The thorny problem of preserving internet time

In 1977, David Mills, an eccentric engineer and computer scientist, took a job at comsatD.C. Mills, a Washington-based satellite company, was a well-established reformer: He once built an audio device for his girlfriend’s uncle, and he had consulted Ford about how to put paper-tape computers in cars. now in comsatMills became involved in ARPANET, the computer network that would become the precursor to the Internet. Few researchers were actually using the network to connect remote computers and business information. But the accuracy of that exchanged data was compromised by an apparent deficiency: the machines did not share a single reliable synchronous time.

Over the decades, Mills has gained extensive experience in mathematics, engineering, and computer science. In the early 1970s, as a lecturer at the University of Edinburgh, he wrote programs that decode short-wave radio and telegraph signals. Later, largely for fun, he studied how clocks in the power grid could wander several seconds during a hot summer’s day. (The extent of their shifts depended not only on temperature, but on whether the grid was using coal or hydropower.) Now focus on the problem of keeping time over a remote computer network. Mills learned that the clock’s time is the result of a never-ending search for consensus. Even the times listed by the world’s most accurate government-held “master clocks” are combinations of the readings of many atomic clocks. The master clocks, in turn, are averaged to help establish international civil time, known as Coordinated Universal Time and initialized as UTC

To solve the problem of time synchronization on ARPANETMills built what programmers call a protocol – a set of rules and procedures that create a common language for disparate devices. The ARPANET It was experimental and volatile: electronics failed regularly, and technological misconduct was common. His protocol sought to discover and correct those misdeeds, creating consensus about time through an ingenious system of skepticism. Mills prided itself on rude labels, and so its clock sync system distinguishes trusted “truth hunters” from misleading “fake labels.” An operating system called Fuzzball, which he designed, facilitated early work. Mills called its creation the Network Time Protocol, and NTP soon became a major component of the nascent Internet. The programmers followed his instructions when they wrote the timekeeping code for their computers. By 1988, Mills had refined NTP to the point that he could synchronize the clocks of connected computers telling us dramatically different times within tens of milliseconds—a fraction of the blink of an eye. “I always thought this was some kind of black magic,” Vint Cerf, an Internet infrastructure pioneer, told me.

Today, we take universal time synchronization for granted. It is critical to the Internet, and thus to civilization. Vital systems—power grids, financial markets, and communications networks—depend on them to keep records and sort cause from effect. NTP works in partnership with satellite systems, such as the Global Positioning System (GPS), and other technologies to synchronize time on many of our online devices. For example, time kept by accurate and closely coherent atomic clocks, can be broadcast via GPS to many receivers, including those in cell towers; These receivers can be attached to NTP servers that then distribute time across devices linked together by the Internet, nearly all of which run NTP (atomic clocks can also feed time directly to NTP servers.) The protocol runs on billions of devices, in coordination. time on every continent. Society has never been more synchronized.

For decades, Mills was the one who decided how NTP should operate (although he disputes the suggestion that he acted with complete sovereignty). Quirky, prickly, reliable, and sometimes mysterious — “He does not suffer fools with pleasure,” said one old collaborator — he was like a daddy on the Internet. But his term is coming to an end. Mills was born with glaucoma. As a child, the surgeon was able to save some vision in his left eye, and he always worked with very large computer screens. About a decade ago, his eyesight began to fail, and he is now completely blind. Checking computer code and writing explanations and corrections became very boring. It is almost impossible to draw diagrams or form complex mathematical equations.

Two years ago, I visited Mills at his humble home in suburban Delaware. He and his wife, Beverly, have lived there since 1986, when Mills became a professor at the University of Delaware, a position he held for twenty-two years until his retirement. As we sat in his kitchen, our conversation was regularly interrupted by a robotic voice announcing the time from the next room. The oven and microwave clocks were out of sync. Mills, who has a white beard and wears a charcoal fisherman’s jacket, keeps track of time himself using a speaking wristwatch, which communicates radio signals with a master clock in Colorado.

He led me to his upstairs office, slowly making his way through the house feeling a series of memorized “navigation points”. In his office, with a cat lying on top of some ham radios, Mills sat in front of his computer. He used the keyboard to pull up a research paper he was working on, with suggestions for improving NTP (he asked his wife and daughter to proofread what he was writing). As he was using the arrow keys to scroll, the computer spoke loudly. “This note explores new security and protocol improvements,” said one of the voices. “Empty. Table of contents. Blank. One. Two. Two points. . . . Three. Three. Four. Four one point. . . .” was quickly lost. “I do what I can with the sound you hear,” Mills said. “But I note myself and comment on the following: Man is made to compose in English with the help of the eyeball.”

Technology does not stand still. The Internet continues to grow in size and complexity; Even as its infrastructure advances, our world is increasingly dependent on its work. The continuous development of an online time synchronization system is essential. However, Mills’ inability to contribute quickly to NTP drained his power over him. In his absence, it seems that only a few people are able and willing to oversee crucial programs that have been overlooked. A competition has begun to influence how online clocks are kept in sync.

Mills was born in 1938 in Oakland, California, eleven years after developing the first quartz watch and nine years before building the first transistor. He took a steam-powered train to a school for the visually impaired in San Mateo, and admired the engineers who run it. In his teens, he became a railroad model and ham radio, communicating with friends and fixing Antarctic Navy bees through their wives. His father, an engineer and salesman, co-founded National Oil Seal, a company that manufactures equipment for sealing inside machines. (“You might not know what it is, but there are at least two in your engine,” his father told him of the SEALs.) His mother trained as a pianist at the Toronto Conservatory of Music before staying home to raise him and his two younger brothers.

The family moved, and Mills’ teachers did not always understand his visual impairment. Mills remembers an eleventh-grade teacher telling him, “You’ll never go to college”—a remark that was “like waving a flag in front of a bull.” In 1971, Mills received his Ph.D. in Computer and Communication Sciences at the University of Michigan; After lecturing for two years in Edinburgh, he moved with his wife and two children to the University of Maryland, which deprived him of the position five years later. “It was the best thing that ever happened to me,” Mills said. Work started in comsatwhere he had access to funding from the Department of Defense, part of which was earmarked for ARPANET. “It was a sandbox,” he later told an interviewer. “We were just told, ‘Do good.’ But the good deeds were things like developing email and protocols.” He told me that part of the allure of the time sync business was that he was the only one doing it. He had his “little fief”.

At NTP, Mills built a system that allowed endless fixes, and found it fun to improve. He noted that “the actual use of time information was not of central importance.” The nascent internet had just a few hours to sync. But during the 1980s, the network grew rapidly, and by the 1990s, the widespread adoption of personal computers from the Internet required the integration of millions more devices than its early designers had envisioned. Programmers created NTP versions that worked on Unix and Windows machines. Others wrote “reference implementations” of NTP – open source code rules that explain how the protocol works, which were freely available for users to adapt to. government agencies, including the National Institute of Standards and Technology (Nest) and the US Naval Observatory, distribute the time held by their master clocks using NTP

A loose community of people all over the world have set up their own servers to save time through the protocol. In the year 2000, NTP servers made eighteen billion time synchronization requests from several million computers—and in the next few years, with the spread of broadband, requests to the busiest NTP servers increased tenfold. Mills wrote in a 2003 article that time servers were once “well-lit in the United States and Europe but dark elsewhere in South America, Africa, and the Pacific”. “Today, the sun never sets or comes close to the horizon on NTP.” Programmers began to treat the protocol as an assumption – it seemed natural to them that synchronous time was readily available and reliable. Little Mills fiefdom was everywhere.

NTP works by telling computers to send small, time-stamped messages to time-checkers that are superior to them in a hierarchy. The upper layer of the hierarchy consists of servers closely linked to high-precision clocks that are kept in tight synchronization with Coordinated Universal Time. Then time flows, from layers to layers, to devices at the bottom of the hierarchy, like regular laptops. The protocol tracks the moments that elapse when a time-checking message is sent, received, returned, and received again by its original sender. All the while, an array of algorithms — a “popcorn spike blocker,” a “huff-n’-puff filter” — scroll through the data, sorting out liars and truth hunters and instructing clocks on how to set their times based on what time-stamped messages tell them.

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