>>"Siddharth" == Siddharth Kashyap <[EMAIL PROTECTED]> writes:
Siddharth> Can someone tell me what is a fork bomb?
The jargon file is your friend.
:fork bomb: /n./ [Unix] A particular species of {wabbit}
that can be written in one line of C (`main()
{for(;;)fork();}') or shell (`$0 & $0 &') on any Unix system,
or occasionally created by an egregious coding bug. A fork bomb
process `explodes' by recursively spawning copies of itself
(using the Unix system call `fork(2)'). Eventually it eats
all the process table entries and effectively wedges the system.
Fortunately, fork bombs are relatively easy to spot and kill, so
creating one deliberately seldom accomplishes more than to bring
the just wrath of the gods down upon the perpetrator. See also
{logic bomb}.
:logic bomb: /n./ Code surreptitiously inserted into an
application or OS that causes it to perform some destructive or
security-compromising activity whenever specified conditions are
met. Compare {back door}.
:back door: /n./ A hole in the security of a system
deliberately left in place by designers or maintainers. The
motivation for such holes is not always sinister; some operating
systems, for example, come out of the box with privileged accounts
intended for use by field service technicians or the vendor's
maintenance programmers. Syn. {trap door}; may also be called a
`wormhole'. See also {iron box}, {cracker}, {worm},
{logic bomb}.
Historically, back doors have often lurked in systems longer than
anyone expected or planned, and a few have become widely known.
Ken Thompson's 1983 Turing Award lecture to the ACM admitted the
existence of a back door in early Unix versions that may have
qualified as the most fiendishly clever security hack of all time.
In this scheme, the C compiler contained code that would recognize
when the `login' command was being recompiled and insert some
code recognizing a password chosen by Thompson, giving him entry to
the system whether or not an account had been created for him.
Normally such a back door could be removed by removing it from the
source code for the compiler and recompiling the compiler. But to
recompile the compiler, you have to *use* the compiler -- so
Thompson also arranged that the compiler would *recognize when
it was compiling a version of itself*, and insert into the
recompiled compiler the code to insert into the recompiled
`login' the code to allow Thompson entry -- and, of course, the
code to recognize itself and do the whole thing again the next time
around! And having done this once, he was then able to recompile
the compiler from the original sources; the hack perpetuated itself
invisibly, leaving the back door in place and active but with no
trace in the sources.
The talk that suggested this truly moby hack was published as
"Reflections on Trusting Trust", "Communications of the ACM
27", 8 (August 1984), pp. 761--763 (text available at
http://www.acm.org/classics). Ken Thompson has since
confirmed that this hack was implemented and that the Trojan Horse
code did appear in the login binary of a Unix Support group
machine. Ken says the crocked compiler was never distributed.
Your editor has heard two separate reports that suggest that the
crocked login did make it out of Bell Labs, notably to BBN, and
that it enabled at least one late-night login across the network by
someone using the login name `kt'.
--
For three years, the young attorney had been taking his brief
vacations at this country inn. The last time he'd finally managed an
affair with the innkeeper's daughter. Looking forward to an exciting
few days, he dragged his suitcase up the stairs of the inn, then
stopped short. There sat his lover with an infant on her lap!
"Helen, why didn't you write when you learned you were pregnant?" he
cried. "I would have rushed up here, we could have gotten married,
and the baby would have my name!" "Well," she said, "when my folks
found out about my condition, we sat up all night talkin' and talkin'
and finally decided it would be better to have a bastard in the
family than a lawyer."
Manoj Srivastava <[EMAIL PROTECTED]> <http://www.debian.org/%7Esrivasta/>
1024R/C7261095 print CB D9 F4 12 68 07 E4 05 CC 2D 27 12 1D F5 E8 6E
1024D/BF24424C print 4966 F272 D093 B493 410B 924B 21BA DABB BF24 424C
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