“The word hack doesn’t really have 69 different meanings”, according to MIT hacker Phil Agre. “In fact, 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 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 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 pseudo and 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.
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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 AM, 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.”
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’ and ‘Friar 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.
Finally, here is a wonderful hack story for the new millennium:
1990’s addition to the hallowed tradition of April Fool RFCs was RFC 1149, A Standard for the Transmission of IP Datagrams on Avian Carriers. This sketched a method for transmitting IP packets via carrier pigeons.
Eleven years later, on 28 April 2001, the Bergen Linux User’s Group successfully demonstrated CPIP (Carrier Pigeon IP) between two Linux machines running on opposite sides of a small mountain in Bergen, Norway. Their network stack used printers to hex-dump packets onto paper, pigeons to transport the paper, and OCR software to read the dumps at the other end and feed them to the receiving machine’s network layer.
While all acknowledged the magnitude of this achievement, some debate ensued over whether BLUG’s implementation was properly conformant to the RFC. It seems they had not used the duct tape specified in 1149 to attach messages to pigeon legs, but instead employed other methods less objectionable to the pigeons. The debate was properly resolved when it was pointed out that the duct-tape specification was not prefixed by a MUST, and was thus a recommendation rather than a requirement.
The perpetrators finished their preliminary writeup in this wise: “Now, we’re waiting for someone to write other implementations, so that we can do interoperability tests, and maybe we finally can get the RFC into the standards track… ”.