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The First Message Transmission

NOTE: Fifty years ago, two things happened that changed the world. First a human being set foot on the moon, then three months later a simple message between two computers marked an important step in the development of the Internet. In this special guest blog, Dr. Leonard Kleinrock of UCLA, a legendary Internet pioneer, tells the behind the scenes story of what happened leading up to that special day in the development of one of the greatest communication tools humankind has ever developed.

Many realize that 50 years ago, on October 29, 1969, the first message was successfully sent over the ARPANET, which eventually evolved into the Internet. But few know the story that led up to that message.

On June 3, 1968, the ARPANET Program Plan was formally submitted to the U.S. Defense Department’s Advanced Research Project Agency (ARPA) by Larry Roberts. It was approved on June 21, 1968, and that meant the ARPANET process was now officially underway.

By the end of July 1968, a Request for Quotation (RFQ) for the network Interface Message Processors (IMPs) was mailed to 140 potential bidders.

The RFQ resulted in 12 proposals being submitted. As these proposals were being evaluated at ARPA, Roberts awarded a research contract to me at UCLA in October to create the Network Measurement Center (NMC).

The task of the NMC was to measure the behavior of the ARPANET by conducting experiments to determine its faults, performance, and outer limits through the use of stress tests.

I was fortunate to have a star team of graduate student researchers, developers, and staff for this project. A week before Christmas 1968, Bolt, Beranek and Newman (BBN) won the competitive bid and was awarded the contract to develop the IMP-to-IMP subnetwork.

The first four sites were selected due to their ability to provide specialized network services and/or support. They were:

  •  University of California Los Angeles (UCLA)
    • To provide the NMC under my supervision.
  • Stanford Research Institute (SRI)
    • To provide Doug Engelbart’s Human Intellect Augmentation System.
  • University of California Santa Barbara
    • To provide interactive graphics.
  • University of Utah
    • To provide advanced 3D graphics.

Things began to move rapidly at this point. The date of the first IMP delivery, scheduled to arrive to us at UCLA in early September 1969, was fast approaching.

Meanwhile, at the NMC, we were busy collecting data so that we could predict performance of the network based on my earlier 1962 theory. For this, it was necessary to estimate the traffic loads that the host sites would present to the network.

Roberts and I contacted a number of the early sites and asked them how much traffic they expected to generate and to which other sites. We also asked them how much traffic they would allow into their sites. To my surprise, many refused to allow any traffic from the network to use their hosts. Their argument was that their hosts were already fully utilized serving their local customer base. Eventually they relented and provided their expected traffic loads. That traffic matrix was used in the July 1968 RFQ and in a paper I published in June 1969, thereby sealing their commitment.

On July 3, 1969, two months before the IMP was due to arrive, UCLA put out a press release announcing the imminent deployment of the ARPANET.

In the release I described what the network would look like, and what would be a typical application. I am quoted in the final paragraph as making several predictions, “As of now, computer networks are still in their infancy, but as they grow up and become more sophisticated, we will probably see the spread of ‘computer utilities,’ which, like present electric and telephone utilities, will service individual homes and offices across the country.”

I’m gratified to see that the future proved my predictions to be accurate:

  • The “computer utilities” comment accurately anticipated the emergence of web-based IP services.
  • My “electric and telephone utilities” comment correctly anticipated the ability to plug in anywhere to an always on and “invisible” network.
  • The “individual homes and offices” comment anticipated ubiquitous access.

Notably, what I did not foresee was the powerful social networking side of the Internet and its rapidly growing impact on our society.

The First Message

The ARPANET’s first host-to-host message was sent at 10:30 p.m. on October 29, 1969 when one of my programmers, Charley Kline, proceeded to “login” to the SRI host from the UCLA host.

The procedure was to type in “log,” and the system at SRI was clever enough to fill out the rest of the command, adding “in,” thus creating the word “login.”

Charley at our end and Bill Duvall at the SRI end each had a telephone headset so they could communicate by voice as the message was being transmitted. Note the irony that here we were using the telephone network to launch the new technology of packet switching which would destroy the telephone network!

At the UCLA end, Charley typed in the “l” and asked SRI “did you get the l?” “Got the l” came the voice reply. He typed in the “o,” “Did you get the o?” and received “Got the o.” UCLA then typed in the “g,” asked “Did you get the g?” at which point the system crashed! This was quite a beginning.

So, the very first message on the Internet was the prescient word “lo” (as in, “lo and behold!”). We hadn’t prepared a special message (as did, for example, Samuel Morse with “What Hath God Wrought”) but our “lo” could not have been a more succinct, a more powerful or a more prophetic message. Heck, we didn’t have a camera or even a voice recorder. The only record of this event is an entry in our IMP log recording.

The ARPANET and its successor, the Internet, had now been launched.

Leonard Kleinrock joined two other Internet pioneers – Vint Cerf and Steve Crocker – to chat with the staff of ICANN org on 15 October 2019. They discussed that first message sent over the ARPANET and the early days of the Internet. You can watch a video at


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