More than a year ago I have started some statistical work to flag probes
with likely incorrect geolocation. Unfortunately higher priority work
has taken precedence since. I would make time to share and explain what
I have done so far if someone were to convince me that they had serious
intentions to progress the work.
Daniel
On 25 Mar 2021, at 14:02, Massimo Candela wrote:
[possibly OT]
In 2018 we found 18 probes which were located so far from reality that
the collected RTT towards targets of known locations was faster than
the speed of light (I remember we did something about those). I
suspect there are some cases more, just below speed of light. But not
so many, I believe the vast majority of the probes are all set
properly.
With software probes there is also the problem of less users reporting
a location at all (I don't have numbers, based on an observation in a
past experiment. It may no longer be the case).
I don't remember if there is something similar already in place, but I
would suggest a process like:
- if a probe doesn't have a location, set a location calculated by
latency measurements AND ask the user to review the result at is first
convenience;
- for all the probes currently having a location, use latency
measurements to mark the one possibly wrong and ask the user for
update.
- overall, use latency measurements to periodically review the probe's
location. RTTs can be used to mark obviously wrong locations, without
being too restrictive.
For RTTs above a certain amount (the usual 10ms?), deactivate the RTT
validation so users are still able to place probes in exotic
locations.
I don't think there is a use case for obfuscating probes more than at
the city level. And if there is, these probes should be tagged as
such.
Ciao,
Massimo
On 25/03/2021 13:00, Ponikierski, Grzegorz via ripe-atlas wrote:
I would add to it additional problem that some hosts obfuscate probe
location even more. For example you can find probes which in reality
are located in US but are marked as CN or probes which are in reality
in Wisconsin but are marked in California. Of course these are
extreme cases. I guess most hosts just put a pin with probe location
just somewhere around where it's locate as long it's in the same
city. I don't remember, as a host of 3 probes, to get any precise
recommendations how to mark probe location. Personally I just put a
pin in city district where probe is locate.
Regards,
Grzegorz
