Thanks Colin Its useful to know that there are discrepancies such as this as it will save me time in relooking at my data and calculations and wondering why its isnt making sense. regards Paul ________________________________ From: Colin Johnston <colinj@mx5.org.uk> Sent: 26 March 2021 08:16 To: Mccherry, Paul (Student) <p.mccherry@lancaster.ac.uk> Cc: Robert Kisteleki <robert@ripe.net>; ripe-atlas@ripe.net <ripe-atlas@ripe.net> Subject: Re: [atlas] [External] Re: Probe location obfuscation 2317 is actually 10 miles down the east lancs rd but configuration says manchester Col On 26 Mar 2021, at 06:25, Mccherry, Paul (Student) <p.mccherry@lancaster.ac.uk<mailto:p.mccherry@lancaster.ac.uk>> wrote: Thanks Robert I am using the probe estimated geolocations to validate a new active geolocation method I am formulating. The probe I that I thought had an anomaly was in fact found to be within 1k distance of my estimated geo location using the new method. The original discrepancy was due to a number of factors that I had failed to accurately apply. However, I have other probes that have similar but different issues and whilst I am working my way through these issues any additional information you can provide would be greatly appreciated. Regards Paul McCherry Phd Student Lancaster University. ________________________________ From: Robert Kisteleki <robert@ripe.net<mailto:robert@ripe.net>> Sent: 25 March 2021 12:47 To: Mccherry, Paul (Student) <p.mccherry@lancaster.ac.uk<mailto:p.mccherry@lancaster.ac.uk>>; ripe-atlas@ripe.net<mailto:ripe-atlas@ripe.net> <ripe-atlas@ripe.net<mailto:ripe-atlas@ripe.net>> Subject: [External] Re: [atlas] Probe location obfuscation This email originated outside the University. Check before clicking links or attachments. Hi, On 2021-03-25 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.
We don't have strict rules about precisely how the hosts should geolocate their probes -- and could not enforce those even if we had them. Instead we recommend doing this "roughly correct", which for some hosts means city / neighbourhood is good enough, for some others it's the exact spot of the utility box at home :-)
I am a Phd student carrying out research on the RIPE atlas platform and an early result seems to indicate 1 probe has an obfuscation of 10km distance but this may be an anomaly or perhaps something not taken into account as yet.
We have a very simple algorithm that does the obfuscation consistently with a certain maximum distance added, which may not be precisely 1km. We can talk offline about the details if you're really interested in the precise method. Cheers, Robert