The Jargon File by Eric S. Raymond (sites to read books for free .TXT) 📖

Hacker Folklore

This appendix contains several legends and fables that illuminate the

meaning of various entries in the lexicon.

[15179]The Meaning of Hack: ...and three famous ones

[15180]TV Typewriters: A Tale of Hackish Ingenuity

[15181]A Story About Magic: By Guy Steele

[15182]Some AI Koans: Wit and Wisdom of the Masters

[15183]OS and JEDGAR: Intrigue and mayhem under ITS

[15184]The Story of Mel: One of hackerdom's great myths

Node:The Meaning of Hack, Next:[15185]TV Typewriters,

Previous:[15186]Appendix A, Up:[15187]Appendix A

The Meaning of `Hack'

"The word [15188]hack doesn't really have 69 different meanings",

according to MIT hacker Phil Agre. "In fact, [15189]hack has only one

meaning, an extremely subtle and profound one which defies

articulation. Which connotation is implied by a given use of the word

depends in similarly profound ways on the context. Similar remarks

apply to a couple of other hacker words, most notably [15190]random."

Hacking might be characterized as `an appropriate application of

ingenuity'. Whether the result is a quick-and-dirty patchwork job or a

carefully crafted work of art, you have to admire the cleverness that

went into it.

An important secondary meaning of [15191]hack is `a creative practical

joke'. This kind of hack is easier to explain to non-hackers than the

programming kind. Of course, some hacks have both natures; see the

lexicon entries for [15192]pseudo and [15193]kgbvax. But here are some

examples of pure practical jokes that illustrate the hacking spirit:

In 1961, students from Caltech (California Institute of Technology,

in Pasadena) hacked the Rose Bowl football game. One student posed

as a reporter and `interviewed' the director of the University of

Washington card stunts (such stunts involve people in the stands

who hold up colored cards to make pictures). The reporter learned

exactly how the stunts were operated, and also that the director

would be out to dinner later.

While the director was eating, the students (who called themselves

the `Fiendish Fourteen') picked a lock and stole a blank direction

sheet for the card stunts. They then had a printer run off 2300

copies of the blank. The next day they picked the lock again and

stole the master plans for the stunts -- large sheets of graph

paper colored in with the stunt pictures. Using these as a guide,

they made new instructions for three of the stunts on the

duplicated blanks. Finally, they broke in once more, replacing the

stolen master plans and substituting the stack of diddled

instruction sheets for the original set.

The result was that three of the pictures were totally different.

Instead of `WASHINGTON', the word ``CALTECH' was flashed. Another

stunt showed the word `HUSKIES', the Washington nickname, but

spelled it backwards. And what was supposed to have been a picture

of a husky instead showed a beaver. (Both Caltech and MIT use the

beaver -- nature's engineer -- as a mascot.)

After the game, the Washington faculty athletic representative

said: "Some thought it ingenious; others were indignant." The

Washington student body president remarked: "No hard feelings, but

at the time it was unbelievable. We were amazed."

This is now considered a classic hack, particularly because revising

the direction sheets constituted a form of programming.

Here is another classic hack:

On November 20, 1982, MIT hacked the Harvard-Yale football game.

Just after Harvard's second touchdown against Yale, in the first

quarter, a small black ball popped up out of the ground at the

40-yard line, and grew bigger, and bigger, and bigger. The letters

`MIT' appeared all over the ball. As the players and officials

stood around gawking, the ball grew to six feet in diameter and

then burst with a bang and a cloud of white smoke.

The "Boston Globe" later reported: "If you want to know the truth,

MIT won The Game."

The prank had taken weeks of careful planning by members of MIT's

Delta Kappa Epsilon fraternity. The device consisted of a weather

balloon, a hydraulic ram powered by Freon gas to lift it out of the

ground, and a vacuum-cleaner motor to inflate it. They made eight

separate expeditions to Harvard Stadium between 1 and 5 A.M.,

locating an unused 110-volt circuit in the stadium and running

buried wires from the stadium circuit to the 40-yard line, where

they buried the balloon device. When the time came to activate the

device, two fraternity members had merely to flip a circuit breaker

and push a plug into an outlet.

This stunt had all the earmarks of a perfect hack: surprise,

publicity, the ingenious use of technology, safety, and

harmlessness. The use of manual control allowed the prank to be

timed so as not to disrupt the game (it was set off between plays,

so the outcome of the game would not be unduly affected). The

perpetrators had even thoughtfully attached a note to the balloon

explaining that the device was not dangerous and contained no

explosives.

Harvard president Derek Bok commented: "They have an awful lot of

clever people down there at MIT, and they did it again." President

Paul E. Gray of MIT said: "There is absolutely no truth to the

rumor that I had anything to do with it, but I wish there were."

The hacks above are verifiable history; they can be proved to have

happened. Many other classic-hack stories from MIT and elsewhere,

though retold as history, have the characteristics of what Jan

Brunvand has called `urban folklore' (see [15194]FOAF). Perhaps the

best known of these is the legend of the infamous trolley-car hack, an

alleged incident in which engineering students are said to have welded

a trolley car to its tracks with thermite. Numerous versions of this

have been recorded from the 1940s to the present, most set at MIT but

at least one very detailed version set at CMU.

Brian Leibowitz has researched MIT hacks both real and mythical

extensively; the interested reader is referred to his delightful

pictorial compendium "The Journal of the Institute for Hacks,

Tomfoolery, and Pranks" (MIT Museum, 1990; ISBN 0-917027-03-5). The

Institute has a World Wide Web page at

[15195]http://hacks.mit.edu/Hacks/Gallery.html. There is rumored to be

a sequel entitled "Is This The Way To Baker Street?". The Caltech

Alumni Association has published two similar books titled "Legends of

Caltech" and "More Legends of Caltech".

Finally, here is a story about one of the classic computer hacks.

Back in the mid-1970s, several of the system support staff at

Motorola discovered a relatively simple way to crack system

security on the Xerox CP-V timesharing system. Through a simple

programming strategy, it was possible for a user program to trick

the system into running a portion of the program in `master mode'

(supervisor state), in which memory protection does not apply. The

program could then poke a large value into its `privilege level'

byte (normally write-protected) and could then proceed to bypass

all levels of security within the file-management system, patch the

system monitor, and do numerous other interesting things. In short,

the barn door was wide open.

Motorola quite properly reported this problem to Xerox via an

official `level 1 SIDR' (a bug report with an intended urgency of

`needs to be fixed yesterday'). Because the text of each SIDR was

entered into a database that could be viewed by quite a number of

people, Motorola followed the approved procedure: they simply

reported the problem as `Security SIDR', and attached all of the

necessary documentation, ways-to-reproduce, etc.

The CP-V people at Xerox sat on their thumbs; they either didn't

realize the severity of the problem, or didn't assign the necessary

operating-system-staff resources to develop and distribute an

official patch.

Months passed. The Motorola guys pestered their Xerox field-support

rep, to no avail. Finally they decided to take direct action, to

demonstrate to Xerox management just how easily the system could be

cracked and just how thoroughly the security safeguards could be

subverted.

They dug around in the operating-system listings and devised a

thoroughly devilish set of patches. These patches were then

incorporated into a pair of programs called Robin Hood' andFriar

Tuck'. Robin Hood and Friar Tuck were designed to run as `ghost

jobs' (daemons, in Unix terminology); they would use the existing

loophole to subvert system security, install the necessary patches,

and then keep an eye on one another's statuses in order to keep the

system operator (in effect, the superuser) from aborting them.

One fine day, the system operator on the main CP-V software

development system in El Segundo was surprised by a number of

unusual phenomena. These included the following:

Tape drives would rewind and dismount their tapes in the middle of

a job.

Disk drives would seek back and forth so rapidly that they would

attempt to walk across the floor (see [15196]walking drives).

The card-punch output device would occasionally start up of itself

and punch a [15197]lace card. These would usually jam in the

punch.

The console would print snide and insulting messages from Robin

Hood to Friar Tuck, or vice versa.

The Xerox card reader had two output stackers; it could be

instructed to stack into A, stack into B, or stack into A (unless

a card was unreadable, in which case the bad card was placed into

stacker B). One of the patches installed by the ghosts added some

code to the card-reader driver... after reading a card, it would

flip over to the opposite stacker. As a result, card decks would

divide themselves in half when they were read, leaving the

operator to recollate them manually.

Naturally, the operator called in the operating-system developers.

They found the bandit ghost jobs running, and [15198]gunned them...

and were once again surprised. When Robin Hood was gunned, the

following sequence of events took place:

!X id1

id1: Friar Tuck... I am under attack! Pray save me!

id1: Off (aborted)

id2: Fear not, friend Robin! I shall rout the Sheriff

of Nottingham's men!

id1: Thank you, my good fellow!

Each ghost-job would detect the fact that the other had been

killed, and would start a new copy of the recently slain program

within a few milliseconds. The only way to kill both ghosts was to

kill them simultaneously (very difficult) or to deliberately crash

the system.

Finally, the system programmers did the latter -- only to find that

the bandits appeared once again when the system rebooted! It turned

out that these two programs had patched the boot-time OS image (the

kernel file, in Unix terms) and had added themselves to the list of

programs that were to be started at boot time (this is similar to

the way MS-DOS viruses propagate).

The Robin Hood and Friar Tuck ghosts were finally eradicated when

the system staff rebooted the system from a clean boot-tape and

reinstalled the monitor. Not long thereafter, Xerox released a

patch for this problem.

It is alleged that Xerox filed a complaint with Motorola's

management about the merry-prankster actions of the two employees

in question. It is not recorded that any serious disciplinary

action was taken against either of them.

Node:TV Typewriters, Next:[15199]A Story About Magic,

Previous:[15200]The Meaning of Hack, Up:[15201]Appendix A

TV Typewriters A Tale of Hackish Ingenuity

Here is a true story about a glass tty: One day an MIT hacker was in a

motorcycle accident and broke his leg. He had to stay in the hospital

quite a while, and got restless because he couldn't [15202]hack. Two

of his friends therefore took a terminal and a modem for it to the

hospital, so that he could use the computer by telephone from his

hospital bed.

Now this happened some years before the spread of home computers, and

computer terminals were not a familiar sight to the average person.

When the two friends got to the hospital, a guard stopped them and

asked what they were carrying. They explained that they wanted to take

a computer terminal to their friend who was a patient.

The guard got