This paper is focused on privacy issues related to the prefix part of IPv6 addresses. Long-lived prefixes may introduce additional tracking opportunities for communication partners and third parties. We outline a number of prefix alteration schemes that may be deployed to maintain the unlinkability of users' activities. While none of the schemes will solve all privacy problems on the Internet on their own, we argue that the development of practical prefix alteration techniques constitutes a worthwile avenue to pursue: They would allow Internet Service Providers to increase the attainable privacy level well above the status quo in today's IPv4 networks.
Lindqvist and Tapio @cite_6 propose to implement a technique in the operating system of networked clients. Instead of only changing IP addresses, their solution takes into account that identifiers on other layers of the network stack can also be used to track users (e. ,g., MAC addresses and port numbers). The design requires a locally installed translation daemon that replaces all identifiers on all layers at once for every new outbound flow of the client, which ensures that consecutive as well as concurrent activities remain unlinkable. A prototypical implementation of the system is shown to be compatible with several well-known Linux applications. As it solely operates on the client side, protocol stack virtualisation cannot influence the provider-controlled address prefixes, though.
@cite_6
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Previously proposed host-based privacy protection mechanisms use pseudorandom or disposable identifiers on some or all layers of the protocol stack. These approaches either require changes to all hosts participating in the communication or do not provide privacy for the whole protocol stack or the system. Building on previous work, we propose a relatively simple approach: protocol stack virtualization. The key idea is to provide isolation for traffic sent to the network. The granularity of the isolation can be, for example, flow or process based. With process based granularity, every application uses a distinct identifier space on all layers of the protocol stack. This approach does not need any infrastructure support from the network and requires only minor changes to the single host that implements the privacy protection mechanism. To show that no changes to typical applications are required, we implemented the protocol stack virtualization as a user space daemon and tested it with various legacy applications.