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Trng i Hc Bch Khoa Tp.HCM

Khoa Khoa Hc v K Thut My Tnh

ThS. NGUYN CAO T

E-mail:[email protected]

Biging

Mng my tnh

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TrngiHcBch Khoa Tp.HCMKhoa Khoa HcvKThutMyTnh 2011

MNG MY TNH CN BNBiging 2 - Chng 2: Tngngdng

2

Bi ging 4: Tng ng dng (tt)

Tham kho:Chng 2: Computer Networking A top-down approachKurose & Ross, 5th ed., Addison Wesley, 2010.

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3

Chng 2: Tng ng dng

2.1 Cc nguyn l ca tngng dng 2.2 Web v HTTP 2.3 FTP

2.4 Th in t SMTP, POP3, IMAP

2.5 DNS

2.6 ng dng P2P

2.7 Lp trnh Socket viTCP

2.8 Lp trnh Socket viUDP

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4

B nh m (BN) Web (my ch i din -proxy server)

thitlptrnhduyt: truycp web qua bnhm

trnhduytgitonbt truy

vn HTTP timychidin itngc trong bn:

bngitritng ngoi ra, bns truy vn

itngtmychgc,sau gili cho ngidng, ngthilulitrong bn

Mcch:pngyucucangidngmkhngcnmychgc

khch

Mych

idin

khchmy ch

gc

my chgc

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5

B nh m Web (tt)

bn lm vic va nhkhch va nh ch thng th bn thng

c ci t bi nccdv

(trng i hc, c quan)

Ti sao cn c bn Web? gim thi gian phn hi

cho truy vn n/dng

gim lu lng trong

mt ng kt ni cacng s.

cho php cc nccdvtng thm ni dung

cung cp cho ngidng

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6

V d hin thc bn

Gi thit kch thc trung bnh ca i tng =

100,000 bit

tn s t/bnh ca truy vn t trnh duytca c quan ti my ch gc = 15 ln/s

tr xoay vng t bt c quan ti btk my ch gc no = 2 s

Kt qu h/sut s dng LAN = 15% h/sut s dng trn ng truy cp =

100%

tr tng = tr Internet + trtruy cp + tr LAN

= 2 s + vi pht + vi ms

cc my ch gc

Internet

mng c quan

10 Mbps LAN

1.5 Mbpsng truy cp

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7

V d hin thc bn (tt)

nhng gii php kh d tng bng thng ca ng

truy cp ln khong 10 Mbps

kt qu

h/sut s dng LAN = 15% h/sut s dng ng truy cp

= 15%

tr tng = tr Internet+ tr truy cp + tr LAN

= 2 s + ms + ms rt tn km khi nng cp

cc my

ch gc

Internet

mng c quan

10 Mbps LAN

ng truy cp10 Mbps

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8

V d hin thc bn (tt)

gii php: ci t bn gi s tn s truy cp bn l 0.4

kt qu: 40% truy vn s c p ng ngay

lp tc bi bn 60% truy vn s c p ng bi

my ch gc hiu sut s dng ng kt ni gim

xung cn 60%, ko theo tr khngng k (khong 10 msec)

tng tr ti a = tr Internet + tr truy cp + tr LAN =.6*(2.01) secs + msec < 1.4 secs

cc my ch gc

Internet

mng c quan10 Mbps LAN

ng kt ni1.5 Mbps

bn c quan

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9

GET c iu kin

Mc ch:khng gi i tngnu nhbnc bn cp nhtmi nht ca n bn: ch r thi gian ca bn

lu bn trong truy vn HTTPIf-modified-since:

my ch: phn hi s khnggi li i tngcyu cunu bn lu l bn cp nhtmi nht:HTTP/1.0 304 Not

Modified

bn my chHTTP request msgIf-modified-since:

HTTP responseHTTP/1.0

304 Not Modified

i tngkhng

thay i

HTTP request msg

If-modified-since:

HTTP responseHTTP/1.0 200 OK

i tng

thay i

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10

Chng 2: Tng ng dng



2.5 DNS

2.6 ng dng P2P



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11

FTP: Giao thc truyn ti tp tin

truyn ti tp tin n/t my xa m hnh khch/ch

khch:l pha bt uqu trnh truyn ti ch:my xa

ftp: RFC 959

my ch ftp: cng 21

truyn ti tp tin chFTP

giao dinngi

dng FTP

khchFTP

h thng tptin cc b

h thng tp

tin xa

ngidng

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12

FTP: iu khin ring bit, kt ni d liu

Khch FTP kt ni ti my chFTP ti cng 21, giao thc truynti l TCP

khch c kim tra danh tnhthng qua kt ni iu khin

khch duyt cc th mc trnmy t xa bng cch gi cc culnh thng qua kt ni iukhin.

khi ch nhn c cu lnh

truyn ti tp, ch m kt niTCP th 2 ti khch

sau khi truyn ti xong 1 tp, chng kt ni d liu.

khchFTP

chFTP

kt ni TCP iu khincng 21

kt ni TCP dliucng 20

ch m mt kt ni TCP dliu khc truyn ti mt tpkhc.

iu khin kt ni:ngoi

tuyn (out of band) my ch FTP lu li trng

thi: th mc hin ti, thngtin v danh tnh

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13

Cc cu lnh v phn hi FTP

V d cu lnh: gi i di dng vn bn ASCIIqua kt ni iu khin

USERtn_ngi_dng

PASS mt_khu

LISTlit k danh sch cc tptrong th mc hin ti

RETR tn_tpti tp tin v

STOR tn_tpti tp tin ln

my t xa

V d m tr v m trng thi v m t (nh

trong HTTP)

331 Username OK,

password required

125 data connectionalready open;

transfer starting

425 Cant open dataconnection

452 Error writingfile

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14

Chng 2: Tng ng dng



2.5 DNS

2.6 ng dng P2P



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15

Th in t (e-mail)

Ba thnh phn chnh: cng c qun l th ngi

dng (user agent - UA) my ch th giao thc truyn ti thu n

gin: SMTP

Cng c qun l th ca ngidng

son tho, sa cha, c th vd: Eudora, Outlook, elm,

Mozilla Thunderbird

th i v th n c lutrn my ch

hp th n/dng

hng ith i

mailserver

useragent

useragent

useragent

mail

server

useragent

useragent

mailserver

useragent

SMTP

SMTP

SMTP

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16

Th in t: my ch th

My ch th hp thcha th n ca

ngi dng hng i thng ipca th

i giao thc SMTPgia cc my

ch trao i th cho nhau khch: l my ch gi th server: l my ch nhn

th

mail

server

useragent

useragent

useragent

mailserver

useragent

useragent

mailserver

useragent

SMTP

SMTP

SMTP

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MNG MY TNH CN BN

Biging 2 - Chng 2: Tngngdng17

Th in t: SMTP [RFC 2821]

s dng TCP gi th gia khch v ch, cng 25 vn chuyn trc tip: t my ch gi v my ch

nhn qu trnh vn chuyn gm 3 pha:

bt tay (cho hi) trao i thng ip kt thc

tng tc cu lnh/phn hi cu lnh: vn bn ASCII phn hi: m trng thi v m t

thng ip phi c nh dng 7-bit ASCII

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MNG MY TNH CN BN


Kch bn: Alice gi thng ip Bob1) Alice s dng UA son

th v gi [email protected]

2) UA ca Alice gi thng ipti my ch th ca c ta;th c t trong hng i

3) pha khch ca SMTP m ktni TCP ti my ch th caBob

4) khch SMTP gi th ca

Alice qua kt ni TCP5) my ch th ca Bob t th

vo hp th ca Bob6) Bob bt UA ca mnh ln

c th

useragent

mailserver

mailserver user

agent

1

2 3 45

6

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MNG MY TNH CN BN


V d tng tc SMTP

S: 220 hamburger.edu

C: HELO crepes.fr

S: 250 Hello crepes.fr, pleased to meet you

C: MAIL FROM:

S: 250 [email protected]... Sender ok

C: RCPT TO:

S: 250 [email protected] ... Recipient okC: DATA

S: 354 Enter mail, end with "." on a line by itself

C: Do you like ketchup?

C: How about pickles?

C: .S: 250 Message accepted for delivery

C: QUIT

S: 221 hamburger.edu closing connection

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MNG MY TNH CN BN


Th nghim tng tc SMTP: telnet tn_my_ch 25

nhn thy phn hi 220 t my ch g vo cc cu lnh HELO, MAIL FROM, RCPT TO, DATA,

QUIT

bng cch ny bn c th gi th m khng cn s dngcng c qun l th (UA)

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MNG MY TNH CN BN


SMTP: tng kt

SMTP s dng kt ni n nh SMTP i hi thng ip (mo

u v thn) phi dng k tASCII 7-bit

my ch SMTP s dngCRLF.CRLF xc nh imkt thc ca thng ip

So snhvi HTTP:

HTTP: lyv SMTP: yi

c hai uctngtccu

lnh/phnhididng ASCII,ccmtrngthi

HTTP: miitngcnggi trong thngipphnhicaringn

SMTP: nhiuitngcgi chung trong nhiuphncamtthngip

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MNG MY TNH CN BN


nh dng thng ip th

SMTP: giao thc trao i thin t

RFC 822: chun dng cho nhdng thng ip vn bn:

cc dng mo u, vd: To:

From:

Subject:

khc nhauph thuc vo cu lnhSMTP!

thn ni dung th, ch cha k tASCII

header

body

dngtrng

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MNG MY TNH CN BN


Giao thc truy cp th

SMTP: giao/nhn th n t my ch khc Giao thc truy cp th: ly th t my ch

POP: Post Office Protocol [RFC 1939]

kim tra danh tnh (UAmy ch) v ti v IMAP: Internet Mail Access Protocol [RFC 1730]

nhiu chc nng hn (phc tp hn) qun l th lu trn my ch

HTTP: gmail, Hotmail, Yahoo! Mail, v.v..

useragent

my ch thngi gi

useragent

SMTP SMTP accessprotocol

my ch thngi nhn

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MNG MY TNH CN BN


Giao thc POP3

pha kim tra danh tnh cu lnh ca khch:

user:khai bo tnpass:mt-khu

phn hi ca ch +OK

-ERR

pha giao dch, khch: list:lit k s th t th retr:ti th theo stt dele:xa quit: kt thc

C: list

S: 1 498

S: 2 912

S: .C: retr 1

S:

S: .

C: dele 1

C: retr 2

S: S: .

C: dele 2

C: quit

S: +OKmy ch POP3 ng ngt

S: +OK POP3 server ready

C: user bob

S: +OK

C: pass hungryS: +OKngi dng ng nhp thnh c

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MNG MY TNH CN BN


POP3 (tt) v IMAP

POP3

v d trc s dng c chti-v-xa.

Bob khng th c li thnu nh anh ta i UA

ti-v-gi li: bn saoca th s c lu trnnhiu UA

POP3 l giao thc khngtrng thi

IMAP

Gi tt c th trong mtni: trn my ch

Cho php n/dng t chcth theo th mc

IMAP gi li trng thingi dng qua cc phinlm vic: tn ca th mc cng nh

nh x gia ID ca thngip v tn th mc

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MNG MY TNH CN BN


Chng 2: Tng ng dng

2.1 Cc nguyn l ca tngng dng

2.2 Web v HTTP 2.3 FTP


2.5 DNS

2.6 ng dng P2P



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MNG MY TNH CN BN


H thng tn min DNS (Domain Name System)

Con ngi:nhiu k hiu nhndng: tn, s CMND, MSSV

My tnh v thit b trnInternet:

a ch IP (32 bit) c sdng lin lc gia mytnh

tn, vd: www.yahoo.com c s dng bi con ngi

Hi:nh x gia a ch IP vtn?

H thng tn min: c s d liu phn tnc

hin thc trong mt h thngphn cp ca nhiu my chtn min

giao thc tng ng dng

cho php my tnh, bt v mych tn min lin lc vi nhauphn giitn min (ach/tn)

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MNG MY TNH CN BN


DNS

Cc dch v DNS phn gii tn min sang a

ch IP t tn thay th cho my

tn chnh thc, v tn thayth

t tn thay th cho mych email

phn b ti nhng trang web ln thng

c nhiu my ch vi a chIP khc nhau ng sau mttn min chnh thc

Ti sao khng tp trungDNS?

DNS hng -> c mngngng hot ng

qu ti lu lng tr cao do ng

truyn di kh bo tr

khng m rngc!

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MNG MY TNH CN BN


my ch DNS gc

my ch DNS com my ch DNS org my ch DNS edu

my ch DNS

poly.edu

my ch DNS

umass.edu

my ch DNSyahoo.com

my ch DNSamazon.com

my ch DNS

pbs.org

C s d liu phn tn v phn cp

Khch mun c IP ca www.amazon.com: khch truy vn mt my ch DNS gc tm ra my ch DNS

.com khch truy vn my ch DNS .com ly a ch ca my ch

DNS amazon.com

khch truy vn my ch DNS amazon.com ly a ch IP cawww.amazon.com

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MNG MY TNH CN BN


DNS: My ch gc cc my ch tn min cc b s lin h my ch gc nu chng

khng th t phn gii tn min my ch tn min gc:

lin h nhng my ch c thm quyn nu khng tm ra nh x ly thng tin nh x tr thng tin nh x v cho cc my ch tn min cc b

13 my ch tn mingc t khp th gii

b USC-ISI Marina del Rey, CA

l ICANN Los Angeles, CA

e NASA Mt View, CA

f Internet Software C. Palo Alto,CA (and 36 other locations)

i Autonomica, Stockholm (plus

28 other locations)

k RIPE London (also 16 other locations)

m WIDE Tokyo (also Seoul,

Paris, SF)

a Verisign, Dulles, VA

c Cogent, Herndon, VA (also LA)

d U Maryland College Park, MD

g US DoD Vienna, VA

h ARL Aberdeen, MDj Verisign, ( 21 locations)

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MNG MY TNH CN BN


TLD v My ch c thm quyn

My ch tn min cp cao (Top-level domain - TLD): chu trch nhim cho com, org, net, edu, etc, v tt c cc tn

min quc gia cp cao vn, au, ca, jp. Network Solutions duy tr my ch com TLD Educause duy tr my ch edu TLD

My ch DNS c thm quyn: my ch DNS c quan, cung cp nhng nh x tin cy gia tn

min v IP cho nhng my ch ca chnh c quan (vd: Web,mail).

c th c vn hnh bi c quan hay nh CCDV

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MNG MY TNH CN BN


My ch tn min cc b

khng ph thuc mt cch r rng vo h thng phn cp mi ISP (ISP dn s, c quan, trng hc) c mt my ch

tn min cc b. cn c gi l my ch tn min mc nh

khi mt my thc hin mt truy vn DNS, truy vn s c

gi cho my ch DNS cc b ca n hot ng nh l mt my i din(proxy), chuyn tip truy vn ln

h phn cp

V d phn gii

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MNG MY TNH CN BN


my yu cucis.poly.edu

gaia.cs.umass.edu

my ch DNS gc

my ch DNS cc bdns.poly.edu

1

23

4

5

6

my ch DNS thm quyn

dns.cs.umass.edu

78

my ch DNS TLD

V d phn giitn min DNS

My ti cis.poly.edumun c IP cagaia.cs.umass.edu

truy vn lp: my ch c lin h

tr v tn ca my chkhc lin h tip

Ti khng bit tn

min ny, nhng hyhi my ch ny xem

V d phn gii

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TrngiHcBch Khoa Tp.HCM

Khoa Khoa HcvKThutMyTnh 2011

MNG MY TNH CN BN


my yu cucis.poly.edu

gaia.cs.umass.edu

my ch DNS gc

my ch DNS cc bdns.poly.edu

1

2

45

6

my ch DNS thm quyndns.cs.umass.edu

7

8

my ch DNS TLD

3truy vn qui: giao ton b cng vic

cho my ch cp caohn

ti cao?

V d phn giitn min DNS

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MNG MY TNH CN BN


DNS: nh m v cp nht th ghi

mt khi (bt k) my ch tn min nhn c gitr nh x, n s nh mli thng tin cc thng tin trong b nh m s ht hn v b xa sau

mt thi gian nht nh tn cc my ch TLD thng c nh m trong my

ch cc b v vy my ch dns gc thng t khi c truy cp

c ch cp nht/thng bo c thit k bi IETF RFC 2136

http://www.ietf.org/html.charters/dnsind-charter.html

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MNG MY TNH CN BN


Th ghi DNS

DNS:CSDL phn b cha th ti nguyn (RR)

Type=NS

tnl tn min (vd:

foo.com) gi trl tn my ca

my ch DNS c thmquyn cho min ny

nh dng RR: (tn, gi tr, loi, tgs)

Loi A (Type=A) tnl tn my gi trl a ch IP

Type=CNAME

tnl tn thay th cho tn chnhthngwww.ibm.com thc cht lservereast.backup2.ibm.com

gi trl tn chnh thng

Type=MX gi trl tn ca my ch th

lin h ti tn my tn

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MNG MY TNH CN BN


Giao thc v thng ip DNS

DNS protocol : truy vn (query)v phn hi (reply)c cngnh dng

Mo u s hiu nh danh: l mt

s 16 bit trong thng ip

truy vn, thng ip phnhi s dng chnh s c hiu:

truy vn hay phn hi mong mun qui

qui c sn phn hi l c thmquyn

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MNG MY TNH CN BN


Giao thc v thng ip DNS

Tn, loica truy vn

RRs trong phn

hi cho truy vn

th ghi dnh chomy ch c thm quyn

thng tin b sung

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Khoa Khoa

MNG MY TNH CN BN

2 2

Chn th ghi vo DNS

v d: mt cng ty mi thnh lp Network Utopia ng k tn networkuptopia.com ti DNSnh qun ltn min(vd: Network Solutions) cung cp tn, a ch IP, a ch IP ca my ch dsn c thm

quyn (s cp v th cp) nh qun l chn 2 th RR vo my ch TLD com :

(networkutopia.com, dns1.networkutopia.com, NS)

(dns1.networkutopia.com, 212.212.212.1, A)

trong my ch tn min cc b to ra th loi A cho

www.networkuptopia.com; th loi MX chonetworkutopia.com Lm sao mi ngi ly c a ch IP ca trang web

ca bn?

mmt- 02-2

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