IPv4 leasing often gets dismissed as too risky by the people who actually hold the blocks. The concern usually sounds like this: "What if I can't get it back?"
Here's the short answer: you can. Here's the structural explanation of why.
Ownership lives in the registry. Routing lives in the config.
When you hold an IPv4 block, what you actually hold is an RIR registration — a WHOIS record that names your organization as the resource holder. That record does not update when someone else starts routing your space. BGP announcements change. Your registration does not.
A lease grants routing authority. That's it. The lessee can originate traffic from your addresses for the duration of the agreement. They cannot sublease without authorization, hold the block past expiry, or acquire any RIR standing over the space. RIPE, ARIN, and APNIC classify leasing as a utilization arrangement — not a transfer event.
The two controls that actually matter
LOA (Letter of Authorization) — the document you sign to allow routing. No valid LOA, no routing. Revoke it and the upstream provider pulls the announcement, typically within 24–72 hours. This requires zero cooperation from the lessee.
RPKI / ROA — you cryptographically authorize which ASN can originate your prefix. Revoke the ROA and RPKI-validating routers reject the announcement at the network level, not just contractually. This is the part most owners don't know about — it's a structural control, not just a legal one.
What reclaiming actually looks like
Revoke or expire the LOA
- Update the ROA to deauthorize the lessee's ASN
- Confirm de-announcement via looking glass
- Run blacklist checks before reuse
Full sequence: typically two to five business days.
The bigger picture
IPv4 space is a finite, appreciating asset. Blocks that sit idle are a capital efficiency problem. The protections described above exist precisely because the market has matured around lessor interests — they're not theoretical, they're the operational baseline.
Full breakdown with contract term requirements and reputation management, you'll find here.
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