Australian researchers have begun collating information from networks across the world in an attempt to figure out how many usable blocks of Internet Protocol version 4 (IPv4) addresses remain unused.
Associate Professor Lachlan Andrew, one of the project researchers at the Swinburne University in Melbourne, said the aim of the STING project (short for "Surveying the INternet's Growth") was to calculate the saturation of rapidly depleting IPv4 address stock, and the ability to recognise IPv6.
Andrew said the study had already verified a couple of hundred million IP addresses that were currently not used — but could be reallocated — simply by pinging the machines and registering a response.
Regional internet registry APNIC (Asia Pacific Network Information Centre) also has placed code on web pages to assist with detecting any IPv4 addresses behind firewalls or in use by devices such as IP telephones.
"Almost all of the available IPv4 address space has been allocated but a huge fraction of it has been allocated to people who are not using it or are using only a small part of it," Andrew said.
"Our goal is to find out what's actually being used."
The researchers plan to borrow techniques from ecology, taking another sample at a later date and comparing the data, and emulating the "capture-recapture" method that ecologists use to estimate animal populations.
The STING research team called on Australian network operators late last month to provide information on how organisations allocated their IP addresses.
Andrew said the researchers did not want access to sensitive or private user information, just advice on the ISP or corporation's general strategies — such as when they use static versus dynamic IP addresses, how often the IP addresses changed at the client end, and whether the addresses are allocated in sequential order.
The study is global in scope but Andrew said it was likely that Australian network operators took a similar approach to IP allocation as their counterparts overseas.
He said it was too early to announce any preliminary findings but the team expected to find a large amount of excess IPv4 capacity, especially in the US and other countries that connected to the internet early.
"In the long run we're expecting that a lot of space in contiguous blocks could be sold," he said.
"[In the early days] you had companies like IBM and Hewlett Packard being given huge allocations like 16 million addresses in one chunk and it's only likely they're using part of such a huge block."
Although it was legally debatable whether IP addresses were a company asset or owned by ICANN, Andrew said some companies had begun offering their unused stocks at negotiated prices.
Nortel reportedly sold about 666,624 unused IPv4 addresses to Microsoft for $7.5 million last year, as part of the former company's Chapter 11 bankruptcy.
Others have established IPv4 'grey' trading markets for unused address stocks.
Andrew said even if a large amount of IPv4 space was freed up, it would still be necessary to move to IPv6.
"Unless the economy stops growing, the number of IP addresses will continue to increase so it's a matter of 'when' rather than 'if'," he said.
He added that incumbent ISPs with plenty of IPv4 addresses had market power because of the overall scarcity of addresses and therefore little incentive to lead the migration to IPv6.
"Very little content is available on IPv6 and very few users [can access it] so if you just gave content providers an IPv6 address without having IPv4, they're not going to have much custom, he said.
"There's this huge inertia to get content and users migrating to IPv6."