[atlas] List of Atlas probes subjected to DNS traffic interception (MITM)

On Fri, Sep 29, 2017 at 02:56:12PM +0200,
 Baptiste Jonglez <baptiste.jonglez at imag.fr> wrote 
 a message of 56 lines which said:

> What I mean by "traffic interception" is that DNS queries from the
> probe to a third-party DNS server do not reach the server, but are
> intercepted and answered by a middle-box instead.

Many interceptors (for instance the GFC) do so only when the request
matches some criteria. "Intercepting" is not all-or-nothing.

> It seems that the "DNS Root Instances" map could be used for that purpose,
> because DNS traffic interception shows up as if the probe was contacting
> an "Unknown" root instance.

There are many rogue root instances (with anycast, it can be difficult
to be sure of talking to a real root) so a strange instance is not
always DNS interception.

> I also looked for DNS-related tags on probes, but could not find
> anything useful.

System tag "clean DNS" would certainly be useful but, as the two
examples above show, it is difficult to define precisely.