chuong2 bai4

8/6/2019 chuong2 bai4

1/45

2: Tng ng dng 1

DNS : H thng Tn minCon ngi : c th nhn dng

bng nhiu cch:

o S Chng Minh Th

o Tn, Bit danh

o S h chiu

My tnh v Router trn Interneto a ch IP (32 bit) - s dng

nh a ch cho ccdatagram

o Tn, v d nhgaia.cs.umass.edu

Q: nh x gia a ch IP v Tn?

Domain Name System:

L H c s d liu phn tnci t bi nhiu name serversphn cp

Giao thc tng ng dng :

host, routers yu cu name servers gii m tn (nh x a ch tn)

o Ch : Chc nng c bn ca

Internet hot ng nh giaothc tng ng dng

o Phc tp t ra


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2: Tng ng dng 2

DNS: H thng tn min Chc nng

o nh x (Tn min, dch v)n mt gi tr no (www.cs.yale.edu, Addr)

-> 128.36.229.30

(cs.yale.edu, Email)-> netra.cs.yale.edu

(netra.cs.yale.edu, Addr)-> 128.36.229.21

Ti sao khng s dng achIP trc tip ?

routers

DNSHostname, Service

Address

servers

clients


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2: Tng ng dng 3

DNS : Name Server (My ch Tn) Khng c server no c th lu ton

b c tn min v a ch IP tng

ng local name servers:

o Mi ISP, cng ty c local name

server (ngm nh)o Cu hi truy vn ca host v DNSs c chuyn ti local nameserver

Chc nng ca name server:o i vi host: lu a ch IP v tn

min tng ng ca host

o C th tm tn min ng vi ach IP v ngc li

Ti sao to ra mt DNSServer tp trung ?

im hng duy nht - nuname-server cht th cmng Internet s chttheo.

Khi lng giao dch tiim tp trung ln. C s d liu tp trung

xa vi nhiu ni

Bo tr d hn.

KhngM RNG c !


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2: Tng ng dng 4

DNS: t tn nh th no ? C ch t tn

o Khng gian tn (phn cp) c chia thnh cc Vng (zone)

o Mi vng c th c coi l Nhnh cacy tng qut

called a zone


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6/45

2: Tng ng dng 6

DNS : Root Name Server Local name server s hi Root name server khi khng xc nh c

nh x.

Root name server:o Hi authoritative name server nu khng tr li c

o Nhn cu tr li t authoritative name server

o Tr li local name server

b USC-ISI Marina del Rey, CAl ICANN Marina del Rey, CA

e NASA Mt View, CAf Internet Software C. Palo Alto,CA

i NORDUnet Stockholmk RIPE London

m WIDE Tokyo

a NSI Herndon, VA

c PSInet Herndon, VAd U Maryland College Park, MDg DISA Vienna, VAh ARL Aberdeen, MDj NSI (TBD) Herndon, VA

13 root name serverstrn Th gii


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2: Tng ng dng 7

DNS : V d n ginhost surf.eurecom.fr mun bit

a ch IP cagaia.cs.umass.edu

1. Hi local DNS server(dns.eurecom.fr)

2. dns.eurecom.fr hi rootname server nu cn thit

3. root name server hiauthoritative name server,dns.umass.edu nu cn

thit.requesting hostsurf.eurecom.fr

gaia.cs.umass.edu

root name server

authorititive name serverdns.umass.edulocal name serverdns.eurecom.fr

1

2

3

4

5

6


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2: Tng ng dng 8

Name Server Trung gianRoot name server:

C th khng bitauthoritative nameserver

Ch bit Name Servertrung gian, qua mitm c authoritativename server

requesting hostsurf.eurecom.fr

gaia.cs.umass.edu

root name server

local name serverdns.eurecom.fr

1

23

4 5

6

authoritative name serverdns.cs.umass.edu

intermediate name serverdns.umass.edu

7

8


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2: Tng ng dng 9

DNS: cc loi truy vn

Truy vn quy : Name server l ni gii m

a ch/tn. Nu khng t

mnh gii m c s gi yucu n name server khc. Root name server liu c b

qu ti ?

Truy vn tng tc: Nu khng phn gii c

a ch IP, gi thng ipTi khng bit, hy hi bn

ti l A. A l a ch IP caname server k tip. requesting hostsurf.eurecom.fr

gaia.cs.umass.edu

root name server

local name serverdns.eurecom.fr

1

23

4

5 6

authoritative name serverdns.cs.umass.edu

name server trung gian

dns.umass.edu

7

8

iterated query


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2: Tng ng dng 10

DNS: Lu tm v Cp nht bn ghi Khi hc c thm mt nh x, name server s ghi nh

nh x ny

o Sau mt khong thi gian, nu thnh phn no trong cachekhng c s dng th s b xa b.

C ch Cp nht v Thng bo do IETF thit k:

o RFC 2136

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


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2: Tng ng dng 11

Bn ghi DNSDNS: c s d liu phn tn lu cc Bn ghi Ti nguyn (RR)

Type=NS

o name : domain (v d

foo.com)o value : a ch IP caauthoritative name serverng vi min

nh dng RR : (name, value, type, TTL)

Type=A

o name : hostname

o value : IP address

Type=CNAME

o name : tn b danh cho mt tn

thc no : v dwww.ibm.com l tn b danhca

servereast.backup2.ibm.com

o value : tn thc

Type=MX

o value : tn ca mailserver


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2: Tng ng dng 12

Giao thc v Thng ip ca DNSGiao thc DNS : Thng ip truy vn v tr liu c chung mt

nh dng

Tiu Thng ip

identification: 16 bit.Thng ip tr li v truy

vn c cng nh danh. C:

o C query hay reply

o C mong mun quyo C chp nhn quy

o C authoritative


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2: Tng ng dng 13

DNSDNSGiaoGiao ththcc vv ThngThng iipp

Trng tn v

Kiu truy vn

Thng ip tr li

Cc bn ghi caauthoritative server

Nhng thng tin ngoi lc th hu dng


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2: Tng ng dng 14

Quan st DNS S dng lnh dig (Hoc nslookup):

o Yu cu Hi bng cu hi tng tc:%dig +trace www.cnn.com

Bt thng ip bng Etherealo DNS server lng nghe port 53


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2: Tng ng dng 15

DNS u im ? Phn cp : nng cao nng lc qun l v tng cng kh

nng m rng

Nhiu server : tng kh nng phng chng lio Xem http://www.internetnews.com/dev-news/article.php/1486981

thy Tn cng t chi Dch v (DDoS) vo h thng root servervo thng 10/2002 (9 trong 13 root server b nh tr, nhng mngch b chm i khng ng k)

o Xem http://www.cymru.com/DNS/index.html thy hiu sut

c gim st nh th no

Caching lm gim ti v gim thi gian phn hi


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2: Tng ng dng 17

Gii php Phn gii Tn kiu Linda

Nhiu xut da trn Khng gian lm vic

Phn tn (Linda) do David Gelernter a rao Intentional Naming System (INS),o Internet Indirect Infrastructure (I3)

Nt vit cc cc tuples (mt dng vector khngkiu) vo cc khng gian dng chung

Nt c cc tuple ph hp t khng gian dngchung


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2: Tng ng dng 18

Lp trnh Socket

Socket API BSD4.1 UNIX, 1981 ng dng To, S dng v ng

socket mt cch tng minh. S dng theo m hnh Client/Server Hai kiu dch v ng dng s dng

socket API:

o Truyn khng tin cyo Tin cy, hng ni, ng th t.

L giao din nm trn mytnh, do ng dng to ra vqun l, nhng HH kimsot(l ca) thng qua tin trnh va gi vnhn thng ip t cc tin

trnh ng dng khc ( trnmy tnh khc)

socket

Mc ch :Nghin cu cch xy dng ng dng client/servergiao tip qua socket


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2: Tng ng dng 19

Lp trnh Socket TCPSocket: L ca gia tin trnh ng dng v giao thc giao

vn u cui (UCP/TCP)

TCP: Dch v truyn byte tin cy t tin trnh ny sang tintrnh khc.

process

TCP with

buffers,variables

socket

Lp trnh vinkim sot

H iu Hnhkim sot

My tnh

process

TCP withbuffers,variables

socket

Lp trnh vinkim sot

My tnh

Internet

H iu Hnh

kim sot


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2: Tng ng dng 20

Lp trnh TCP SocketClient phi lin lc vi server

Tin trnh trn server phi chy

trc. Server phi to sn socket (door)

tip nhn yu cu t client.

Client trao i vi server bngcch:

To socket TCP pha client

Xc nh a ch IP, s hiu cng

ca tin trnh server.

Khi client to socket: clientTCP thit lp kt ni ti

server TCP. Khi nhn c yu cu t

client, server TCP to socketmi cho tin trnh trn server

trao i d liu vi cliento Cho php server c th

p ng yu cu ca nhiuclient.

Quan im Lp trnh ng dngTCP cung cp dch v truyn d liu tin cy

theo byte gia Client v Server


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2: Tng ng dng 21

Hng ni TCP


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2: Tng ng dng 22

Lp trnh Socket TCPV d ng dng client-server:

Client c mt dng k t t inputchun (inFromUser stream), gi tiserver qua socket (outToServer)

server c dng k t t socket server bin i dng k t (ch

thng thnh ch hoa) v gi tr vcho client.

client c dng k t bin i tsocket, in ra (inFromServer)

outToServer

to network from network

inFromServer

inFromUs

er

keyboard monitor

Process

clientSocket

input

stream

inputstream

output

stream

TCP

socket

Input stream:

sequence of bytes

into processoutput stream:sequence of bytes

out of process

Client

process

client TCPsocket


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2: Tng ng dng 23

Tng tc Socket Client/server : TCP

wait for incomingconnection requestconnectionSocket =welcomeSocket.accept()

create socket,port=x, forincoming request:welcomeSocket =

ServerSocket()

create socket,connect to hostid, port=x

clientSocket =Socket()

closeconnectionSocket

read reply fromclientSocket

close

clientSocket

Server Client

send request usingclientSocketread request from

connectionSocket

write reply toconnectionSocket

TCPconnection setup


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2: Tng ng dng 24

ServerSocket

ServerSocket()o To r a mt socket lng nghe kt ni t client

ServerSocket(int port)o To r a mt socket lng nghe kt ni t client ti cng

Port

ServerSocket(int port, int backlog) ServerSocket(int port, int backlog,

InetAddress bindAddr)

bind(SocketAddress endpoint) bind(SocketAddress endpoint, int backlog)

Socket accept()


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2: Tng ng dng 25

Socket Socket(InetAddress address, int port)

Socket(InetAddress address, int port,InetAddress localAddr, int localPort)

Socket(String host, int port)

bind(SocketAddress bindpoint)

connect(SocketAddress endpoint) connect(SocketAddress endpoint, int timeout)

InputStream get InputStream() OutputStream getOutputStream()

close()


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2: Tng ng dng 26

V d Java Client (TCP)import java.io.*;import java.net.*;class TCPClient {

public static void main(String argv[]) throws Exception{

String sentence;

String modifiedSentence;

BufferedReader inFromUser =new BufferedReader(new InputStreamReader(System.in));

Socket clientSocket = new Socket ("hostname", 6789);

DataOutputStream outToServer =new DataOutputStream(clientSocket.getOutputStream());

To input stream

To client socket,

kt ni ti server

To output stream,nh km vo socket


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2: Tng ng dng 27

V d v Java Client (TCP)

BufferedReader inFromServer =

new BufferedReader(newInputStreamReader(clientSocket.getInputStream()));

sentence = inFromUser.readLine();

outToServer.writeBytes(sentence + '\n');

modifiedSentence = inFromServer.readLine();

System.out.println("FROM SERVER: " + modifiedSentence);

clientSocket.close();

}}

To input stream,

nh km vo socket

Gi dng k t

n serverc dng k t

( bin i) do servergi v


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2: Tng ng dng 28

V d v Java Server (TCP)import java.io.*;import java.net.*;

class TCPServer {

public static void main(String argv[]) throws Exception{String clientSentence;String capitalizedSentence;

ServerSocket welcomeSocket = new ServerSocket(6789);

while(true) {

Socket connectionSocket = welcomeSocket.accept();

BufferedReader inFromClient =new BufferedReader(newInputStreamReader(connectionSocket.getInputStream()));

To Socket i cng 6789

i n khi c sockett client gi n

To input stream,nh km vo socket


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2: Tng ng dng 29

V d v Java Server (TCP)

DataOutputStream outToClient =new DataOutputStream(connectionSocket.getOutputStream());

clientSentence = inFromClient.readLine();

capitalizedSentence = clientSentence.toUpperCase() + '\n';

outToClient.writeBytes(capitalizedSentence);}

}

}

c dng k ttrong socket

To output stream,nh km vo

socket

Ghi dng k t bin i vo socket

Kt thc vng lp while,quay tr v vng lp chnh,i kt ni khc


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2: Tng ng dng 30

Phn knh trong Hng ni TCP socket c xc nh bi 4 thnh phn:

o a ch IP gi

o Cng tin trnh gi

o a ch IP nhn

o Cng tin trnh nhn

My tnh pha nhn s s dng c 4 thnh phn ny chuyn segment n socket ph hp

o Server c th ng thi h tr nhiu socket. Cc kt ni khc nhauc t ng chuyn cho cc socket tng ng


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2: Tng ng dng 31

Hng ni : Phn knh (tip)

Web clienthost A

Webserver S

Web clienthost B

Source IP: BDest IP: S

source port: xdest. port: 80

Source IP: BDest IP: S

source port: ydest. port: 80

Web server

Source IP: A

Dest IP: Ssource port: xdest. port: 80


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2: Tng ng dng 32

TCP s

lm nh th

noserver clientTCP socket space

state: listeningaddress: {*:6789, *:*}completed connection queue:sendbuf:recvbuf:

128.36.232.5128.36.230.2

TCP socket space

state: listening

address: {*:25, *:*}completed connection queue:sendbuf:recvbuf:

198.69.10.10


state: startingaddress: {198.69.10.10:1500, *:*}sendbuf:recvbuf:

local addr

local port

remote addr

remote port

%netstat -tcp a l -n


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2: Tng ng dng 33

V du : Client khi to Kt niserver client

TCP socket space

state: listeningaddress: {*:6789, *.*}completed connection queue:sendbuf:recvbuf:

128.36.232.5128.36.230.2

TCP socket space

state: listeningaddress: {*.25, *.*}completed connection queue:sendbuf:recvbuf:

198.69.10.10

state: listeningaddress: {*.25, *.*}completed connection queue:sendbuf:recvbuf:

state: connectingaddress: {198.69.10.10:1500, 128.36.232.5:6789}sendbuf:recvbuf:


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2: Tng ng dng 34

Kt ni TCP thnh cngserver client

TCP socket space

state: listeningaddress: {*:6789, *:*}completed connection queue:{128.36.232.5.6789, 198.69.10.10.1500}

sendbuf:recvbuf:

128.36.232.5128.36.230.2

TCP socket space


198.69.10.10


state: connectedaddress: {198.69.10.10:1500, 128.36.232.5:6789}sendbuf:recvbuf:


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2: Tng ng dng 35

V d Server chp nhn kt ni accept()server client

TCP socket space

state: listeningaddress: {*.6789, *:*}completed connection queue:sendbuf:recvbuf:

128.36.232.5128.36.230.2

TCP socket space

state: listening

address: {*.25, *:*}completed connection queue:sendbuf:recvbuf:

198.69.10.10

state: listening

address: {*.25, *:*}completed connection queue:sendbuf:recvbuf:

state: connected

address: {198.69.10.10.1500, 128.36.232.5:6789}sendbuf:recvbuf:

state: establishedaddress: {128.36.232.5:6789, 198.69.10.10.1500}

sendbuf:recvbuf:

Packet c gi cho socket ph hp nht!Phn knh cho gi tin da trn (IP gi, port gi, IP nhn, port nhn)


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2: Tng ng dng 36

Lp trnh Socket UDP

UDP: khng thit lp kt nigia client v server

Khng bt tay. Bn gi phi xc nh chnh

xc a ch IP v cng ca

tin trnh nhn. Server xc nh a ch IP v

cng ca bn gi t UDPdatagram nhn c.

UDP : d liu truyn i c thn ch khng theo ngth t hay mt mt.

Vi Lp trnh ngdng

UDP cung cp dch v truyn d

liu theo tng nhm byte(datagram) khng tin cy


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2: Tng ng dng 37

Tng tc Socket Client/Server : UDP

closeclientSocket

Server

read reply from

clientSocket

create socket,clientSocket =DatagramSocket()

Client

Create, address (hostid, port=x,send datagram request

using clientSocket

create socket,

port=x, forincoming request:serverSocket =DatagramSocket()

read request fromserverSocket

write reply toserverSocket

specifying clienthost address,port umber


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2: Tng ng dng 38

Example: UDPClient.java

UDP client n gin cinput tbn phm, gi

qua server v i servertr kt qu v.


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2: Tng ng dng 39

V d Java Client (UDP)

import java.io.*;import java.net.*;

class UDPClient {public static void main(String args[]) throws Exception{

BufferedReader inFromUser =

new BufferedReader(new InputStreamReader(System.in));

DatagramSocket clientSocket = new DatagramSocket();

InetAddress IPAddress = InetAddress.getByName("hostname");

byte[] sendData = new byte[1024];byte[] receiveData = new byte[1024];

String sentence = inFromUser.readLine();

sendData = sentence.getBytes();

To input stream

To client socket

Chuyn hostnamesang a ch IP

s dng DNS


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2: Tng ng dng 40

V d Java Client (UDP)

DatagramPacket sendPacket =new DatagramPacket(sendData, sendData.length, IPAddress, 9876);

clientSocket.send(sendPacket);

DatagramPacket receivePacket =new DatagramPacket(receiveData, receiveData.length);

clientSocket.receive(receivePacket);

String modifiedSentence =new String(receivePacket.getData());

System.out.println("FROM SERVER:" + modifiedSentence);clientSocket.close();}

}

To datagram cngvi d liu, di,

a ch IP, cng

Gi datagramti server

c datagramgi v t server


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2: Tng ng dng 41

V d Java Server (UDP)

import java.io.*;import java.net.*;

class UDPServer {public static void main(String args[]) throws Exception

{

DatagramSocket serverSocket = new DatagramSocket(9876);

byte[] receiveData = new byte[1024];byte[] sendData = new byte[1024];

while(true){

DatagramPacket receivePacket =new DatagramPacket(receiveData, receiveData.length);

serverSocket.receive(receivePacket);

To datagram socket cng 9876

To datagram

Nhndatagram


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2: Tng ng dng 42

V d v Java Server (UDP)

String sentence = new String(receivePacket.getData());

InetAddress IPAddress = receivePacket.getAddress();

int port = receivePacket.getPort();

String capitalizedSentence = sentence.toUpperCase();

sendData = capitalizedSentence.getBytes();

DatagramPacket sendPacket =new DatagramPacket(sendData, sendData.length, IPAddress,

port);

serverSocket.send(sendPacket);}}

}

Nhn a ch IP v

cng ca bn Gi

nh datagram

vo socket

Kt thc vng lp while,Quay tr v vng lp chnh,

i datagram khc n

To datagram gi ti client


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2: Tng ng dng 43

Lp trnh Socket : Tham kho

C-language tutorial (audio/slides): Unix Network Programming (J. Kurose),

HTTP://manic.cs.umass.edu/~amldemo/courseware/intro.

Java-tutorials: All About Sockets (Sun tutorial),

HTTP://www.javaworld.com/javaworld/jw-12-1996/jw-12-sockets.html

Socket Programming in Java: a tutorial,HTTP://www.javaworld.com/javaworld/jw-12-1996/jw-12-sockets.html


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2: Tng ng dng 44

Phn 2 : TNG KT

Cc yu cu ca Dch vtng ng dng:

o S tin cy, Bng thng, tr.

M hnh Client - Server. Cc m hnh dch v ca

tng giao vn trn Internet

o Hng kt ni, tin cy:

TCPo Khng tin cy, datagram:

UDP

Cc Giao thc c trng:o HTTP

o FTP

o SMTP, POP3

o DNS

Lp trnh Socket

o Giao tip client/servero S dng TCP, UDP socket

hc xong tng NG DNG !


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2: Tng ng dng 45

Phn 2 : TNG KT

Ch yu trao i thngip Request/Reply:

o Client yu cu thng tinhoc dch v.

o Server tr li d liucng m trng thi.

nh dng Thng ip:

o Tiu : cc trng lugi thng tin v d liu.

o D liu: thng tin ctrao i.

Trong chng ny, ch trng v GIAO THC !

Nhiu Dch v tri ngc : Thng ip mang iu khin

vs. thng ip mang d liu.

o in-based, out-of-band

Tp trung v Phn tn.

Khng trng thi v Lu trngthi.

Truyn thng ip Tin cy vKhng tin cy.

An ninh : Kim chng.

chuong2 bai4

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