An ARP Based Approach for Port Scavenging and IPv4 Address Sharing

The Internet is rapidly nearing IPv4 address space exhaustion. Current projections predict that within the next two years, all IPv4 address blocks will have been assigned. IPv6 adoption on the other hand has not ramped up as rapidly. As we transition from an Internet built on an abundance of IP addresses to one of scarcity, innovative techniques that allow us to do more with less are likely to flourish. One such class of emerging techniques attempts to utilize unused port ranges to implement IP address sharing. We call this class of approaches Port Scavenging. In this paper we present a unique approach that allows multiple end hosts on a network to share a single IPv4 address by relying on a modified hardware address resolution protocol. Using the proposed approach it is possible to allow thousands of end hosts to share a single IPv4 address and at the same time be able to maintain an end-to-end consistent network. Our approach is fundamentally different other techniques, as it does not require that packets from the end-host be modified at the network layer by an intermediate entity as they transit the network. In addition, each end-host can use a valid routable public IP address. We have developed an initial implementation of our ideas via a modified Linux kernel which demonstrates the feasibility of our approach.