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Tor from Telmex. When I say "achievement unlocked", I mean it!

The blockade has ended! For some introduction..

Back in 2016, Telmex –Mexico’s foremost communications provider and, through the brands grouped under the América Móvil brand, one of Latin America’s most important ISPs– set up rules to block connecitons to (at least) seven of Tor’s directory authorities (DirAuths). We believe they might have blocked all of them, in an attempt to block connections from Tor from anywhere in their networks, but Tor is much more resourceful than that 😉 so, the measure was not too effective.

Only… Some blocking did hurt Telmex’s users: The ability to play an active role in Tor. The ability to host Tor relays at home. Why? Because the consensus protocol requires relays to be reachable –in order to be measured– from the network’s DirAuths.

Technical work to prove the blocking

We dug into the issue as part of the work we carried out in the project I was happy to lead between 2018 and 2019, UNAM/DGAPA/PAPIME PE102718. In March 2019, I presented a paper titled Distributed Detection of Tor Directory Authorities Censorship in Mexico (alternative download in the Topic on Internet Censorship and Surveillance (TICS) track of the XVIII International Conference on Networks.

Then… We had many talks inside our group, but nothing seemed to move for several months. We did successfully push for increasing the number of Tor relays in Mexico (we managed to go from two to eleven stable relays — not much in absolute terms, but quite good relatively, even more considering most users were not technically able to run one!)

Jacobo Nájera, journalist participant of our project, didn’t leave things there just lying around waiting magically for justice to happen. Together with Vasilis Ververis, from the Magma Project, they presented some weeks ago a Case study: Tor Directory Authorities Censorship in Mexico.

Pushing to action

But a good part of being a journalist is knowing how and when to spread the word. Having already two technical studies showing the blocking in place, Jacobo presented his findings with an article in GlobalVoices: The largest telecommunications operator in Mexico blocks the secure network. Surprisingly (to me, at least), this story was picked up by a major Mexican newspaper: The same evening the story hit GlobalVoices, Rodrigo Riquelme posted an article, in the Technology section of El Economista, titled Telmex blocks seven out of ten accesses to the Tor network in Mexico. And that very same day, Telmex sent a reply I am translating in full (that is now included at the end of Riquelme’s article):

Mexico City, May 28, 2020

In relation to Tor navigation from TELMEX’s network, the company informs:

In TELMEX, we are committed to the full respect to navigation freedom for all of our users.

TELMEX practices no application-level blocking policies; the Tor application, as well as the rest of Internet applications, can be freely accessed from our network.

In order to protect the Internauts’ information, the seven refered nodes were in their time reported because they were associated with the distribution of the WannaCry ransomware, which is the reason they were filtered, but this does not hamper the use of the Tor application.

So we got an answer…?

Jacobo knew we had to take advantage of this answer, and act fast! He entered rush-writing mode and, with the help of our good friend and lawyer Salvador Alcántar, we wrote a short letter to Renato Flores Cartas, Corporative Communication of América Móvil, and sent it on June 1st.

Next thing I know, this evening Jacobo was asking me if I could confirm the blocking was lifted. What‽‽‽ I could not believe it! But, yes — Today Jacobo published the confirmation that the seven blocked IP routes were finally reachable again from ASN 8151 (UNINET / Telmex / América Móvil)!

Of course, this story was picked up again by El Economista — Telmex unblocks IP addresses for the Tor network’s directory authority server IPs in Mexico.

Wrapping up

How can I put this in words? I am very, very, very, very, very, very, very, very, very happy we managed to see this through!

Although we have been pushing for increasing the usage of Tor among users at risk in Mexico — Being a journalist, defending human rights, are still a high-risk profession in my country. We strongly believe in this, and will continue trying to raise awareness of the usage.

But, just as with free software, using network anonymization tools is not all. We need more people to become active, to become engaged, to become active participants in anonymization. As the adage says, anonymity loves company — In order to build strong, sufficient anonymization capability for everybody that needs it, we need more people to provide relay services. And this is a huge step to improve Mexico’s participation in the Tor network!

Image credits: Seeing My World Through a Keyhole, by Kate Ter Haar (CC-BY); Tor logo (Wikimedia Commons)