeto Intelligence, ignores the fact that the IP addresses are SWIPed and sends abuse complaints to my upstream providers asking them to straighten me out, because I’m a pox on society because people are torrenting via Tor. They have sent over 40 emails in the last 12 hours. Some dude-man, who calls himself a “Network Security Administrator” who asked me to explain what Tor is……….because he’s a Network Security Administrator……..has told me that due to the volume of complaints I need to block the offending applications from their network. I told him that I spoke with them prior to bringing this stuff online, explained what Tor was, explained what a Tor exit was, explained that it will generate complaints, explained the DCMA liability, explained the whole thing…..and was told that they were okay with it. I’m sorry for the bitching and moaning…it’s just another case of doing everything right and now I’m quite worried that they’ll not only pull the plug, that I’ll have to fight to get my Cisco UCS blade server back (and other assorted equipment) which is totally not going to be cool. Conrad

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Freebsd trial with greypony.it was a success
by zimmer linux 24 Aug '18

24 Aug '18

Hi, Conrad Rockenhaus - with your guidance and support with freebsd, within just 21 days total running time, you have helped me set up and manage the fastest exit relay in all of Canada. See https://metrics.torproject.org/rs.html#search/country:ca%20flag:exit https://metrics.torproject.org/rs.html#details/D9B1E08CC91F7F42EEE5578EA8B0… Give yourself a pat on the back. If anyone wants to talk through running a freebsd relay, feel free to contact me off list. Zim

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Snowflake PT
by Nathaniel Suchy 24 Aug '18

24 Aug '18

Hi everyone, Tor Browser 8 Alpha includes the Snowflake PT as it comes near a final release, the adoption and usage of the Snowflake PT will continue to rise. I now have the following questions... 1) Will a command line tool like an obfs4proxy come out so those of us with infrastructure can run high capacity snowflake bridges. 2) Is the goal to replace OBFS4 with Snowflake or will they continue to co-exist? 3) How does Snowflake attempt to obfuscate, if at all it's traffic? How strong is the cryptography compared to obfs4proxy Looking forward to learning more about this :) Cordially, Nathaniel Suchy

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Dropping packets with TCP MSS=1400 to foil GFW active probing
by David Fifield 22 Aug '18

22 Aug '18

A paper from FOCI 2018 by Arun Dunna, Ciarán O'Brien, and Phillipa Gill on the subject of Tor bridge blocking in China has this interesting suggestion (Section 5.2): https://www.usenix.org/conference/foci18/presentation/dunna To do this, we write a series specific rules using iptables in order to drop packets from Chinese scanners. ... We use a rule to drop incoming Tor packets with an MSS of 1400. Further investigation would be needed to analyze potential false positives... We note that this method of dropping scan traffic successfully keeps our bridge relays from being blocked and allows our client in China to maintain access to the bridge. Like https://github.com/NullHypothesis/brdgrd, surely this trick won't work forever, but if you're setting up a new bridge, it's worth a try? This is completely untested, but I think the iptables rule would look something like this: iptables -A INPUT --protocol tcp --dport [your-bridge-port] -m tcpmss --mss 1400 -j DROP Then, after a while, check /var/lib/tor/stats/bridge-stats and see if you have any connections from "cn".

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Interested in running a FreeBSD Relay on Cogent?
by Conrad Rockenhaus 21 Aug '18

21 Aug '18

Would you like to trial a FreeBSD Relay on Cogent until October 1st? Yes, it has to be FreeBSD, because I use Bhyve as my hypervisor and some of my blades don’t support UG, which means, I support FreeBSD only on these series of servers. If you’re interested in a Model “A” (25GB HDD, 1vCPU, 2GB RAM, burstable up to 1gbit of bandwidth/unlimited transfer) running FreeBSD and would like to try it out until October 1st, just send me your Public Key. My hope is you will keep it online and hopefully increase the BSD Relay percentage to 7%. After October 1st its only $15/mo, which is my costs alone. You don’t have to worry about abuse complaints, I handle that for you. You just worry about running your exit and maintaining your OS. I take care of everything else. If you’re interested, send me a public key. Thanks, Conrad

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