[tor-relays] Re: Tor Relay Operator Meetup at FOSDEM 2026

[Alexander Hansen Færøy via tor-relays <tor-relays@xxxxxxxxxxxxxxxxxxxx>]

Hello Tor Relay Operators!

Hope those of you who participated in the FOSDEM Tor Relay Operator meetup made 
it home safely from the event. As always, I try to write down notes from the 
meetings, but since I write them after the meeting, I have almost certainly 
forgotten a lot. Please add context that you think is missing in this email.

It's been a while since we did Tor Relay Operators meetups during FOSDEM. We 
ended up being between 30 and 40 people in the tiny, windowless room at the 
event, which was more than I anticipated. I will make sure we do a similar 
meetup at FOSDEM in 2027!

The meeting started with a short presentation from me about where we are with 
the network work. The big topics here were Post-Quantum Cryptography, the 
transition to Happy Families, the move to MaybeNot on Arti for better 
padding-state machines, Proposal 344 + Tor's threat model, and Arti Relays. The 
slides were primarily based on the slides from the 39c3 Relay Operator meetup, 
and they are available from 
https://ahf.me/talks/2026/02/01/tor-relay-operators-meetup/

Afterwards, Jules Dejaeghere from Université de Namur gave a short presentation 
on their research project, which they also wrote about on this email list. They 
are actively looking for volunteers from the Tor relay operator meetup to 
conduct interviews on operational practices for running relays in the network. I 
understood from Florentin on IRC that they had a lot of sign-ups after the 
meeting, which is fantastic. Thanks to everybody who signed up to help this 
research group. The Tor Project relies heavily on the research community, so the 
more ways we can help them the better <3

Afterwards, we had around 30 min. of Q&A. The big topics here were:

- Should Tor's path selection algorithm take into account AS-path information to 
avoid circuits transiting through similar networks in the circuit path? I 
mentioned some of the earlier papers on this work. One of them was "Guard 
Placement Attacks on Location-Based Path Selection Algorithms in Tor," and the 
other was "CLAPS: Client-Location-Aware Path Selection in Tor." For more 
information about the two, please check out https://www.freehaven.net/anonbib/

- When do we get IPv6-only relays? Probably after we have moved to Arti Relays, 
but to get to the point where we have IPv6-only middle nodes, we need all guards 
and exit nodes to have IPv6. This work can begin now. As part of this, we also 
briefly discussed how, with the transition to Arti Relay, we expect to see a 
smaller Tor network (in terms of the number of relays), but hopefully a more 
performant network.

- We talked about some problems with the deployment of Post-Quantum 
Cryptography, where we depend heavily on our dependencies being available in the 
distributions that Tor relay operators run. For the upcoming Arti Relay test 
network, we will likely experiment more aggressively with containerized 
deployments, allowing us to control more of the stack (e.g., libssl, libcrypto) 
on the release side of Tor.

- This led to a broader conversation about stateless relays and remote 
attestation. I lost a bit of track of this, but within The Tor Project, many of 
us are very excited about the work that different relay operator groups are 
doing in this space. Both stateless relays and work on remote attestation, as 
well as getting the various cryptographic keys used in the Tor network into 
transparency logs. We think this work could significantly support our Network 
Health efforts. I suggested that a nice demo here would be an Onion Service that 
allows remote attestation of the service by potentially publishing some of the 
metadata needed in the Onion Service descriptor. This entire conversation 
eventually became the big topic on the hallway track after the meeting, too. We 
also plan on making it possible in C Tor to make the Onion key easier to handle 
in the stateless relay situation.

Thanks to everybody who participated! Please let me know if there is anything we 
can do better in these meetings. Feel free to reach out if you have any 
questions that need more elaboration.

I do not know when the next Tor Relay Operator meetup will be, but I know I will 
be hosting one in the summer at BornHack 2026. I hope someone who is going to 
EMF in the UK (unfortunately at the same time as BornHack this year) can host a 
Relay Operator meetup there too!

Cheers,
Alex

--
Alexander Hansen Færøy
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