crackthe.net

Method

What is measured

For every location a provider publishes, crackthe.net keeps what the provider’s own server list says about it. For a rotating sample of locations it pings one published server endpoint from probes in many countries and stores every reply with probe, time and method version.

What latency can show

A reply that takes r milliseconds for the round trip cannot come from farther away than r × 100 km. Light in fibre covers about 200 km per millisecond, and the round trip covers the distance twice. Real routes are longer than the direct line, so the endpoint is usually much closer than this bound.

The check works in one direction only. A fast reply from a distant probe rules a location out. A slow reply rules nothing out, and no reply proves a location.

What a reply can do besides ruling a place out is tie the server down. A server within r km of a probe that stands g km from the listed country is at most r + g km from that country. “Compatible” means this distance is small. It never means “confirmed to be there”.

Rules

  1. A probe rules a location out when it is farther from the claimed country than its reply allows, with 100 km added for imprecise probe positions. Where the provider publishes city coordinates, the same test runs against a 50 km circle around them.
  2. A location is “incompatible” only when at least 2 probes in different networks or cities rule it out.
  3. Probes whose stated position contradicts the others are discarded. Two probes that both reach the same endpoint cannot be farther apart than their two bounds combined; where that happens, the probe involved in the most contradictions is dropped.
  4. A location is “compatible” only when no probe rules it out and the closest reply places the server within 1,000 km of the listed country. Where no probe is near enough for that, the result is “no statement possible”.
  5. One run is an observation. It counts as confirmed once a second day shows the same.

What is measured first

Locations are measured in turn, but not in arbitrary order. First come those where a finding would say something the provider’s list does not: lists that have no virtual marker, then locations a marking list leaves unmarked, then locations the provider marks virtual itself. Where a location’s addresses lie next to those of a location the same provider lists in another country, probes in that country are asked as well. When a location is ruled out, the path to it is traced from the nearest probe, and the last routers on it that give a name are shown with the result.

Networks

For every published endpoint the site also records which network announces its address on the internet. This comes from a public routing table, not from a measurement of our own. The country shown with a network is where the network is registered, which says nothing about where a server stands. What the table does show is which providers place servers with the same operators.

Limits

  • Measured is the published server endpoint, not the address traffic leaves from. Confirming the exit needs an account with the provider.
  • Claims are checked at country level, and at city level only where the provider publishes coordinates. Regions inside one country, such as US states, are not told apart.
  • Most probes stand in data centres, and their positions come from IP geolocation.
  • Country outlines are drawn at 1:50 million scale. Small islands near a coast can be missing.

Using the data

The figures on this site, and the JSON files that carry the same figures, may be quoted and reused with a visible credit to crackthe.net and a link to the page they come from. Published are the current state and the changes of the last three months. The measurement history behind them is not published.

Sources

  • Server lists: each provider’s own public list, linked on the provider’s page.
  • Probes: Globalping.
  • Country outlines: Natural Earth, public domain. Country names: Unicode CLDR.
  • Networks: iptoasn.com, public domain.