They have registration data. Someone could declare they don't want IPs registered to companies from Frankfurt with geofeeds in Frankfurt to be advertised in Dubai.

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sgjohnson 2 hours ago | parent [-]

It’s not how any of it works.

How do you determine to whom an IP is even registered to? They get sub-leased all the time.

The best you can do is check who has administrative control over the prefixes RIR info, but that doesn’t mean that anyone with control is the factual user of the IPs.

You could check the IRR for the ASN and base it on that, but still.

There's also no way to actually know _where_ an IP actually originates from. Only its AS path.

The DFZ contains all prefixes announced everywhere, for the internet is completely decentralized.

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pocksuppet an hour ago | parent [-]

> How do you determine to whom an IP is even registered to?

You check the RIR's records.

> They get sub-leased all the time.

With records updated. If not, any consequences from wrong information fall on the lessor and lessee.

> There's also no way to actually know _where_ an IP actually originates from. Only its AS path.

Ping time from different locations on their upstream AS gives a good guess.

	▲	sgjohnson 23 minutes ago \| parent [-]
		> With records updated. If not, any consequences from wrong information fall on the lessor and lessee. Not always + there are no consequences whatsoever. Plenty of leasing services will just provide you with IRR & RPKI, without ever touching the actual records. > Ping time from different locations on their upstream AS gives a good guess. Upstream AS is meaningless if it's a T1 carrier. Ping AS6939. They are everywhere.