Deep Dive into NTP Pool's Popularity and Mapping

Proc. ACM Meas. Anal. Comput. Syst. Pub Date : 2024-02-16 DOI:10.1145/3639041

G. Moura, Marco Davids, C. Schutijser, Cristian Hesselman, John Heidemann, Georgios Smaragdakis

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Abstract

Time synchronization is of paramount importance on the Internet, with the Network Time Protocol (NTP) serving as the primary synchronization protocol. The NTP Pool, a volunteer-driven initiative launched two decades ago, facilitates connections between clients and NTP servers. Our analysis of root DNS queries reveals that the NTP Pool has consistently been the most popular time service. We further investigate the DNS component (GeoDNS) of the NTP Pool, which is responsible for mapping clients to servers. Our findings indicate that the current algorithm is heavily skewed, leading to the emergence of time monopolies for entire countries. For instance, clients in the US are served by 551 NTP servers, while clients in Cameroon and Nigeria are served by only one and two servers, respectively, out of the 4k+ servers available in the NTP Pool. We examine the underlying assumption behind GeoDNS for these mappings and discover that time servers located far away can still provide accurate clock time information to clients. We have shared our findings with the NTP Pool operators, who acknowledge them and plan to revise their algorithm to enhance security.

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深入了解 NTP 池的普及和映射

时间同步在互联网上至关重要，网络时间协议（NTP）是主要的同步协议。NTP Pool 是二十年前由志愿者发起的一项倡议，旨在促进客户端与 NTP 服务器之间的连接。我们对根 DNS 查询的分析表明，NTP 池一直是最受欢迎的时间服务。我们进一步调查了 NTP 池的 DNS 组件（GeoDNS），该组件负责将客户端映射到服务器。我们的研究结果表明，当前的算法存在严重偏差，导致整个国家出现时间垄断。例如，美国的客户由 551 台 NTP 服务器提供服务，而喀麦隆和尼日利亚的客户则分别由 NTP 池中 4k 多台服务器中的一台和两台服务器提供服务。我们研究了这些映射的 GeoDNS 背后的基本假设，发现位于遥远地方的时间服务器仍能为客户端提供准确的时钟时间信息。我们已与 NTP Pool 运营商分享了我们的发现，他们对此表示认可，并计划修改算法以提高安全性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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Proc. ACM Meas. Anal. Comput. Syst.

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