back door

rear door, back entrance, exit

In typical English usage, a back door is the door around the back of a building. Thus, "employees must enter the store via the back door." Several concepts are named after it:Backdoor (computing), is a hidden method for bypassing normal computer authentication systems.Back Door (jazz trio), a British jazz trio, drums sax and bass guitar, who played in the bar of the highest pub on the Yorkshire moors during the late 1970s. Their use of the bass guitar was ahead of its time.The Back Door (fiction), an 1897 work describing a fictional French and Russian invasion of Hong KongThe Back Door (album), a 1992 album by American band Cherish the LadiesIn serialized fiction, a backdoor is a writing technique in which the writer provides a possible solution to reverse any potentially unpopular decision that's currently being done (such as killing off a popular recurring character). See Deus ex machina.Backdoor pilot, is a method used to judge reaction to a potential new television series.To backdoor, is to do something, such as getting a job, through having some unfair advantage. For example, "I backdoored my admission to Yale; I bribed the admissions officer." See also guanxi.In Jazz Music Theory, a Backdoor Progression is a characteristic harmonic device found in many Jazz Standards.Backdoor is slang for the anus.In baseball, a backdoor pitch, usually a breaking ball, is a pitch that deceives the batter by barely crossing the outside part of the plate at the last possible moment.In basketball, a backdoor play is a common offensive attack against man-to-man defense which involves a player cutting to the basket and another player passing to the cutter behind the defender.In Surf terminology, to pull into a tube from behind the peakIn Slang Terms, means to go behind someone's back.
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Noun
1. a secret or underhand means of access (to a place or a position); "he got his job through the back door"
(hypernym) access
2. an entrance at the rear of a building
(synonym) back entrance
(hypernym) exterior door, outside door

A door in the back part of a building; hence, an indirect way.
  

<security> (Or "trap door", "wormhole"). 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. 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. The infamous RTM worm of late 1988, for example, used a back door in the BSD Unix "sendmail(8)" utility.
Ken Thompson's 1983 Turing Award lecture to the ACM revealed the existence of a back door in early Unix versions that may have qualified as the most fiendishly clever security hack of all time. The C compiler contained code that would recognise 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 *recognise 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 recognise 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 revealed this truly moby hack was published as ["Reflections on Trusting Trust", "Communications of the ACM 27", 8 (August 1984), pp. 761--763].
[Jargon File]
(1995-04-25)