Stéphane Bortzmeyer

Based in Paris (France)




Likes on articles

About the author

I work at AFNIC (the registry of .fr domain names), in the R&D department, on, among other things, DNS, security, statistics.

• On A Review of Blockchain Applicability to Internet Number Resources by Marco Hogewoning

Saying that automatic contracts ("smart contracts" is the marketing BS) cannot be changed ("these contracts are unmodifiable") is not strictly true. To quote an old saying "every problem in computer science can be solved with one more indirection". So, you can have a pointer to the current version of the code of the smart contract, and changing the code by adding a new version of the pointer. Of course, this adds complexities and security risks but it shows that there are ways to modify automatic contracts, for instance to follow a change in policies. The description of the "51 % attack" is very sketchy ("quickly spawning a large quantity of client nodes that participate in the consensus making"). In a real blockchain, techniques like proof-of-work and proof-of-stake prevent this trivial Sybil attack. But there is a subtler reason why the "51 % attack" is overhyped: it is easily detectable (the Bitcoin Core code, for instance, logs it). So, honest miners will see it. It will not be easy to recover from the attack (the honest miners will have to fork) but it cannot be stealthy.

• On ARTEMIS: Neutralising BGP Hijacking Within a Minute by Vasileios Kotronis

The link "real-time streaming capabilities" goes to a 404. I suspect the correct target is

• On Securing DNS Across all of my Devices with Pi-Hole + DNS-over-HTTPS + by Scott Helme

I love "curl | sudo bash" in an article about security :-) Seriously, it seems the article has a confusion between DoH, as currently being standardized at IETF (and deployed by Cloudflare on and the Google service which, unlike DoH, does not use the DNS wire format, but JSON, as shown in your example.

• On Creating RIPE Atlas One-off Measurements with Blaeu by Stéphane Bortzmeyer

The first package is for Gentoo :-)

• Reply to Wouter on Creating RIPE Atlas One-off Measurements with Blaeu by Stéphane Bortzmeyer

“Looks useful, thanks for sharing this! Can you briefly comment on what features this tool offers that are not in the official command line client?”

I started its development long before the "official" CLI program existed. After that, it's a matter of choice. Can you now display aggregated results with the "official" client? Last time I tried it, it was weak on that, displaying results probe per probe.

• On Fixing Reachability to, GLOBALLY! by Marty Strong

For Orange (AS 3215), it does not seem solved yet. A lot of timeouts: % blaeu-resolve -r 1000 --as 3215 --nameserver --type AAAA --displayvalidation Nameserver [ (Authentic Data flag) 2001:4b98:dc0:41:216:3eff:fe27:3d3f 2605:4500:2:245b::42] : 129 occurrences [TIMEOUT(S)] : 84 occurrences [2001:4b98:dc0:41:216:3eff:fe27:3d3f 2605:4500:2:245b::42] : 1 occurrences Test #12196625 done at 2018-04-17T12:38:13Z

• On Using RIPE Atlas to Debug Network Connectivity Problems by Stéphane Bortzmeyer

The tools presented here have been superseded by Blaeu, available at and documented at

• On RIPE Atlas Measurement Tagging by Chris Amin

It seems a very good and useful feature. But calling it "tags" is a bad idea since it already means something else for RIPE Atlas :-(

• On RIPE Atlas Measurement Tagging by Chris Amin

The link to "RIPE Atlas API v2 manual" goes to, which times out. (It is probably an internal site.)

• On FOSDEM 2018: What Happens in Brussels (Ends Up on the Internet) by Vesna Manojlovic

@emileaben Rather than standardizing human-readable output format, why not emitting a standard structured format, separating the network part (traceroute) and the visualisation part (a tool using the structured output format). Such a format already exists, in RFC 5388. I let you do the same in JSON :-)

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