"That's the tapeworm!"
Weyer
said.
"The
what?"
"The tapeworm, from
The
Shockwave Rider.
I'll give you a copy."
The
Shockwave Rider
was a recent
novel by
the British science fiction
writer John Brunner. In the course of
the story
its hero unleashes an
invulnerable self-perpetuating virus—perhaps the first computer virus of
fact or fiction
—
to destroy a sinister global network.
("It can't be killed.
Not
short of demolishing the net!")
Paging through
Weyer's
copy of the
book, Shoch thought the similarities between his device and Brunner's
were mostly metaphorical. "It wasn't quite what we were doing, although
it did evoke the right images," he recalled. He appropriated the name
anyway, slightly truncated, and from that moment on Shoch's Ethernet-
polling program was known around the building as "the worm."
Rather than destroy the network like Brunner's hero, Shoch aimed to
enhance it by allowing PARC's distributed machines to perform computations in concert. Theoretically, the worm could be programmed to start
out in one machine and reach out to others as its computing needs
expanded. "In the middle of the night, such a program could mobilize
hundreds of machines in one building," he wrote later. Before morning,
as users arrived to reclaim their machines, the worm would retreat. After
hibernating in a machine or two during daylight, it would re-emerge the
next evening—an image that led one of Shoch's colleagues to liken it less
to a worm than to a vampire.
The point was to convert 200 Altos, each with the power of a single
processor, into one distributed, interlinked machine with the exponential
power of 200! Shoch's brainstorm hinted at a method of compounding
processor power that would one day find wide application in the field of
supercomputers. (The IBM machine "Deep Blue" employed a distantly
related architecture when it instantaneously mustered billions of calculations to defeat chess grandmaster Gary Kasparov in 1997.)
Shoch was well aware that the privilege of taking over scores of idle
computers in their owners' absence meant he would have to govern his
program stringently. He invested his worm with the ability to seek out
idle Altos, boot up a host machine through the network, and replicate
itself by sending copies of itself from machine to machine. But he
strictly forbade it access any Alto's disk drive—a necessary precaution
lest it inadvertently overwrite someone's work, which he knew would
be viewed as "a profoundly antisocial act."
Even within those limits he reveled in finding new ways to extend and
elaborate the worm. In time he improved the program to the point where
it could remain in constant communication with its dispersed offspring, so
it would know how many segments were out and what they were doing.
The mother worm could even sense if an Alto had crashed with an active
segment inside, a signal that she would need to colonize another host.
But
in imagining a world with
a
tapeworm gone amok,
John Brunner
had
not underestimated the
obstinacy
of a runaway program. Eventually the moment arrived for
Shoch
and his colleagues
to
discover just
how stubborn and dangerous
one
could
be.
The worm was about to
commit an "antisocial" act beyond anything
they
could have foreseen.
One
night they set a small
worm loose to test
a control function.
Confi
dent they had loaded a perfectly
innocuous
program into
a
modest number of Altos, they left it running
and went home. At
some point
—they
never
figured out exactly
when and why
—
one
piece of the program
became corrupted so badly
that it crashed its host
computer. Sensing it
had
lost a segment, the control worm
sent out
a tendril to another idle
Alto. That
host crashed, and
the
next,
and the
next. The program was
now
probing insatiably for
new hosts and "killing"
every one it touched.
For
hours the silent carnage
spread through the
building until scores of
machines were disabled. Then
morning came.
Ted
Kaehler was one of those
who
got
to Iris
office to find his machine
in a
state of catatonia. Without
thinking twice,
he rebooted.
But
it soon
seemed that the entire building
had been taken
over by a malevolent
spirit. Whenever a machine
went
idle,
instead
of slipping routinely into
the memory diagnostic it would suffer
this bizarre
seizure and the.
"We
couldn't
get rid of it," he recalled.
Finally
the alarm reached
the worm researchers. It was
still
early
in
the
morning when Boggs and
Shoch responded,
barely able
to
wipe
the sleep from their eyes.
They began disassembling
the
network
and
probing its recesses, like
exterminators pursuing
rats through
a
sewer
line. Even after they were sure
they
had eradicated the program from
every Alto,
machines continued to crash bizarrely. Exhausted from the
ordeal, Shoch found himself reimagining
scenes
from
The
Shockwave
Rider
—"workers running
around the building,
fruitlessly
trying
to
chase
the worm and stop it before
it moves
somewhere else."
The
building had to be harboring a
reservoir
of diseased worms still
seeking hosts. Finally they realized where the nest
was
located.
More
than a dozen Altos were up on the third floor, the administrative quarters.
No
one up there had arrived for work yet, and the offices were all locked.
That left them no choice but
to
unleash their neutron bomb. Thanks to
a lucky precognition, Shoch had equipped the worm with a self-destruct
mechanism, like a spymaster providing his agent with a suicide capsule as
insurance against some unpredictable disaster. He injected a specially
coded packet into the Ethernet that instructed every worm to instantly
stop whatever it was doing. For a few nerve-racking seconds he waited.
Then he checked the system.
To his relief, all the worm activity had ceased. That was the good news.
The bad news was that the entire Ethernet had been figuratively reduced
to a smoking ruin. Scattered around the building were 100 dead Altos.
"The embarrassing results," he said, "were left for all to see."
With that lone exception, the worm ranked as a welcome addition to
the PARC programming arsenal. Shoch came to calling the plain-vanilla
version the "existential" worm—it simply reached out for hosts, copied
itself, and self-destructed after a programmed interval. But there were
dozens of other applications. The Billboard worm, for example, snaked
through the system depositing on every machine a bitmapped image,
such as a "cartoon of the day" to greet workers in the morning. The Alarm
Clock worm maintained a table of wakeup calls, and at the pertinent time
accessed PARC's telephone directory and placed a call to the user's
phone. The Peeker logged the results of each night's memory tests and
notified PARC technicians which machines might need a new chip.
Shoch always thought of these applications as "toy programs." In his
view the worm's real value lay in tying widely distributed computers into
multi-machine units of exceptional power. Yet the potential of parallel
computing would not become evident to the outside world for a long
time. Silicon microprocessors would soon become powerful enough to
handle complex calculations without help. Only years later would scientists again need to harness the power of multiple processors at once,
when massively parallel processing would become an integral part of
supercomputing.
Years later, too, the genealogy of Shoch’s worm would come full circle.
Soon after he published a paper about the worm citing
The Shockwave
Rider,
he received a letter from John Brunner himself. It seemed that
most science fiction writers harbored an unspoken ambition to write a
book
that actually predicted
the
future.
Their
model was
Arthur C.
Clarke, the prolific author of
2001:
A Space Odyssey,
who had become
world-famous for forecasting
the
invention
of
the geosynchronous communications satellite in an earlier short
story.