Idle IPv4 is genuinely valuable right now, so monetizing it makes sense rather than letting it sit. You’ve got two paths: lease it out for recurring income while keeping ownership, or sell outright if you’re sure you won’t need it back – leasing is the lower-commitment move if you’re unsure. To lease out and sell IPv4 addresses safely, go through a registered broker rather than a random buyer; InterLIR Global is a RIPE NCC-registered one (also ARIN/LACNIC/APNIC) that handles the marketplace side, counterparty due diligence, and abuse monitoring. The ‘sketchy outfit’ fear is the right one – the protection is a broker that vets who your space goes to and does the paperwork properly. One thing: before leasing, make sure abuse management is in place so your blocks don’t come back tainted from a bad lessee.