12 UDP TCP

UDPTCPTCP TCP TCP TCP

UDPUDP (User Datagram Protocol) (Port) UDP , (Connectionless) , UDP , , UDP , ()

UDP DNS , , TCP , UDP, , , , , UDP

UDP (Multicast) (Broadcast) , UDP (Connection-Oriented) TCP,

UDP UDP Internet Explorer Outlook Express, IP UDP

Port, , TCP/IP , , TCP/IP , , IP , ,

IP Socket Address ( Socket), IP , , IP ,

IP IP , IP , (), , , , ,

16 Bits , 0 65535 IANA (Internet Assigned Numbers Authority) , 0 ~ 1023 Well-Known () , IANA , 0 ~ 1023

DNS 53, DNS 53 1024 ~ 49151 Registered , IANA , Shockwave , 1626

49152 ~ 65535 Dynamic () , Internet Explorer , Internet Explorer

Well-Known

Well-Known , , , , Telnet 23 Well-Known

, , , Windows 2000 1024~5000

Well-Known , , Web 2001, 80, , , , ,

UDP UDP UDP (Application Layer) UDP Payload, UDP Data UDP Message, UDP

UDP UDP , , UDP UDP IP (), IP PayloadUDP 8 Bytes, 4 16

UDP , UDP

UDP UDP , Byte 8, UDP , UDP IP Payload UDP UDP , , , 0

UDP , UDP UDP , , Pseudo Header (), IP IP IP IP 8 Bits, 0IP UDP

, 2 Bytes , Pseudo Header UDP 2 Bytes , 1 Byte Padding, 2 Bytes Pseudo Header UDP

1. , UDP , Pseudo Header UDP

2. Pseudo Header Padding , Pseudo Header Padding IP Payload, 3. UDP , IP , Pseudo Header Padding, , UDP

UDP , 203.74.205. 111, 80, 203.74.205.109 80 Web Server , , UDP UDP , UDP , Pseudo Header

UDP Web Site , DNS

UDP 3008 Dynamic 53 DNS Well-KnowUDP UDP , Name tw.lycosasia.com IP DNS Query

TCP UDP , TCP (Transmission Control Protocol) , TCP , UDP , TCP

TCP IP, , , ..., , ,

TCP , (UDP), , , (TCP),

TCP TCP , , , , , , TCP, ,

TCP TCP (Connection-Oriented) , TCP , TCP , (),

TCP Sliding WindowSend / Receive WindowWindow Size Byte

TCP , A B, , A B 1. A Packet 1 B, , B 2. B Packet 1 , ACK 1 AACK 1 Packet 1

3. A ACK 1 , Packet 1 Packet 2 B, , B 4. B Packet 2 , ACK 2 AACK 2 Packet 2

, A B Packet 1Packet 2 , Packet 2 , B ACK 2 AA ACK 2, B Packet 2, Packet 2 B

, TCP , , ,

Sliding Window, , A , , ACK , , , ACK

Sliding WindowSliding Window , Window, A B , Sliding Window

Sliding Window

Sliding WindowA Window , Packet 1Packet 2 Packet 3 , , B B , ACK AB Packet 1, ACK 1 A

Sliding Window

Sliding Window

Sliding Window

Send / Receive Window Sliding Window , A Sliding Window, TCP Sliding Window, Sliding Window Send Window (), Sliding Window Receive Window ()

Send / Receive WindowReceive Window , A B , B, B Receive Window, B , ACK

Send / Receive Window, 1 ~ 7 89 14 , 10 ~ 13 15 ~ 16 ,

Send / Receive WindowReceive Window

Send / Receive Window B A , 1. Packet 1, Packet 1 2. Window , ACK , Receive Window 1 Window , 1 , Window

Send / Receive Window B Packet 3Packet 1Packet 2 , B Receive Window 1. B Packet 3, Packet 3 Packet 3 Window , ACK, Receive Window

Send / Receive Window

Send / Receive Window

Send / Receive Window

Send / Receive Window

Send / Receive Window

Send / Receive Window

Send / Receive Window Receive Window , Window (ACK), , , B , (Buffer),

Window Size TCP , (Flow Control), TCP , Sliding Window ( Window Size) Window Size , Window Size 1 , , 1 ,

Window Size Window Size , , , Window Window Size , , , , Window Size

Window Size Window Size , B Receive Window , ACK A, A Send Window , B Receive Window , B , A , Receive Window B ACK , A

Byte TCP Byte , TCP Payload Byte Bytes Stream TCP Payload TCP , TCP (TCP Header)

(Sequence Number)TCP (Sequence Number) , TCP Payload 1 Byte , , A Initial Sequence Number (ISN, ), 1 B, B ACK , A TCP Payload

(Sequence Number) 1 ISN, ISN+1 (Payload, ISN , , Payload ISN+1 ) A B , 1 Byte

(Sequence Number)ISN 1000, A Payload 100200300Bytes Packet 123 B ,

(Acknowledge Number) X Y 100, X Y 100 , Y X , 100, , X 100 , Y 100 ,

(Acknowledge Number) 11-02 , A ISN 1000, 100 Bytes Packet 1 BB ACK 1 , ACK 1 1101, B A , 1Byte 1101

(Acknowledge Number), (ISN) A () , Packet 1 = ISN+1Packet 2 = ACK 1 Packet 3 = ACK 2 ...

2 TCP Payload 1 ByteACK , , TCP Payload , ,

Window Sliding Window Byte Window,

Window

, TCP , AB , A B, B ATCP

AB AB / Send / Receive Window, TCP 2 2 2 Send Window, 2 Receive Window, AB , , B ACK A , B A , ACK

,

TCP , , , TCP , Sliding Window,

TCP Bytes Stream, , Sliding Window , Byte Stream Byte TCP ,

TCP TCP TCP (TCP Connection) , TCP TCP

TCP IP B Web , B IP , ,

, (Active), (Passive)WWW , , Web , TCP , , ISN () Window Size

Handshaking, , Handshaking 3 , TCP A TCP , B , Handshaking AB , ABAB

1 A 1 TCP B, SYN (Synchronize, ) AB , AB ISN, ISN (AB) 4 Bytes, AB AB , 0

1 SYN Flag TCP , ISN, Window Size A Receive Window , Window (AB) B Send Window , AB

2 B SYN , SYN-ACK , AB ISN, ISN (AB) SYN ISN(AB), SYN-ACK ISN(AB) 1, A TCP ISN(AB)+1 1 Byte

2 SYN-ACK Flag SYN-ACK SYN Synchronize , ACK Acknowledgement, ISN (AB), Window Size B Receive Window , Window (AB) A Send Window , AB

3 A SYN-ACK , ACK , AB 1 Byte , SYN-ACK Window Size A Receive Window , Window (AB)

3 2 SYN-ACK AB ISN, AB , A , ISN(AB) 1, A B , ISN(AB)+1 1 Byte ACK Flag

TCP , , () 4 , TCP A ,

1 A 1 TCP B, FIN-ACK (FIN Finish ) , AB , AB , FSN (Final Sequence Number, ), FSN(AB)

1 AB FIN-ACK Flag AB , ACK Window Size ,

2 B ACK A, AB AB , 1 FINACK FSN(AB) 1ACK Flag

2 , AB , AB , AB , 3

3 B AB , FIN-ACK A, AB , , FSN(AB) AB 1 , A B, 2 , FSN(AB) + 1

3 FIN-ACK Flag AB ,

4 A ACK B, AB , 1 FIN-ACK FSN(AB) 1 AB , 3 FINACK FSN(AB) 1ACK Flag

TCP TCP , Sequence NumberWindow Size TCP TCP Payload, TCP Segment, TCP

TCP

TCP TCP , , AB , A TCP A TCP B TCP

TCP TCP 1 Byte B A , 1 Byte 4 Bits, TCP , 4 Bytes

TCP , Options Padding , , TCP Options Padding Options Padding 0, , TCP 20 Bytes

Acknowledge ()Synchronize () ISN, , 1 2

Urgent ()Urgent Flag 1 , B Urgent Urgent , , TCP Urgent Finish () AB 2 4 ,

Window Size BA Receive Window , AB , A AB , A Receive Window A AB , A Receive Window

2 Bytes, TCP , TCP Pseudo Header UDP

Urgent Pointer () 2 Bytes Urgent Flag 1 , TCP , Urgent Byte 3 , TCP 4 Bytes ( 0 3 Byte) Urgent

Options and PaddingOptions , TCP , MSSSACK-Permitted SACK 3 Padding TCP ( Options ) 4 Bytes

Options Option Kind 1 Byte, Options , 2 MSS4 SACK-Permitted5 SACKOption Length 1 Byte, Option , ByteOption Data, Option Option Data Option Length 2 (Option Kind Option Length 1Byte)

MSSMSS Maximum Segment Size (SYN Flag=1) , TCP AB , 1 , A MSS B, B 2 MSS A, , AB AB TCP

MSS, TCP IP Payload , TCP IP Payload, MSS MTU IP , TCP , MTU 1500 Bytes, IP (20 Bytes), TCP (20 Bytes), MSS 1460

MSS Option KindMSS 2Option LengthMSS 4 Bytes, 4Option Data 2 Bytes, MSS , Byte

SACK-Permitted AB , B ACK , A 4 100 Bytes B, B 100-199 , (200~299 300~399) , ACK A, A ACK , 100-399 , 200-399

SACK-Permitted

SACK-Permitted, TCP SACK (Selective Acknowledgement) SACK-Permitted SACK-Permitted , SACK SACK , , B SACK , A 200-399 , A

SACK-PermittedSACK-Permitted SYN Flag 1 , 1 2 AB , A 1 SACK-Permitted, A SACK , B , SACK ACK A

SACK-Permitted Option Option KindSACK-Permitted 4Option LengthSACK-Permitted 2 Bytes, 2Option Data 0

SACK ACK Flag 1 , SACK AB , B ACK A , SACK , Option Data ,

SACK Option KindSACK 5Option LengthSACK 8 Bytes ( 4 Bytes) 1 , 4 Bytes 1 , 4 Bytes

SACK 2 , 4 Bytes 2 , 4 Bytes

TCP Net Analyzer TCP , , Brower Web Server, TCP

1

1 Browser , Registered / Dynamic Web Server , 80 Browser (Initial Sequence Number), , ISN (BrowserServer)

1 TCP 20 Bytes, 8 Bytes , SYN Flag 1Browser Receive Window MSS , , MSS 1460 BytesSACK-Permitted , Browser SACK ACK

2

2 Web Server Browser Web Server (Initial Sequence Number), , ISN (BrowserServer)ISN (BrowserServer) + 1TCP 20 Bytes, 8 Bytes

2 , ACK SYN Flag 1Web Server Receive Window MSS , , MSS 1460 BytesSACK-Permitted , Web Server SACK ACK

3

3 ISN (BrowserServer) + 1ISN (BrowserServer) + 1TCP , 20 Bytes, ACK Flag 1Browser Receive Window