IPv4 stands for Internet Protocol version 4: a set of technical rules that define how computers communicate over the internet. It is the underlying technology that allows us to connect devices to the web. Whenever a device (PC, Mac, smart phone, etc.) accesses the internet, it is assigned a unique numerical IP address. In order to send data from one computer to another via the web, a data packet must be transferred that contains the IP address of both the sending and receiving devices. IP addresses are an essential part of the web infrastructure, as they are needed to communicate and send data. IPv4 was developed for ARPANET in 1978, and has been deployed since 1981.
IPv4 is based on a 32 bit dotted decimal notation, and provided 2^32 (about 4.2 billion) addresses. IANA (Internet Assigned Numbers Authority) is the entity in charge of allocating IP address space to RIRs (Regional Internet Registries) which in turn distribute the addresses to various corporations and institutes. It has been known for several years that the number of available IPv4 addresses was being depleted, and in fact the last allotment was distributed to RIRs on 2/3/2011.
IPv6 is the sixth revision to Internet Protocol and the successor to IPv4. It also provides a unique numerical IP address so internet enabled devices can function. However IPv6 is based on a 128 bit hexadecimal notation, and will provide 2^128 (approximately 340,282,366,920,938,463,463,374,607,431,768,211,456) IP addresses. While not infinite, this will be sufficient to provide internet addresses for all the PCs, Macs, smart phones and other internet devices for many years to come.
The difficulty with getting all entities to switch from IPv4 to IPv6 is that v6 is not backwards compatible to v4. IPv4 and IPv6 run as parallel networks, so exchanging data between protocols requires special gateways. In order to switch, all operating systems, software, routers and firewalls must be upgraded, and vendors’ IT and customer service staff require training. While most newer operating systems are IPv6 capable, a large percentage of individuals and businesses are still using operating systems and devices that are IPv4 capable only. As we continue into this transition period, more vendors will find that they need to support both IPv4 and IPv6.
An important solution for working with both protocols is dual stacking. A dual stacked device can work with both IPv4 and IPv6 devices and other dual stacked devices. DNS (Domain Name System) works with dual stacked devices – if given an IPv4 address the dual stack device will send an IPv4 packet, and if given an IPv6 address it will send an IPv6 packet. The drawback of dual stacking is that everything would need an IPv4 and an IPv6 address, and systems already on IPv6 only would not have an IPv4 address. NAT (Network Address Translation) allows a device such as a router to provide one IP address for use by a private network of computers and devices, thereby reducing the number of IPv4 addresses needed by modifying IP address information in IP packet headers while in transit. One drawback of NAT is that it was designed to give IETF time to work on the IP address depletion issue, so it is a temporary fix not designed with security or privacy in mind, making it a weak link for attacks. Also, some entities may rely on using NAT to avoid going to the time and expense of upgrading to IPv6, when they should be making that the priority.
References
Klein, Joe. “IPv6 Playground – Next Hope.” 23 July 2010. IPv6Sec. 21 July 2011
<https://sites.google.com/site/ipv6security/>.
IPv4 Depletion – IPv6 Implementation. 03 February 2011. 21 July 2011
< https://www.arin.net/knowledge/v4-v6.html>.
Doyle, Jeff. The Dual Stack Dilemma. 04 June 2009. 21 July 2011
Sojourn 