Internet privacy is increasingly important on the modern Internet. Users are looking to control the trail of data that they leave behind on the systems that they interact with. Multi-Party Relay (MPR) architectures lower the traditional barriers to adoption of privacy enhancing technologies on the Internet. MPRs are unique from legacy architectures in that they are able to offer privacy guarantees without paying significant performance penalties. Apple's iCloud Private Relay is a recently deployed MPR service, creating the potential for widespread consumer adoption of the architecture. However, many current Internet-scale systems are designed based on assumptions that may no longer hold for users of privacy enhancing systems like Private Relay. There are inherent tensions between systems that rely on data about users -- estimated location of a user based on their IP address, for example -- and the trend towards a more private Internet. This work studies a core function that is widely used to control network and application behavior, IP geolocation, in the context of iCloud Private Relay usage. We study the location accuracy of popular IP geolocation services compared against the published location dataset that Apple publicly releases to explicitly aid in geolocating PR users. We characterize geolocation service performance across a number of dimensions, including different countries, IP version, infrastructure provider, and time. Our findings lead us to conclude that existing approaches to IP geolocation (e.g., frequently updated databases) perform inadequately for users of the MPR architecture. For example, we find median location errors >1,000 miles in some countries for IPv4 addresses using IP2Location. Our findings lead us to conclude that new, privacy-focused, techniques for inferring user location may be required as privacy becomes a default user expectation on the Internet.

翻译：互联网隐私在现代互联网中日益重要。用户希望控制他们在所交互系统上留下的数据痕迹。多方中继（MPR）架构降低了采用互联网隐私增强技术的传统门槛。MPR与旧架构的不同之处在于，它们能够在无需显著性能损失的情况下提供隐私保障。苹果的iCloud Private Relay是一项最近部署的MPR服务，有望促进消费者对该架构的广泛采用。然而，当前许多互联网规模的系统基于的假设可能不再适用于使用诸如Private Relay等隐私增强系统的用户。依赖于用户数据（例如，基于IP地址估算用户位置）的系统与互联网向更隐私方向发展的趋势之间存在固有矛盾。本研究在iCloud Private Relay使用的背景下，考察了一项广泛用于控制网络和应用行为的核心功能——IP地理位置定位。我们研究了主流IP地理位置定位服务在位置准确性方面的表现，并将其与苹果公开发布、明确用于辅助定位Private Relay用户的位置数据集进行比较。我们针对多个维度（包括不同国家、IP版本、基础设施提供商及时间）刻画了地理位置定位服务的性能。研究发现表明，现有IP地理位置方法（例如频繁更新的数据库）对MPR架构的用户表现不佳。以IP2Location为例，我们发现某些国家对IPv4地址的中位定位误差超过1000英里。我们的结论是，随着隐私成为互联网用户的默认预期，可能需要开发新的、以隐私为中心的推断用户位置的技术。