NETWORKING TECHNOLOGIES-II
CHAPTER 24: THE DOMAIN NAME SYSTEM (DNS) To identify an entity, TCP/IP !oto"o#$ %$e t&e IP add!e$$, '&i"& %ni%e#y identifie$ t&e "onne"tion of a &o$t to t&e Inte!net Ho'e*e! eo#e !efe! to %$e na+e$ in$tead of add!e$$e$ e e need a $y$te+ t&at "an "a n +a a na+e to an add!e$$ o! an add!e$$ to a na+e &en t&e Inte!net 'a$ $+a##, t&e +ain- 'a$ done %$in- a &o$t fi#e T&e &o$t fi#e &ad on#y t'o "o#%+n$ "o#%+n$ "o+!i$in"o+!i$in- na+e and add!e$$ add!e$$ E*e!y &o$t "o%#d $to!e t&e &o$t fi#e on it$ di$. and %date it e!iodi"a##y f!o+ a +a$te! &o$t fi#e Today it i$ i+o$$i#e to &a*e one $in-#e &o$t fi#e to !e#ate e*e!y add!e$$ 'it& a na+e and *i"e *e!$a T&e &o$t fi#e 'o%#d e too #a!-e to $to!e in e*e!y &o$t T&e $o#%tion t&at i$ %$ed today i$ to di*ide t&i$ &%-e a+o%nt of info!+ation into $+a##e! a!t$ and $to!e ea"& a!t on a diffe!ent "o+%te! "o+%te! In t&i$ +et&od t&e &o$t t&at need$ +ain- "an "onta"t t&e "#o$e$t "o+%te! &o#din- t&e needed info!+ation T&i$ i$ t&e "on"et fo##o'ed y t&e Do+ain Na+e Sy$te+
NAMESPACE: NAMESPACE: 0 to e %na+i-%o%$ t&e na+e$ a$$i-ned to t&e +a"&ine$ $&o%#d e "a!ef%##y $e#e"ted f!o+ a na+e $a"e 'it& "o+#ete "ont!o# o*e! t&e indin-$ et'een t&e na+e$ and t&e IP add!e$$e$ T&e na+e$ $&o%#d e %ni%e e"a%$e t&e add!e$$e$ a!e %ni%e A na+e$a"e t&at +a$ ea"& add!e$$ to a %ni%e na+e "an e o!-ani1ed in t'o 'ay$: ) ) 3#at 3#at na+ na+e$a e$a"e "e:: 0 a na+e na+e in t&i t&i$ $a"e a"e i$ a $e% $e%en en"e "e of "&a! "&a!a"te a"te!!$ 'it 'it&o%t &o%t $t!%"t%!e T&e na+e$ +ay o! +ay not &a*e a "o++on $e"tion If t&ey do &a*e it &a$ no +eanin- T&e +ain di$ad*anta-e of a f#at na+e$a"e i$ t&at it "annot e %$ed in a #a!-e $y$te+ e"a%$e it +%$t e "ent!a##y "ont!o##ed to a*oid a+i-%ity and d%#i"ation 2) 2) Hie! Hie!a! a!"& "&i" i"a# a# na+e na+e$ $a" a"e: e: 0 ea"& ea"& na+e na+e i$ i$ +ade +ade of $e* $e*e! e!a# a# a!t a!t$ $ T&e T&e fi!$ fi!$tt a!t a!t "an defin definee t&e t&e nat% nat%!e !e of t&e t&e o!-a o!-ani ni1a 1ati tion on,, t&e t&e $e"on $e"ond d a!t a!t "an "an defin definee t&e t&e na+e na+e of an o!-ani1ation, and t&e t&i!d a!t "an define dea!t+ent$ in t&e o!-ani1ation and $o on A "ent!a# "ent!a# a%t&o!ity "an a$$i-n t&e a!t of t&e na+e t&at define$ define$ t&e nat%!e and na+e of t&e o!-ani1ation T&e !e$on$ii#ity of t&e !e$t of t&e na+e "an e -i*en to t&e o!-ani1ation it$e#f In t&i$ e*en i$ a!t of t&e add!e$$ i$ $a+e, t&e '&o#e add!e$$ 'i## e diffe!ent T&e na+e$ !e+ain %ni%e 'it&o%t t&e need to e a$$i-ned y a "ent!a# a%t&o!ity T&e "ent!a# a%t&o!ity "ont!o#$ on#y a!t of t&e na+e, not t&e '&o#e DOMAIN NAME SPACE To &a*e a &ie!a!"&i"a# na+e$a"e a do+ain na+e $a"e 'a$ de$i-ned In t&i$ de$i-n t&e na+e$ a!e de$i-ned in an in*e!ted t!ee $t!%"t%!e 'it& t&e !oot at t&e to T&e t!ee "an &a*e on#y 2 #e*e#$ T&e !oot -#%e$ t&e '&o#e t!ee to-et&e!5 ea"& #e*e# of t&e t!ee define$ a &ie!a!"&i"a# #e*e#
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NETWORKING TECHNOLOGIES-II 6A7E6: 0 ea"& node in t&e t!ee &a$ a #ae#, '&i"& i$ a $t!in- 'it& a +a8i+%+ of 9 "&a!a"te!$ T&e !oot #ae# i$ a n%## $t!in- DNS !e%i!e$ t&at "&i#d!en of a node &a*e diffe!ent #ae#$, '&i"& -%a!antee$ t&e %ni%ene$$ of t&e do+ain na+e$ DOMAIN NAME: 0 ea"& node in t&e t!ee &a$ a do+ain na+e A f%## do+ain na+e i$ a $e%en"e of #ae#$ $ea!ated y dot$ T&e do+ain na+e$ a!e a#'ay$ !ead f!o+ t&e node % to t&e !oot T&e #a$t #ae# i$ t&e #ae# of t&e !oot T&i$ +ean$ t&at a f%## do+ain na+e a#'ay$ end$ in a n%## #ae#, '&i"& +ean$ t&e #a$t "&a!a"te! i$ a dot e"a%$e t&e n%## $t!ini$ not&in- 3;66Y <;A6I3IED DOMAIN NAME: 0 if a #ae# i$ te!+inated y a n%## $t!in-, it i$ "a##ed a 3
DISTRI7;TION O3 NAMESPACE T&e info!+ation "ontained in t&e do+ain na+e $a"e $&o%#d e $to!ed 7%t it 'o%#d e ineffi"ient and a#$o not !e#ia#e to &a*e =%$t one "o+%te! $to!e $%"& a &%-e a+o%nt of info!+ation It i$ ineffi"ient e"a%$e !e$ondin- to !e%e$t$ f!o+ a## o*e! t&e 'o!#d #a"e$ a &ea*y #oad on t&e $y$te+ It i$ not !e#ia#e e"a%$e any fai#%!e +a.e$ t&e data ina""e$$i#e HIERARCHY O3 NAME SER>ERS T&e $o#%tion to ao*e !o#e+$ i$ to di$t!i%te t&e info!+ation a+on- +any "o+%te!$ "a##ed DNS Se!*e!$ One 'ay to do t&i$ i$ to di*ide t&e '&o#e $a"e into +any do+ain$ a$ed on t&e fi!$t #e*e# e #et t&e !oot $tand0a#one and "!eate, a$ +any do+ain$ a$ t&e!e a!e fi!$t #e*e# node$ 7%t a do+ain "!eated in t&i$ +anne! "o%#d e *e!y #a!-e5 DNS a##o'$ do+ain$ to e di*ided f%!t&e! into $+a##e! do+ain$ Ea"& $e!*e! "an e !e$on$i#e (a%t&o!itati*e) fo! eit&e! a #a!-e o! $+a## do+ain In ot&e! 'o!d$ 'e &a*e a &ie!a!"&y of $e!*e!$ ?ONE: 0 '&at a $e!*e! i$ !e$on$i#e fo! o! &a$ a%t&o!ity o*e! i$ "a##ed a 1one If a $e!*e! a""et$ !e$on$ii#ity fo! a do+ain and doe$ not di*ide t&e do+ain into $+a##e! do+ain$, t&e @do+ain and t&e @1one !efe! to t&e $a+e t&in- T&e $e!*e! +a.e$ a dataa$e "a##ed t&e 1one fi#e and .ee$ a## t&e info!+ation fo! e*e!y node %nde! t&at do+ain Ho'e*e! if a $e!*e! di*ide$ it$ do+ain$ into $% do+ain$ and de#e-ate$ a!t of it$ a%t&o!ity to ot&e! $e!*e!$, @do+ain and @1one !efe! to diffe!ent t&in-$ T&e info!+ation ao%t t&e node$ in t&e $% do+ain$ i$ $to!ed in t&e $e!*e!$ at t&e
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NETWORKING TECHNOLOGIES-II #o'e! #e*e#$ 'it& t&e o!i-ina# $e!*e! .eein- $o+e $o!t of !efe!en"e to t&e$e #o'e! #e*e# $e!*e!$ ROOT SER>ER: 0 a !oot $e!*e! i$ a $e!*e! '&o$e 1one "on$i$t$ of t&e '&o#e t!ee A !oot $e!*e! %$%a##y doe$ not $to!e any info!+ation ao%t do+ain$ %t de#e-ate$ it$ a%t&o!ity to ot&e! $e!*e!$ .eein- !efe!en"e$ to t&o$e $e!*e!$ C%!!ent#y t&e!e a!e +o!e t&an !oot $e!*e!$ ea"& "o*e!in- t&e '&o#e do+ain na+e $a"e T&e$e $e!*e!$ a!e di$t!i%ted a## a!o%nd t&e 'o!#d PRIMARY AND SECONDARY SER>ERS: 0 a !i+a!y $e!*e! i$ a $e!*e! t&at $to!e$ a fi#e ao%t t&e 1one fo! '&i"& it i$ an a%t&o!ity It i$ !e$on$i#e fo! "!eatin-, +aintaininand %datin- t&e 1one fi#e It $to!e$ t&e 1one fi#e on a #o"a# di$. A $e"onda!y $e!*e! i$ a $e!*e! t&at t!an$fe!$ t&e "o+#ete info!+ation ao%t a 1one f!o+ anot&e! $e!*e! (!i+a!y o! $e"onda!y) and $to!e$ t&e fi#e on it$ #o"a# di$. T&e $e"onda!y $e!*e! neit&e! "!eate$ no! %date$ t&e 1one fi#e If %datin- i$ !e%i!ed t&e !i+a!y $e!*e! doe$ it and t&e %dated *e!$ion i$ $ent to t&e $e"onda!y $e!*e! T&e idea i$ not to %t t&e $e"onda!y $e!*e! at a #o'e! #e*e# of a%t&o!ity %t to "!eate !ed%ndan"y fo! t&e data $o t&at if one $e!*e! fai#$, t&e ot&e! "an "ontin%e $e!*in- "#ient$ A $e!*e! "an e a !i+a!y $e!*e! fo! a $e"ifi" 1one and a $e"onda!y $e!*e! fo! anot&e! 1one &en t&e !i+a!y $e!*e! do'n#oad$ info!+ation f!o+ t&e $e"onda!y, it i$ "a##ed 1one t!an$fe!
DNS IN THE INTERNET DNS i$ a !oto"o# t&at "an e %$ed in diffe!ent #atfo!+$ In t&e Inte!net, t&e do+ain na+e $a"e i$ di*ided into t&!ee diffe!ent $e"tion$: ) Bene!i" do+ain$ 2) Co%nt!y do+ain$ ) In*e!$e do+ain$ BENERIC DOMAINS: 0 t&e -ene!i" do+ain$ define !e-i$te!ed &o$t$ a""o!din- to t&ei! -ene!i" e&a*io! Ea"& node in t&e t!ee define$ a do+ain, '&i"& i$ an inde8 to t&e do+ain na+e $a"e dataa$e 6A7E6
DESCRIPTION
"o+
Co++e!"ia# o!-ani1ation
ed%
Ed%"ationa# in$tit%tion$
-o*
Bo*e!n+ent in$tit%tion$
int
Inte!nationa# o!-ani1ation$
+i#
Mi#ita!y -!o%$
net
Net'o!. $%o!t "ente!$
o!-
Non !ofit o!-ani1ation$
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NETWORKING TECHNOLOGIES-II ae!o
Ae!o$a"e/ai!#ine$ "o+anie$
i1
7%$ine$$e$ o! fi!+$
"oo
Cooe!ati*e %$ine$$ fi!+$
info
Info!+ation $e!*i"e !o*ide!$
+%$e%+
M%$e%+$/&i$to!i"a# o!-$
na+e
Pe!$ona# na+e$
!o
P!ofe$$iona# indi*id%a# o!-$
CO;NTRY DOMAINS: 0 t&e "o%nt!y do+ain$ $e"tion fo##o'$ t&e $a+e fo!+at a$ t&e -ene!i" do+ain$ %t %$e$ t'o "&a!a"te! "o%nt!y a!e*iation$ (e- %$ fo! ;nited State$) in #a"e of t&e t&!ee "&a!a"te! o!-ani1ationa# a!e*iation$ at t&e fi!$t #e*e# Se"ond #e*e# #ae#$ "an e o!-ani1ationa# o! t&ey "an e +o!e $e"ifi", nationa# de$i-nation$ et" T&e add!e$$ an1a"%"a%$ "an e t!an$#ated to An1a "o##e-e in C%e!tino in Ca#ifo!nia in t&e ;nited State$
IN>ERSE DOMAINS (!ite t&e $a+e an$'e! if a $&o!t note on Pointe! <%e!y i$ a$.ed) T&e in*e!$e do+ain i$ %$ed to +a an add!e$$ to a na+e T&i$ +ay &aen fo! e8a+#e, '&en a $e!*e! &a$ !e"ei*ed a !e%e$t f!o+ a "#ient to do a ta$. &e!ea$ t&e $e!*e! &a$ a fi#e t&at "ontain$ a #i$t of a%t&o!i1ed "#ient$, t&e $e!*e! #i$t$ on#y t&e IP add!e$$ of t&e "#ient To dete!+ine if t&e "#ient i$ one t&e a%t&o!i1ed #i$t, it "an a$. it$ !e$o#*e! to $end a %e!y to t&e DNS $e!*e! and a$. fo! a +ain- of add!e$$ to na+e T&i$ tye of %e!y i$ "a##ed an in*e!$e o! ointe! %e!y (PTR) To &and#e a ointe! %e!y, t&e in*e!$e do+ain i$ added to t&e do+ain na+e $a"e 'it& t&e fi!$t #e*e# node "a##ed a!a (fo! &i$to!i"a# !ea$on$) T&e $e"ond #e*e# i$ a#$o one $in-#e node na+ed in0add! (fo! in*e!$e add!e$$) T&e !e$t of t&e do+ain define$ t&e IP add!e$$e$ T&e $e!*e!$ t&at &and#e t&e in*e!$e do+ain a!e a#$o &ie!a!"&i"a# To fo##o' t&e "on*ention$ of !eadin- t&e do+ain #ae#$ f!o+ t&e otto+ to t&e to, an IP add!e$$ $%"& a$ 242 i$ !ead a$ 242in0add!a!a T&i$ "onfi-%!ation +a.e$ t&e do+ain #oo. in*e!ted '&en "o+a!ed to a -ene!i" o! a "o%nt!y do+ain
A!ti"#e$ 24, 242, 24, 244, 24 f!o+ Do%-#a$ Co+e! DDNS: 0 '&en t&e DNS 'a$ de$i-ned no one !edi"ted t&at t&e!e 'o%#d e $o +any "&an-e$ +ade to add!e$$e$ In DNS '&en t&e!e i$ a "&an-e, $%"& a$ addin- a ne' &o$t, !e+o*in- a &o$t o! "&an-in- an IP add!e$$ t&e "&an-e +%$t e +ade to t&e DNS +a$te! fi#e T&e$e "&an-e$ in*o#*e a #ot of +an%a# %datin- T&e Dyna+i" Do+ain Na+e Sa"e &a$ een de*i$ed to !e$ond to t&i$ need In DDNS '&en a indin- et'een a na+e and an add!e$$ i$ dete!+ined t&e info!+ation i$ $ent %$%a##y y DHCP to a !i+a!y $e!*e! T&e !i+a!y $e!*e! %date$ t&e 1one$ T&e $e"onda!y $e!*e!$ a!e notified a"ti*e#y o! a$$i*e#y In a"ti*e notifi"ation t&e !i+a!y
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NETWORKING TECHNOLOGIES-II $e!*e! $end$ a +e$$a-e to t&e $e"onda!y ao%t t&e "&an-e In a$$i*e notifi"ation t&e $e"onda!y $e!*e!$ e!iodi"a##y "&e". fo! any "&an-e$ DNS "an eit&e! %$e ;DP o! TCP In ot& "a$e$ t&e 'e##0.no'n o!t %$ed y t&e $e!*e! i$ o!t ;DP i$ %$ed '&en t&e $i1e of t&e !e$on$e +e$$a-e i$ #e$$ t&an 2 yte$ e"a%$e +o$t ;DP a".a-e$ &a*e a 20yte $i1e #i+it If t&e $i1e i$ +o!e t&an 2 yte$ a TCP "onne"tion i$ %$ed
CHAPTER 2: APP6ICATIONS: REMOTE 6OBIN (TE6NET, R6OBIN) T&e +ain ta$. of t&e Inte!net and it$ TCP/IP !oto"o# $%ite i$ to !o*ide $e!*i"e$ fo! %$e!$ 3o! e8a+#e, %$e!$ 'ant to e a#e to !%n diffe!ent a#i"ation !o-!a+$ at a !e+ote $ite and "!eate !e$%#t$ t&at "an e t!an$fe!!ed to t&ei! #o"a# $ite One 'ay to $ati$fy t&e$e de+and$ i$ to "!eate diffe!ent "#ient0$e!*e! a#i"ation !o-!a+$ fo! ea"& de$i!ed $e!*i"e T&e ette! $o#%tion i$ a -ene!a#0%!o$e "#ient0$e!*e! !o-!a+ t&at #et$ a %$e! a""e$$ any a#i"ation !o-!a+ on a !e+ote "o+%te! In ot&e! 'o!d$ #et a %$e! #o- on to a !e+ote "o+%te! Afte! #o--in- on a %$e! "an %$e t&e $e!*i"e$ a*ai#a#e on t&e !e+ote "o+%te! and t!an$fe! t&e !e$%#t$ a". to t&e #o"a# "o+%te! TE6NET and R#o-in a!e -ene!a#0%!o$e "#ient0$e!*e! a#i"ation !o-!a+$ TE6NET i$ an a!e*iation fo! TE!+ina6 NET'o!. It i$ t&e $tanda!d TCP/IP !oto"o# fo! *i!t%a# te!+ina# $e!*i"e a$ !oo$ed y ISO TE6NET CONCEPTS Ti+e0S&a!in- En*i!on+ent: 0 TE6NET 'a$ de$i-ned at a ti+e '&en +o$t oe!atin$y$te+$ 'e!e oe!atin- in a ti+e0$&a!in- en*i!on+ent In t&i$ a #a!-e "o+%te! $%o!t$ +%#ti#e %$e!$ T&e inte!a"tion et'een a %$e! and "o+%te! o""%!$ t&!o%-& a te!+ina#, '&i"& i$ a "o+ination of .eyoa!d, +onito! and +o%$e In ti+e0$&a!in- en*i!on+ent t&e "ent!a# "o+%te! +%$t do a## of t&e !o"e$$in- &en a %$e! tye$ a "&a!a"te! on t&e .eyoa!d t&e "&a!a"te! i$ %$%a##y $ent to t&e "o+%te! and e"&oed to t&e +onito! T&i$ "!eate$ an en*i!on+ent in '&i"& ea"& %$e! &a$ t&e i##%$ion of a dedi"ated "o+%te! Re+ote 6o-in: 0 '&en a %$e! 'ant$ to a""e$$ an a#i"ation !o-!a+ o! %ti#ity #o"ated on a !e+ote +a"&ine, &e o! $&e e!fo!+$ !e+ote #o-in He!e t&e TE6NET "#ient and $e!*e! !o-!a+$ "o+e into %$e T&e %$e! $end$ t&e .ey$t!o.e$ to t&e te!+ina# d!i*e!$ '&e!e t&e #o"a# oe!atin- $y$te+ a""et$ t&e "&a!a"te!$ %t doe$ not inte!!et t&e+ T&e "&a!a"te!$ a!e $ent to t&e TE6NET "#ient, '&i"& t!an$fo!+$ t&e "&a!a"te!$ to a %ni*e!$a# "&a!a"te! $et "a##ed N>T and de#i*e!$ t&e+ to t&e #o"a# TCP/IP $ta". T&e "o++and$ o! te8t in N>T fo!+ t!a*e# t&!o%-& t&e Inte!net and a!!i*e at t&e TCP/IP $ta". at t&e !e+ote +a"&ine He!e t&e "&a!a"te!$ a!e de#i*e!ed to t&e oe!atin- $y$te+ and a$$ed to t&e TE6NET $e!*e! '&i"& "&an-e$ t&e "&a!a"te!$ to t&e "&a!a"te!$ %nde!$tanda#e y t&e !e+ote $e!*e! 7%t t&i$ "annot e done di!e"t#y e"a%$e a !e+ote
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NETWORKING TECHNOLOGIES-II oe!atin- $y$te+ i$ not de$i-ned to !e"ei*e "&a!a"te!$ f!o+ a TE6NET $e!*e! T&e $o#%tion i$ to add a ie"e of $oft'a!e "a##ed a $e%dote!+ina# d!i*e!, '&i"& !etend$ t&at t&e "&a!a"te!$ a!e "o+in- f!o+ a te!+ina# T&e oe!atin- $y$te+ t&en a$$e$ t&e "&a!a"te!$ to t&e a!o!iate a#i"ation !o-!a+$ (D!a' t&e fi-%!e 2 -i*en in Do%-#a$ Co+e! fo! t&i$ e8#anation) NETOR >IRT;A6 TERMINA6 T&e +e"&ani$+ to a""e$$ a !e+ote "o+%te! i$ "o+#e8 T&i$ i$ e"a%$e e*e!y "o+%te! and it$ oe!atin- $y$te+ a""et a $e"ia# "o+ination of "&a!a"te!$ a$ to.en$ To dea# 'it& &ete!o-eneo%$ $y$te+$ ie 'e 'ant to a""e$$ any !e+ote "o+%te! in t&e 'o!#d, 'e +%$t .no' '&at tye of "o+%te! 'e 'i## e "onne"ted to and a#$o in$ta## t&e $e"ifi" te!+ina# e+%#ato! %$ed y t&at "o+%te! TE6NET $o#*e$ t&i$ !o#e+ y definin- a %ni*e!$a# inte!fa"e "a##ed t&e Net'o!. >i!t%a# Te!+ina# >ia t&i$ "&a!a"te! $et, t&e "#ient TE6NET t!an$#ate$ t&e "&a!a"te!$ t&at "o+e f!o+ t&e #o"a# te!+ina# into t&e N>T fo!+ and de#i*e!$ t&e+ to t&e net'o!. T&e $e!*e! TE6NET, on t&e ot&e! &and t!an$#ate$ data and "o++and$ f!o+ N>T fo!+ into t&e fo!+ a""eta#e y t&e !e+ote "o+%te! N>T %$e$ t'o $et$ of "&a!a"te!$, one fo! data and one fo! "ont!o# ) Data "&a!a"te!$:0 fo! data N>T no!+a##y %$e$ '&at i$ "a##ed N>T ASCII T&i$ i$ an 0it "&a!a"te! $et in '&i"& t&e &i-&e$t o!de! it i$ 2) Re+ote "ont!o# "&a!a"te!$: 0 to $end "ont!o# "&a!a"te!$ et'een "o+%te!$ N>T %$e$ an 0it "&a!a"te! $et in '&i"& t&e &i-&e$t o!de! it i$ $et to CHARACTER
MEANINB
EO3
End of fi#e
EOR
End of !e"o!d
SE
S%0otion end
NOP
No oe!ation
DM
Data +a!.
7R
7!ea.
IP
Inte!!%t !o"e$$
AO
Ao!t o%t%t
AYT
A!e yo% t&e!eF
EC
E!a$e "&a!a"te!
E6
E!a$e #ine
BA
Bo a&ead $i-na#
S7
S%0otion e-in
I66
A-!ee to ena#e otion
ONT
Ref%$e to ena#e otion
DO
A!o*e to otion !e%e$t
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NETWORKING TECHNOLOGIES-II DONGT
Denia# of otion !e%e$t
IAC
Inte!!et ne8t "&a!a"te! a$ "ont!o#
TE6NET %$e$ on#y one TCP "onne"tion T&e $e!*e! %$e$ t&e 'e##0.no'n o!t 2 and t&e "#ient %$e$ an e&e+e!a# o!t T&e $a+e "onne"tion i$ %$ed fo! $endin- ot& data and "ont!o# "&a!a"te!$ TE6NET a""o+#i$&e$ t&i$ y e+eddin- t&e "ont!o# "&a!a"te!$ in a data $t!ea+ Ho'e*e! to di$tin-%i$& data f!o+ "ont!o# "&a!a"te!$ ea"& $e%en"e of "ont!o# "&a!a"te!$ i$ !e"eded y a $e"ia# "ont!o# "&a!a"te! "a##ed inte!!et a$ "ont!o# (IAC) TE6NET OPTIONS TE6NET #et$ t&e "#ient and $e!*e! ne-otiate otion$ efo!e o! d%!in- t&e %$e of t&e $e!*i"e Otion$ a!e e8t!a feat%!e$ a*ai#a#e to a %$e! 'it& +o!e $o&i$ti"ated te!+ina# So+e of t&e "o++on otion$ a!e: ) 7ina!y: t&i$ otion a##o'$ t&e !e"ei*e! to inte!!et e*e!y 0it "&a!a"te! !e"ei*ed e8"et IAC a$ ina!y data 2) E"&o: t&i$ otion a##o'$ t&e $e!*e! to e"&o data !e"ei*ed f!o+ t&e "#ient T&i$ +ean$ t&at e*e!y "&a!a"te! $ent y t&e "#ient to t&e $ende! 'i## e e"&oed a". to t&e $"!een of t&e "#ient te!+ina# ) S%!e$$ -o0a&ead: t&i$ otion $%!e$$e$ t&e BA "&a!a"te! 4) Stat%$: t&i$ otion a##o'$ t&e %$e! to -et t&e otion$ ena#ed at t&e $e!*e! $ite ) Ti+in- +a!.: t&i$ otion a##o'$ one a!ty to i$$%e a ti+in- +a!. t&at indi"ate$ t&at a## !e*io%$#y data &a$ een !o"e$$ed 9) Te!+ina# tye: t&i$ otion a##o'$ t&e "#ient to $end it$ te!+ina# tye ) Te!+ina# $eed: t&i$ otion a##o'$ t&e "#ient to $end it$ te!+ina# $eed ) 6ine +ode: t&i$ otion a##o'$ t&e "#ient to $'it"& to #ine +ode
A!ti"#e 2 f!o+ Do%-#a$ Co+e! CONTRO66INB THE SER>ER ) IP (inte!!%t !o"e$$): '&en a !o-!a+ i$ ein- !%n #o"a##y t&e %$e! "an inte!!%t t&e !o-!a+ if t&e !o-!a+ &a$ -one into an infinite #oo TE6NET define$ t&e IP "ont!o# "&a!a"te! t&at i$ !ead and inte!!eted a$ t&e "o++and fo! in*o.in- t&e inte!!%t f%n"tion in !e+ote +a"&ine 2) AO (ao!t o%t%t): t&i$ i$ $a+e a$ IP %t it a##o'$ t&e !o"e$$ to "ontin%e 'it&o%t "!eatin- o%t%t T&i$ i$ %$ef%# if t&e !o"e$$ &a$ anot&e! effe"t in addition to "!eatino%t%t T&e %$e! 'ant$ t&i$ effe"t %t not t&e o%t%t ) AYT (a!e yo% t&e!eF): t&i$ "ont!o# "&a!a"te! i$ %$ed to dete!+ine if t&e !e+ote +a"&ine i$ % and !%nnin- e$e"ia##y afte! a #on- $i#en"e f!o+ t&e $e!*e! &en t&i$ "&a!a"te! i$ !e"ei*ed t&e $e!*e! %$%a##y $end$ an a%di#e o! *i$%a# $i-na# to "onfi!+ t&at it i$ !%nnin4) EC (e!a$e "&a!a"te!): t&i$ i$ %$ed to e!a$e a "&a!a"te!, '&i"& inte!!et$ t&e 'o!. of a".$a"e, o! de#ete .ey in t&e #o"a# +a"&ine ) E6 (e!a$e #ine): t&i$ i$ %$ed to e!a$e t&e "%!!ent #ine in t&e !e+ote &o$t
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NETWORKING TECHNOLOGIES-II
O;T O3 7AND SIBNA66INB To +a.e "ont!o# "&a!a"te!$ effe"ti*e in $e"ia# $it%ation$, TE6NET %$e$ o%t0of0and $i-na#in- In t&i$ t&e "ont!o# "&a!a"te!$ a!e !e"eded y IAC and a!e $ent to t&e !e+ote !o"e$$ o%t of o!de! S%o$e an a#i"ation !o-!a+ !%nnin- at t&e $e!*e! $ite &a$ -one into an infinite #oo and doe$ not a""et any in%t data T&e %$e! 'ant$ to inte!!%t t&e a#i"ation !o-!a+ %t t&e !o-!a+ doe$ not !ead any data f!o+ t&e %ffe! T&e TCP at t&e $e!*e! $ite &a$ fo%nd t&at t&e %ffe! i$ f%## and &a$ $ent a $e-+ent $e"ifyin- t&at t&e "#ient 'indo' $i1e $&o%#d e 1e!o To !e+edy $%"& a $it%ation an %!-ent TCP $e-+ent $&o%#d e $ent f!o+ t&e "#ient to t&e $e!*e! T&e %!-ent $e-+ent o*e!!ide$ t&e !e-%#a! f#o'0"ont!o# +e"&ani$+ &en a TE6NET !o"e$$ 'ant$ to $end an o%t0of0and $e%en"e of "&a!a"te!$ to t&e ot&e! !o"e$$ it e+ed$ t&e $e%en"e in t&e data $t!ea+ and in$e!t$ a $e"ia# "&a!a"te! "a##ed DM (data +a!.) Ho'e*e! to fo!"e t&e ot&e! a!ty to &and#e t&e $e%en"e o%t of o!de!, it "!eate$ a TCP $e-+ent 'it& t&e %!-ent it $et and t&e %!-ent ointe! ointin- to t&e DM "&a!a"te! &en t&e !e"ei*in- TCP !e"ei*e$ t&e $e-+ent, it !ead$ t&e data and di$"a!d$ any data !e"edin- t&e "ont!o# "&a!a"te!$ &en it !ea"&e$ t&e DM "&a!a"te!, t&e !e+ainin- data a!e &and#ed no!+a##y In ot&e! 'o!d$ t&e DM "&a!a"te! i$ %$ed a$ a $yn"&!oni1ation "&a!a"te! t&at $'it"&e$ t&e !e"ei*in- TCP f!o+ t&e %!-ent +ode to t&e no!+a# +ode and !e$yn"&!oni1e$ t&e t'o end$
REMOTE 6OBIN (R#o-in) Anot&e! !e+ote #o-in "#ient0$e!*e! a#i"ation in "o++on %$e i$ R#o-in T&i$ i$ not an Inte!net $tanda!d %t 'a$ de$i-ned y 7SD ;NI to !o*ide a""e$$ to !e+ote "o+%te!$ R#o-in 'a$ o!i-ina##y de$i-ned to e %$ed on t&e ;NI oe!atin- $y$te+ a$ a $i+#e !e+ote #o-in fa"i#ity It t&e!efo!e doe$ not !o*ide otion ne-otiation T&e $e!*e! a""et$ t&e te!+ina# tye of t&e %$e! R#o-in %$e$ on#y one TCP "onne"tion T&e $e!*e! %$e$ t&e 'e##0.no'n o!t and t&e "#ient %$e$ an e&e+e!a# o!t T&e one TCP "onne"tion i$ %$ed ot& fo! data and "o++and$ CONNECTION: 0 t&e "#ient $ta!t$ t&e "onne"tion Afte! t&e %$%a# TCP "onne"tion i$ e$ta#i$&ed on o!t , t&e "#ient $end$ fo%! n%## te!+inated $t!in-$ T&e fi!$t $t!in- i$ a"t%a##y e+ty It i$ =%$t a n%## "&a!a"te! (J) 2 t&e $e"ond $t!in- define$ t&e #o-in na+e of t&e %$e! on t&e "#ient &o$t and te!+inate$ 'it& a n%## "&a!a"te! t&e t&i!d $t!in- define$ t&e #o-in na+e of t&e %$e! on t&e $e!*e! &o$t and te!+inate$ 'it& a n%## "&a!a"te! 4 t&e fo%!t& $t!in- define$ t&e na+e of t&e %$e!G$ te!+ina# fo##o'ed y a $#a$&, fo##o'ed y t&e te!+ina# $eed and te!+inated 'it& a n%## "&a!a"te!
Page 8 of 19
NETWORKING TECHNOLOGIES-II T&e $e!*e! !e$ond$ 'it& on#y one n%## "&a!a"te! 36O CONTRO6: 0 t&e o%t%t $ent y t&e $e!*e! to t&e "#ient i$ $&o'n on t&e "#ient $"!een T'o $e"ia# "&a!a"te!$ Sta!t and Sto "ont!o# t&e di$#ayin- of t&e o%t%t on t&e $"!een T&e "#ient o! t&e $e!*e! "an &and#e t&e .ey$ 6OCA6 36O CONTRO6: 0 in #o"a# f#o' "ont!o#, t&e "#ient &and#e$ t&e Sta!t and Sto .ey$ T&e "#ient doe$ not $end t&e$e t'o "&a!a"te!$ to t&e $e!*e! If t&e %$e! tye$ t&e Sto .ey t&e "#ient $to$ $&o'in- on t&e $"!een t&e o%t%t !e"ei*ed f!o+ t&e $e!*e! It %ffe!$ t&e+ &en t&e %$e! tye$ t&e Sta!t .ey t&e %ffe!ed data a!e t&en di$#ayed T&i$ i$ t&e defa%#t $ettin- REMOTE 36O CONTRO6: 0 in !e+ote f#o' "ont!o#, t&e $e!*e! &and#e$ t&e Sta!t and Sto .ey$ &en t&e $e!*e! !e"ei*e$ t&e Sto .ey it $to$ $endin- any data to t&e "#ient &en it !e"ei*e$ t&e Sta!t .ey, it $end$ t&e %ffe!ed data to t&e "#ient In !e+ote f#o' "ont!o# y t&e ti+e t&e Sto .ey !ea"&e$ t&e $e!*e! it +ay &a*e $ent a #ot of "&a!a"te!$ to t&e "#ient $"!een R#o-in 'o!.$ on#y in t&e "&a!a"te! +ode T&e data a!e $ent f!o+ t&e "#ient to t&e $e!*e! one "&a!a"te! at a ti+e Ea"& "&a!a"te! i$ t&en e"&oed to t&e %$e! te!+ina#
SEC;RITY ISS;E 7ot& TE6NET and R#o-in $%ffe! f!o+ $e"%!ity !o#e+$ A#t&o%-& ot& !e%i!e a #o-in na+e and a$$'o!d often t&i$ i$ not eno%-& A +i"!o"o+%te! "onne"ted to a !oad"a$t 6AN "an ea$i#y ea*e$d!o %$in- $nooe! $oft'a!e and "at%!e a #o-in na+e and a$$'o!d e*en if it i$ en"!yted
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NETWORKING TECHNOLOGIES-II
CHAPTER 29: APP6ICATIONS: 3I6E TRANS3ER AND ACCESS
A!ti"#e 29, 294 f!o+ Do%-#a$ Co+e! T!an$fe!!in- fi#e$ f!o+ one "o+%te! to anot&e! i$ one of t&e +o$t "o++on ta$.$ e8e"ted f!o+ a net'o!.in- o! inte!net'o!.in- en*i!on+ent T&e!e a!e "e!tain !o#e+$ t&at +%$t e dea#t 'it& in t&i$ "a$e T'o $y$te+$ +ay &a*e diffe!ent 'ay$ to !e!e$ent te8t and data 2 T'o $y$te+$ +ay &a*e diffe!ent di!e"to!y $t!%"t%!e$ T'o $y$te+$ +ay &a*e diffe!ent fi#e "on*ention$ A## of t&e$e !o#e+$ &a*e een $o#*ed y 3TP ie 3i#e T!an$fe! P!oto"o# in a *e!y $i+#e and e#e-ant a!oa"& 3TP diffe!$ f!o+ ot&e! "#ient0$e!*e! a#i"ation$ in t&at it e$ta#i$&e$ t'o "onne"tion$ et'een t&e &o$t$ One "onne"tion i$ %$ed fo! data t!an$fe! and anot&e! fo! "ont!o# info!+ation 3o! t&i$ 3TP %$e$ t'o 'e##0.no'n o!t$: o!t 2 i$ %$ed fo! t&e "ont!o# "onne"tion '&e!ea$ o!t 2 i$ %$ed fo! data "onne"tion In t&e a$i" +ode# of 3TP t&e "#ient &a$ t&!ee "o+onent$: %$e! inte!fa"e, "#ient "ont!o# !o"e$$ and t&e "#ient data t!an$fe! !o"e$$ T&e $e!*e! &a$ t'o "o+onent$: t&e $e!*e! "ont!o# !o"e$$ and $e!*e! data t!an$fe! !o"e$$ T&e "ont!o# "onne"tion !e+ain$ "onne"ted d%!in- t&e enti!e inte!a"ti*e 3TP $e$$ion T&e data "onne"tion i$ oened and t&en "#o$ed fo! ea"& fi#e t!an$fe!!ed CONNECTIONS Cont!o# Conne"tion: 0 t&e "ont!o# "onne"tion i$ "!eated in t&e $a+e 'ay a$ any ot&e! a#i"ation !o-!a+ T&e!e a!e t'o $te$ T&e $e!*e! i$$%e$ a a$$i*e oen on t&e 'e##0.no'n o!t 2 and 'ait$ fo! a "#ient 2 T&e "#ient %$e$ an e&e+e!a# o!t and i$$%e$ an a"ti*e oen T&e "onne"tion !e+ain$ oen d%!in- t&e enti!e !o"e$$ T&e $e!*i"e tye %$ed y t&e IP !oto"o# i$ +ini+i1e de#ay e"a%$e t&i$ i$ an inte!a"ti*e "onne"tion et'een a %$e! and a $e!*e! T&e %$e! tye$ "o++and$ and e8e"t$ to !e"ei*e !e$on$e$ 'it&o%t $i-nifi"ant de#ay Data Conne"tion: 0 t&e!e a!e t&!ee $te$ in*o#*ed in t&e data "onne"tion T&e "#ient i$$%e$ a a$$i*e oen %$in- an e&e+e!a# o!t T&i$ +%$t e done y t&e "#ient e"a%$e it i$ t&e "#ient t&at i$$%e$ t&e "o++and$ fo! t!an$fe!!infi#e$ 2 T&e "#ient $end$ t&i$ o!t n%+e! to t&e $e!*e! %$in- t&e PORT "o++and
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NETWORKING TECHNOLOGIES-II
T&e $e!*e! !e"ei*e$ t&e o!t n%+e! and i$$%e$ an a"ti*e oen %$in- t&e 'e##0 .no'n o!t 2 and t&e !e"ei*ed e&e+e!a# o!t n%+e!
Afte! t&e initia# "onne"tion in ot& t&e "a$e$, t&e $e!*e! !o"e$$ "!eate$ a "&i#d !o"e$$ and a$$i-n$ t&e d%ty of $e!*in- t&e "#ient to t&e "&i#d !o"e$$ %$in- an e&e+e!a# o!t
COMM;NICATION T&e 3TP "#ient and $e!*e!, '&i"& !%n on diffe!ent "o+%te!$, +%$t "o++%ni"ate 'it& ea"& ot&e! T&e$e t'o "o+%te!$ +ay %$e diffe!ent oe!atin- $y$te+$, diffe!ent "&a!a"te! $et$, diffe!ent fi#e $t!%"t%!e$ and fo!+at$ COMM;NICATION O>ER CONTRO6 CONNECTION 3TP %$e$ t&e $a+e a!oa"& a$ TE6NET o! SMTP to "o++%ni"ate a"!o$$ t&e "ont!o# "onne"tion It %$e$ t&e N>T ASCII "&a!a"te! $et Co++%ni"ation i$ a"&ie*ed t&!o%-& "o++and$ and !e$on$e$ COMM;NICATION O>ER DATA CONNECTION T&e %!o$e and i+#e+entation of t&e data "onne"tion i$ to t!an$fe! fi#e$ T&e "#ient +%$t define t&e tye of fi#e to e t!an$fe!!ed, t&e $t!%"t%!e of t&e data and t&e t!an$+i$$ion +ode T&e &ete!o-eneity !o#e+ i$ !e$o#*ed y definin- t&e$e t&!ee att!i%te$ of "o++%ni"ation 3i#e Tye: 3TP "an t!an$fe! one of t&e fo##o'in- fi#e tye$ ASCII fi#e: t&i$ i$ t&e defa%#t fo!+at fo! t!an$fe!!in- te8t fi#e$ 2 E7CDIC fi#e: if one o! ot& end$ of t&e "onne"tion %$e E7CDIC en"odin-, t&e fi#e "an e t!an$fe!!ed 'it& E7CDIC fi#e tye I+a-e fi#e: t&i$ i$ t&e defa%#t fo!+at fo! t!an$fe!!in- ina!y fi#e$
Data St!%"t%!e: 3i#e $t!%"t%!e (defa%#t): t&e fi#e &a$ no $t!%"t%!e It i$ a "ontin%o%$ $t!ea+ of yte$ 2 Re"o!d $t!%"t%!e: t&e fi#e i$ di*ided into !e"o!d$ T&i$ i$ on#y done 'it& te8t fi#e$ Pa-e $t!%"t%!e: t&e fi#e i$ di*ided into a-e$ T&e a-e$ "an e $to!ed o! a""e$$ed !ando+#y o! $e%entia##y T!an$+i$$ion +ode: St!ea+ +ode: t&i$ i$ t&e defa%#t +ode Data a!e de#i*e!ed f!o+ 3TP to TCP a$ a "ontin%o%$ $t!ea+ of yte$ TCP i$ !e$on$i#e fo! "&oin- data into $e-+ent$ of a!o!iate $i1e 2 7#o". +ode: data "an e de#i*e!ed f!o+ 3TP to TCP in #o".$ In t&i$ "a$e ea"& #o". i$ !e"eded y a yte &eade! Co+!e$$ed +ode: if t&e fi#e i$ i-, t&e data "an e "o+!e$$ed T&e "o+!e$$ion +et&od %$ed i$ %$%a##y !%n0#en-t& en"odin-
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NETWORKING TECHNOLOGIES-II
A!ti"#e 29 f!o+ Do%-#a$ Co+e! (Anony+o%$ 3TP)
T3TP (T!i*ia# 3i#e T!an$fe! P!oto"o#) T&e!e a!e o""a$ion$ '&en 'e need to $i+#y "oy a fi#e 'it&o%t t&e need of a## t&e f%n"tiona#itie$ of t&e 3TP 3o! e8a+#e, '&en a di$.#e$$ 'o!.$tation o! a !o%te! i$ ooted, 'e need to do'n#oad t&e oot$t!a and "onfi-%!ation fi#e$ He!e 'e do not need a## of t&e $o&i$ti"ation !o*ided in 3TP e =%$t need a !oto"o# t&at %i".#y "oie$ t&e fi#e$ T3TP i$ de$i-ned fo! t&e$e tye$ of fi#e t!an$fe!$ It i$ $o $i+#e t&at t&e $oft'a!e a".a-e "an fit into t&e !ead0on#y +e+o!y of a di$.#e$$ 'o!.$tation It "an e %$ed at oot$t!a ti+e T3TP "an !ead o! '!ite a fi#e fo! t&e "#ient Readin- +ean$ "oyin- a fi#e f!o+ t&e $e!*e! to t&e "#ient '&e!ea$ '!itin- +ean$ "oyin- a fi#e f!o+ t&e "#ient to t&e $e!*e! T3TP %$e$ t&e $e!*i"e$ of ;DP on t&e 'e##0.no'n o!t 9K
MESSABES T&e!e a!e fi*e tye$ of +e$$a-e$ in T3TP RR<: t&e !ead !e%e$t +e$$a-e i$ %$ed y t&e "#ient to e$ta#i$& a "onne"tion fo! !eadin- data f!o+ t&e $e!*e! 2 R<: t&e '!ite !e%e$t +e$$a-e i$ %$ed y t&e "#ient to e$ta#i$& a "onne"tion fo! '!itin- data to t&e $e!*e! DATA: t&e "#ient o! t&e $e!*e! to $end #o".$ of data %$e$ t&e data +e$$a-e T&i$ #o". +%$t e e8a"t#y 2 yte$ e8"et t&e #a$t #o"., '&i"& +%$t e et'een and yte$ A non 20yte #o". i$ %$ed a$ a $i-na# t&at t&e $ende! &a$ $end a## t&e data If t&e data &aen$ to e e8a"t#y 2 yte$ t&en t&e $ende! +%$t $end one e8t!a #o". of 1e!o yte$ to $&o' t&e end of t!an$+i$$ion 4 AC: t&e a".no'#ed-e +e$$a-e i$ %$ed y t&e "#ient o! $e!*e! to a".no'#ed-e t&e !e"eit of a data #o". ERROR: t&e "#ient o! $e!*e! %$e$ t&e e!!o! +e$$a-e '&en a "onne"tion "annot e e$ta#i$&ed o! '&en t&e!e i$ a !o#e+ d%!in- data t!an$+i$$ion It "an e $ent a$ a ne-ati*e !e$on$e to RR< o! R< CONNECTION ESTA76ISHMENT: 0 "onne"tion e$ta#i$&+ent fo! !eadin- fi#e$ i$ diffe!ent f!o+ "onne"tion e$ta#i$&+ent fo! '!itin- fi#e$ Readin-: to e$ta#i$& a "onne"tion fo! !eadin-, t&e T3TP "#ient $end$ a RR< +e$$a-e T&e na+e of t&e fi#e and t&e t!an$+i$$ion +ode i$ defined in t&i$ +e$$a-e If t&e $e!*e! "an t!an$fe! t&e fi#e it !e$ond$ o$iti*e#y 'it& a DATA +e$$a-e e#$e 'i## !e$ond ne-ati*e#y 'it& an ERROR +e$$a-e 2 !itin-: to e$ta#i$& a "onne"tion fo! '!itin-, t&e T3TP "#ient %$e$ t&e R< +e$$a-e T&e na+e of t&e fi#e and t&e t!an$+i$$ion +ode i$ defined in t&i$ +e$$a-e If t&e $e!*e! "an a""et a "oy of t&e fi#e, it !e$ond$ 'it& an AC +e$$a-e e#$e 'it& an ERROR +e$$a-e
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NETWORKING TECHNOLOGIES-II
CONNECTION TERMINATION: 0 afte! t&e enti!e fi#e i$ t!an$fe!!ed, t&e "onne"tion +%$t e te!+inated T3TP doe$ not &a*e a $e"ia# +e$$a-e fo! te!+ination Te!+ination i$ a""o+#i$&ed y $endin- t&e #a$t #o". of data, '&i"& a!e #e$$ t&an 2 yte$
ERROR CONTRO6 T&e T3TP e!!o!0"ont!o# +e"&ani$+ i$ diffe!ent f!o+ t&o$e of ot&e! !oto"o#$ It i$ $y++et!i", '&i"& +ean$ t&at t&e $ende! and t&e !e"ei*e! ot& %$e t&e "on"et of ti+e0 o%t$ T&e $ende! %$e$ a ti+e o%t fo! data +e$$a-e$5 t&e !e"ei*e! %$e$ ti+e0o%t fo! a".no'#ed-e+ent +e$$a-e$ If a data +e$$a-e i$ #o$t t&en t&e $ende! !et!an$+it$ it afte! ti+e0o%t e8i!ation If an a".no'#ed-+ent i$ #o$t t&e !e"ei*e! !et!an$+it$ it afte! ti+e0o%t e8i!ation T&i$ -%a!antee$ a $+oot& oe!ation E!!o! "ont!o# i$ needed in 4 $it%ation$: Da+a-ed +e$$a-e: if a #o". of data i$ da+a-ed, t&e !e"ei*e! dete"t$ it and t&e #o". i$ di$"a!ded T&e $ende! 'ait$ fo! t&e a". and doe$ not !e"ei*e 'it&in t&e ti+e0o%t and &en"e !et!an$+it$ it 2 6o$t +e$$a-e: if a #o". i$ #o$t it ne*e! !ea"&e$ t&e !e"ei*e! and no a". i$ $ent T&e $ende! !e$end$ t&e #o". afte! ti+e0o%t 6o$t a".no'#ed-e+ent: if an a".no'#ed-e+ent i$ #o$t, 'e &a*e t'o $it%ation$ If t&e ti+e! of t&e !e"ei*e! +at%!e$ efo!e t&e ti+e! of t&e $ende!, t&e !e"ei*e! !et!an$+it$ t&e a".no'#ed-+ent ot&e!'i$e t&e $ende! !e$end$ t&e data 4 D%#i"ate +e$$a-e: t&e !e"ei*e! t&!o%-& t&e #o". n%+e! "an dete"t d%#i"ation of #o".$ In any "a$e, t&e #o". i$ a".no'#ed-ed on"e a-ain y t&e !e"ei*e!
SORCERERGS APPRENTICE 7;B: 0 a#t&o%-& t&e f#o' and e!!o! "ont!o# +e"&ani$+ in T3TP i$ $y++et!i", it "an #ead to a !o#e+ .no'n a$ So!"e!e!G$ a!enti"e %-, na+ed fo! t&e "a!toon "&a!a"te! '&o "on=%!e$ % a +o t&at "ontin%o%$#y !e#i"ate$ it$e#f T&i$ 'i## &aen if t&e AC +e$$a-e fo! a a".et i$ de#ayed %t not #o$t In t&i$ $it%ation e*e!y $%""eedin- #o". i$ $ent t'i"e, and e*e!y $%""eedin- a". i$ !e"ei*ed t'i"e S%o$e fo! e8a+#e, t&e fift& a". i$ de#ayed Afte! t&e ti+e0o%t t&e $ende! !e$end$ t&e fift& #o"., '&i"& 'i## e a".no'#ed-ed y t&e !e"ei*e! a-ain T&e $ende! !e"ei*e$ t'o a".$ fo! t&e fift& #o"., '&i"& t!i--e!$ it to $end t&e $i8t& #o". t'i"e T&e !e"ei*e! !e"ei*e$ t&e $i8t& #o". t'i"e and a-ain $end$ t'o a".$ And t&e !o#e+ -oe$ on SEC;RITY: 0 one i+o!tant oint ao%t T3TP i$ t&at t&e!e i$ no !o*i$ion fo! $e"%!ity T&e!e i$ no %$e! identifi"ation o! a$$'o!d One $e"%!ity +ea$%!e i$ to #i+it t&e a""e$$ of T3TP to non"!iti"a# fi#e$ Anot&e! 'ay i$ to add $e"%!ity y %$in- anot&e! a#i"ation !o-!a+ $%"& a$ TE6NET in "on=%n"tion 'it& T3TP T&e %$e! +%$t fi!$t a""e$$ TE6NET and it 'i## "&e". t&e a""e$$ !i-&t$ of t&e %$e! T3TP i$ *e!y %$ef%# fo! a$i" fi#e t!an$fe! '&e!e $e"%!ity i$ not a i- i$$%e It$ +ain a#i"ation i$ in "on=%n"tion 'it& t&e 7OOTP o! DHCP !oto"o#$ T3TP !e%i!e$ on#y a
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NETWORKING TECHNOLOGIES-II $+a## a+o%nt of +e+o!y and %$e$ t&e $e!*i"e$ of ;DP and IP It "an e ea$i#y "onfi-%!ed in ROM
A!ti"#e$ 292, 29, 294, 29 f!o+ Do%-#a$ Co+e! (N3S)
CHAPTER 2: APP6ICATIONS: E6ECTRONIC MAI6 (SMTP, POP, IMAP, MIME) TO 7E DONE 3ROM DO;B6AS COMER
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NETWORKING TECHNOLOGIES-II APP6ICATIONS: OR6D IDE E7 (HTTP)
T&e e "on$i$t$ of a #a!-e $et of do"%+ent$ "a##ed e Pa-e$, '&i"& a!e a""e$$i#e o*e! t&e Inte!net Ea"& e a-e i$ "#a$$ified a$ a &ye!+edia do"%+ent T'o +ain %i#din- #o".$ a!e %$ed to i+#e+ent t&e e on to of t&e -#oa# Inte!net A e !o'$e! "on$i$t$ of an a#i"ation !o-!a+ t&at a %$e! in*o.e$ to a""e$$ and di$#ay a e a-e T&e !o'$e! e"o+e$ a "#ient t&at "onta"t$ t&e a!o!iate e $e!*e! to otain a "oy of t&e $e"ified a-e T&e Hye!te8t T!an$fe! P!oto"o# (HTTP) i$ a !oto"o# %$ed +ain#y to a""e$$ data on t&e o!#d ide e T&e !oto"o# t!an$fe!$ data in t&e fo!+ of #ain te8t, &ye!te8t, a%dio, *ideo and $o on It i$ "a##ed t&e Hye!te8t T!an$fe! !oto"o# e"a%$e it$ effi"ien"y a##o'$ it$ %$e in a &ye!te8t en*i!on+ent '&e!e t&e!e a!e !aid =%+$ f!o+ one do"%+ent to anot&e! HTTP f%n"tion$ #i.e a "o+ination of SMTP and 3TP It i$ $i+#e! t&an 3TP e"a%$e it %$e$ on#y one TCP "onne"tion ('e## .no'n o!t ) T&e idea of HTTP i$ *e!y $i+#e A "#ient $end$ a !e%e$t, '&i"& #oo.$ #i.e +ai# to t&e $e!*e! T&e $e!*e! $end$ t&e !e$on$e '&i"& #oo.$ a #i.e a +ai# !e#y to t&e "#ient T&e !e%e$t and !e$on$e +e$$a-e$ "a!!y data in t&e fo!+ of #ette! 'it& MIME #i.e fo!+at
CHARACTERISTICS O3 HTTP: 0 T&e !oto"o# %$ed fo! "o++%ni"ation et'een a !o'$e! and a e $e!*e! o! et'een inte!+ediate +a"&ine$ and e $e!*e!$ i$ .no'n a$ Hye!te8t T!an$fe! P!oto"o# A#i"ation #e*e#: HTTP oe!ate$ at t&e a#i"ation #e*e# It a$$%+e$ a !e#ia#e "onne"tion o!iented t!an$o!t !oto"o# $%"& a$ TCP Re%e$t/Re$on$e: on"e a $e$$ion &a$ een e$ta#i$&ed one $ide +%$t $end a !e%e$t to '&i"& t&e ot&e! $ide !e$ond$ State#e$$: ea"& HTTP !e%e$t i$ $e#f0"ontained T&e $e!*e! doe$ not .ee &i$to!y of !e*io%$ !e%e$t$ o! $e$$ion$ 7i0di!e"tiona# t!an$fe!: in +o$t "a$e$ a !o'$e! !e%e$t$ a e a-e and t&e $e!*e! t!an$fe!$ a "oy to t&e !o'$e! HTTP a##o'$ t!an$fe! f!o+ t&e !o'$e! to t&e $e!*e! in "a$e$ of $%+ittin- a fo!+ S%o!t fo! "a"&in-: to i+!o*e !e$on$e ti+e a !o'$e! "a"&e$ a "oy of ea"& e a-e i$ !et!ie*e$ S%o!t fo! inte!+edia!ie$: HTTP a##o'$ a +a"&ine a#on- t&e at& et'een a !o'$e! and $e!*e! to a"t a$ a !o8y $e!*e! t&at "a"&e$ e a-e$ and an$'e!$ a !o'$e!G$ !e%e$t f!o+ it$ "a"&e
HTTP TRANSACTION T&e!e a!e t'o -ene!a# tye$ of HTTP +e$$a-e$:
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NETWORKING TECHNOLOGIES-II HTTP RE<;EST 2 HTTP RESPONSE RE<;EST MESSABES: A !e%e$t +e$$a-e "on$i$t$ of a !e%e$t #ine, a &eade! and $o+eti+e$ ody a#$o T&e !e%e$t #ine define$ t&e !e%e$t tye, !e$o%!"e (;R6) and HTTP *e!$ion Re%e$t tye: in *e!$ion of HTTP, $e*e!a# !e%e$t tye$ a!e defined T&e !e%e$t tye "ate-o!i1e$ t&e !e%e$t +e$$a-e$ into $e*e!a# +et&od$ BET: 0 t&e BET +et&od i$ %$ed '&en t&e "#ient 'ant$ to !et!ie*e a do"%+ent f!o+ t&e $e!*e! T&e add!e$$ of t&e do"%+ent i$ defined in t&e ;R6 T&e $e!*e! !e$ond$ 'it& t&e "ontent$ of t&e do"%+ent in t&e ody of t&e !e$on$e +e$$a-e %n#e$$ t&e!e i$ an e!!o! HEAD: 0 t&i$ i$ %$ed '&en t&e "#ient 'ant$ $o+e info!+ation ao%t a do"%+ent %t not t&e do"%+ent it$e#f It i$ $i+i#a! to BET, %t t&e !e$on$e f!o+ t&e $e!*e! doe$ not "ontain a ody POST: 0 t&i$ i$ %$ed '&en t&e "#ient !o*ide$ $o+e info!+ation to t&e $e!*e! It "an e %$ed to $end in%t to t&e $e!*e! P;T: 0 t&e "#ient to !o*ide a ne' o! !e#a"e+ent do"%+ent to e $to!ed on t&e $e!*e! %$e$ t&i$ +et&od T&e do"%+ent i$ in"#%ded in t&e ody of t&e !e%e$t and 'i## e $to!ed in t&e #o"ation defined y t&e ;R6 COPY: 0 t&i$ +et&od i$ %$ed to "oy a fi#e to anot&e! #o"ation T&e #o"ation of t&e $o%!"e fi#e i$ -i*en in t&e !e%e$t #ine MO>E: 0 it i$ %$ed to +o*e a fi#e to anot&e! #o"ation DE6ETE: 0 t&i$ +et&od i$ %$ed to !e+o*e a do"%+ent on t&e $e!*e! 6IN: 0 t&i$ +et&od i$ %$ed to "!eate a #in. o! #in.$ f!o+ a do"%+ent to anot&e! #o"ation T&e #o"ation of t&e fi#e i$ -i*en in t&e !e%e$t #ine OPTION: 0 t&e otion +et&od i$ %$ed y t&e "#ient to a$. t&e $e!*e! ao%t a*ai#a#e otion$
;nifo!+ Re$o%!"e 6o"ato!$ (;R6): 0 a "#ient t&at 'ant$ to a""e$$ a e a-e need$ an add!e$$ To fa"i#itate t&e a""e$$ of do"%+ent$ di$t!i%ted t&!o%-&o%t t&e 'o!#d, HTTP %$e$ t&e "on"et of #o"ato!$ T&e ;R6 i$ a $tanda!d fo! $e"ifyin- any .ind of info!+ation on t&e Inte!net T&e -ene!a# $"&e+e of an ;R6 i$ a$ fo##o'$:
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NETWORKING TECHNOLOGIES-II $"&e+e://&o$tna+e L: o!t / at& L5 a!a+ete!$ LF %e!y He!e $"&e+e i$ t&e !oto"o# %$ed to !et!ie*e t&e do"%+ent T&e +o$t "o++on one$ a!e Bo&e!, 3TP, HTTP, and TE6NET T&e &o$tna+e i$ t&e "o+%te! '&e!e t&e info!+ation i$ $to!ed a#t&o%-& t&e na+e of t&e "o+%te! "an e a#ia$ T&e ;R6 "an otiona##y "ontain t&e o!t n%+e! of t&e $e!*e! a!a+ete!$ i$ an otiona# $t!in- t&at $e"ifie$ additiona# a!a+ete!$ $%#ied y t&e "#ient %e!y i$ an otiona# $t!in- %$ed '&en t&e !o'$e! $end$ a %e$tion Pat& i$ t&e at&na+e of t&e fi#e '&e!e t&e info!+ation i$ #o"ated T&e !oto"o# $tanda!d$ di$tin-%i$& et'een t&e a$o#%te fo!+ of an ;R6 and !e#ati*e fo!+ A !e#ati*e ;R6, i$ $e#do+ $een y a %$e! i$ on#y +eanin-f%# '&en t&e $e!*e! &a$ a#!eady een dete!+ined ie t&e $e!*e! i$ i+#i"it#y .no'n
>e!$ion: 0 a#t&o%-& t&e +o$t "%!!ent *e!$ion of HTTP i$ , HTTP *e!$ion$ and K a!e $ti## in %$e
RESPONSE MESSABE: 0 a !e$on$e +e$$a-e "on$i$t$ of a $tat%$ #ine, a &eade! and $o+eti+e$ a ody Stat%$ #ine: 0 t&e $tat%$ #ine define$ t&e $tat%$ of t&e !e$on$e +e$$a-e It "on$i$t$ of t&e HTTP *e!$ion, a $tat%$ "ode and a $tat%$ &!a$e HTTP *e!$ion i$ t&e $a+e a$ t&e fie#d in t&e !e%e$t #ine Stat%$ "ode: 0 t&e $tat%$ "ode fie#d "on$i$t$ of t&!ee di-it$ T&e "ode$ in t&e !an-e a!e on#y info!+ationa#5 t&e "ode$ in t&e 2 !an-e indi"ate a $%""e$$f%# !e%e$t T&e "ode$ in t&e !an-e !edi!e"t t&e "#ient to anot&e! ;R6 and t&e "ode$ in t&e 4 !an-e indi"ate an e!!o! at t&e "#ient $ide 3ina##y "ode$ in t&e !an-e indi"ate an e!!o! at t&e $e!*e! $ide
Stat%$ &!a$e: 0 t&i$ fie#d e8#ain$ t&e $tat%$ "ode in t&e te8t fo!+at
PERSISTENT >ERS;S NON PERSISTENT CONNECTION HTTP *e!$ion $e"ified a non0e!$i$tent "onne"tion '&i#e a e!$i$tent "onne"tion i$ t&e defa%#t in *e!$ion Non0e!$i$tent "onne"tion T&e "#ient oen$ a TCP "onne"tion and $end$ a !e%e$t 2 T&e $e!*e! $end$ t&e !e$on$e and "#o$e$ t&e "onne"tion T&e "#ient !ead$ t&e data %nti# it en"o%nte!$ an end0of0fi#e +a!.e!5 it t&en "#o$e$ t&e "onne"tion
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NETWORKING TECHNOLOGIES-II In t&i$ $t!ate-y fo! N diffe!ent i"t%!e$ in diffe!ent fi#e$, t&e "onne"tion +%$t e oened and "#o$ed N ti+e$ T&i$ $t!ate-y i+o$e$ a &i-& o*e!&ead and !e%i!e$ a $#o' $ta!t !o"ed%!e ea"& ti+e a "onne"tion i$ oened Pe!$i$tent "onne"tion In t&i$ "onne"tion t&e $e!*e! #ea*e$ t&e "onne"tion oen fo! +o!e !e%e$t$ afte! $endin- a !e$on$e T&e $e!*e! "an "#o$e t&e "onne"tion at t&e !e%e$t of a "#ient o! if a ti+eo%t &a$ een !ea"&ed A !o'$e! %$in- a e!$i$tent "onne"tion "an f%!t&e! oti+i1e y ie#inin!e%e$t$ It i$ e$e"ia##y att!a"ti*e in $it%ation$ '&e!e +%#ti#e i+a-e$ +%$t e !et!ie*ed fo! a a-e In t&i$ "onne"tion t&e $ende! %$%a##y $end$ t&e #en-t& of t&e data 'it& ea"& !e$on$e $o a$ to identify t&e e-innin- and end ite+ $ent in ea"& "onne"tion Ho'e*e! t&e!e a!e $o+e o""a$ion$ '&en t&e $ende! doe$ not .no' t&e #en-t& of t&e data T&i$ i$ t&e "a$e '&en a do"%+ent i$ "!eated dyna+i"a##y o! a"ti*e#y In t&e$e "a$e$ t&e $e!*e! info!+$ t&e "#ient t&at t&e #en-t& i$ not .no'n and "#o$e$ t&e "onne"tion afte! $endin- t&e data $o t&e "#ient .no'$ t&at t&e end of t&e data &a$ een !ea"&ed
A!ti"#e$ 22, 2, 24, 2 f!o+ Do%-#a$ Co+e!
NET BENERATION: IP >e!$ion 9 ("o%#d e a$.ed in >i*a) T&e net'o!. #aye! !oto"o# in t&e TCP/IP !oto"o# $%ite i$ "%!!ent#y IP*4 a#t&o%-& IP*4 i$ 'e## de$i-ned, data "o++%ni"ation &a$ e*o#*ed $in"e t&e in"etion of IP*4 in t&e K$ it &a$ $o+e defi"ien"ie$ t&at +a.e it %n$%ita#e fo! t&e fa$t -!o'in- Inte!net in"#%din- t&e fo##o'in-: t&e +et&od of add!e$$in- &a$ de#eted t&e add!e$$ $a"e of IP*4 and $oon t&e!e 'i## not e any add!e$$e$ #eft to a$$i-n to any ne' $y$te+ t&at 'ant$ to e "onne"ted to t&e Inte!net 2 t&e Inte!net +%$t a""o++odate !ea# ti+e a%dio and *ideo t!an$+i$$ion T&i$ tye of t!an$+i$$ion !e%i!e$ +ini+%+ de#ay $t!ate-ie$ and !e$e!*ation of !e$o%!"e$ not !o*ided in IP*4 de$i-n t&e Inte!net +%$t a""o++odate en"!ytion and a%t&enti"ation of data fo! $o+e a#i"ation$ No en"!ytion o! a%t&enti"ation i$ !o*ided in IP*4 To o*e!"o+e t&e$e defi"ien"ie$, IP*9 a#$o .no'n a$ IPn- (Inte!net'o!.in- !oto"o#, ne8t -ene!ation) 'a$ !oo$ed and i$ no' a $tanda!d In IP*9, t&e Inte!net !oto"o# 'a$ e8ten$i*e#y +odified to a""o++odate t&e %nfo!e$een -!o't& of t&e Inte!net Re#ated !oto"o#$ $%"& a$ ICMP 'e!e a#$o +odified Ot&e! !oto"o#$ in t&e net'o!. #aye! $%"& a$ ARP, RARP 'e!e eit&e! de#eted o! in"#%ded Ro%tin- !oto"o#$ $%"& a$ RIP, 'e!e a#$o $#i-&t#y +odified to a""o++odate $%"& "&an-e$
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NETWORKING TECHNOLOGIES-II T&e ne8t -ene!ation IP, o! IP*9 &a$ $o+e ad*anta-e$ o*e! IP*4 t&at "an e $%++a!i1ed a$ e#o': an IP*9 add!e$$ i$ 2 it$ #on- Co+a!ed 'it& t&e 20it add!e$$ of IP*4 t&i$ i$ a &%-e in"!ea$e in t&e add!e$$ $a"e (2 K9) 2 IP*9 %$e$ a ne' &eade! fo!+at in '&i"& otion$ a!e $ea!ated f!o+ t&e a$e &eade! and in$e!ted '&en needed et'een t&e a$e &eade! and t&e %e! #aye! data T&i$ $i+#ifie$ and $eed$ % t&e !o%tin- !o"e$$ e"a%$e +o$t of t&e otion$ do not need to e "&e".ed y t&e !o%te!$ IP*9 i$ de$i-ned to a##o' t&e e8ten$ion of t&e !oto"o# if !e%i!ed y ne' te"&no#o-ie$ o! a#i"ation$ 4 in IP*9 t&e tye of $e!*i"e fie#d &a$ een !e+o*ed %t a +e"&ani$+ "a##ed f#o' #ae# &a$ een added to ena#e t&e $o%!"e to !e%e$t $e"ia# &and#in- of t&e a".et t&e en"!ytion and a%t&enti"ation otion$ in IP*9 !o*ide "onfidentia#ity and inte-!ity of t&e a".et
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