Free IPv4 addresses are about to run out. The regional registries (RIRs) have few blocks of addresses left; the Asia-Pacific registry (APNIC) already has stopped regular allocations and reserves the remaining addresses for small allocations to new companies. Some reserves are left from the early days of the internet when address allocations were made more generously than today. Users of these addresses may not actually need them anymore, but had little motivation to return them to the RIRs. This site offers a free market for IPv4 addresses, allowing resource holders that don't need them anymore to sell or lease them to operators who are short of addresses.

This marketplace is organized similar to a stock exchange: resource holders can place offers to sell or lease address space, and service providers can bid for this address space. The trading price is determined for each of the service regions, separately for sales and leases. In addition, addresses that are offered for sale across regions are traded at a separate price.

The RIRs have anticipated this situation for a long time, and have changed their policies to allow explicit transfer of addresses between local registries (LIRs) within their respective service region (Africa - draft policy, North America, Asia Pacific, Latin America and the Carribean, and Europe). Policies vary somewhat across region. Transfer across regions is currently not supported by the policies, but changing policies in this respect is under discussion. Certain aspects are unregulated; for example, whether or not legacy (pre-RIR) allocations can be transferred across regions is a gray zone.

The IETF has worked on introducing IPv6 precisely to prevent the situation that is occurring now: if all had went well, we would be using IPv6 in the internet, and there was no address shortage. Many reasons have been discussed for this lack of acceptance; many believe that the absence of economic forces has caused users to ignore IPv6. With the actual exhaustion of the IPv4 space, this may change. We believe that the development of the market price for IPv4 addresses will determine whether users move to IPv6 or not.

Some people believe that a more efficient allocation of IPv4 addresses can actually resolve the shortage. In that case, the motivation to migrate to IPv6 may remain as low as it is today. Others believe that there is no reason why the exponential growth that the internet has seen would suddenly stop (although the growth likely slows down in the long term). Many devices (e.g. mobile phones) could make good use of a global IP address, and many people in the world still have no internet connectivity. In many organizations, there is a significant cost associated with freeing up "unused" addresses, so those users won't act until the price is right.

Perhaps. The RIRs already have policies in place requiring resource applicants to explain how they use the resources they were allocated in the past. These policies have indeed led to the return of unused resources (in particular in the ARIN service region). The recent policy changes indicate that RIRs rather anticipate an economic temporary solution, with the migration to IPv6 eventually resolving the address shortage for good.

RIR policies vary on whether they explicitly support leasing of IP addresses. From a network maintenance point of view, it is important to know who is using an address block at any time; whether or not there is a lease agreement is not actually relevant for the operation of the internet.

At the moment, the following policies are in force:

• Afrinic (draft policy): Legacy addresses can be freely transferred. Regularly allocated addresses can only be transferred to AfriNIC members. No special provision for leasing; no policy preventing reverse transfer after lease expiration.
• APNIC (Sect 3 of transfer policy: No special provision for leasing. A policy saying that the source party is not eligible for receiving addresses for a period of 12 months is irrelevant here, since APNIC's IPv4 space is already exhausted.
• ARIN (8.3): No special provision for leasing; no policy preventing reverse transfer after lease expiration.
• LACNIC (2.3.2.18): No special provision for leasing. A block transferred cannot be retransferred for a period of one year; the source party is ineligible for further allocations for a period of one year, and the recipient of a transfer must justify the address needs.
• RIPE (5.5): Re-allocations can be either on a permanent or non-permanent (i.e. lease) basis.

It is our understanding that even in regions where leasing is not regulated in the policies, leasing would be possible by means of a mutual contract.

Transfer of addresses across regions is currently not supported by the policies, and goes against the intentions of the RIR system. However, the historical process of address allocations is considered as unfair by many. Therefore, users are currently requesting that the policies are being changed in order to allow address transfer across regions.

An unregulated aspect of the policies is management of addresses that predate the RIR system (i.e. have been allocated before 1997). Formally, many of the resource holders are not in a contractual relationship with their region's RIR, which often is interpreted as allowing them to transfer addresses freely.

In addition, resource holders may chose to delegate their allocation to some service provider in some other region. It is not clear at this point what, if any, sanctions the RIRs would perform should they find out about such a delegation. This platform does not prevent such deals from being made; sellers and buyers should be aware that such a deal may be in a gray zone.