1. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 1 Lesson 12 Transmission Control Protocol (TCP) Basics

2. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 2 Transmission Control Protocol (TCP) Basics Introduction to TCP TCP header TCP ports TCP urgent data TCP options

3. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 3 Introduction to TCP Connection-oriented Full duplex Reliable Byte stream Sender- and receiver-side flow control Segmentation of Application Layer data One-to-one delivery

4. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 4 The TCP Segment IP headerSegment TCP segment IP datagram Network Interface header Network Interface trailer Network Interface Layer frame TCP header

5. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 5 The TCP Header Source Port Destination Port Sequence Number Acknowledgment Number Data Offset Reserved Flags Window Checksum Urgent Pointer Options and Padding

6. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 6 TCP Ports Defines a location for the delivery of TCP connection data Well-known port numbers: 20 File Transfer Protocol (FTP) Server (data channel) 21 FTP Server (control channel) 23 Telnet Server 25 Simple Mail Transfer Protocol (SMTP) 69 Trivial File Transfer Protocol (TFTP) 80 Hypertext Transfer Protocol (HTTP; Web server) 139 NetBIOS Session Service 339 Lightweight Directory Access Protocol (LDAP) 445 Direct-Hosted Server Message Block (SMB) Client process may listen on dynamically allocated TCP port number

7. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 7 TCP Port Demultiplexing File Transfer Protocol (control channel) TCP Port 21 Hypertext Transfer Protocol (HTTP) TCP Port 80 Telnet Service TCP Port 23 NetBIOS Session Service TCP Port 139 TCP IP Protocol 6

8. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 8 URG ACK PSH RST SYN FIN TCP Flags

9. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 9 The TCP Pseudo Header Source IP Address Destination IP Address Unused Protocol Length = 0 = 6

10. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 10 Quantity for TCP Checksum Calculation TCP pseudo header TCP header Segment 12 bytes0 to 65,495 bytesPadding (1 byte) TCP segment

11. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 11 TCP header... Urgent data (n bytes) RFC 1122 Urgent Pointer = n - 1 RFC 793 Urgent Pointer = n Non-urgent data... TCP Urgent Data

12. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 12 TCP Options Used to extend TCP functionality Defined TCP options: End of Option List No Operation Maximum Segment Size TCP Window Scale Selective Acknowledgement (SACK) TCP Timestamps

13. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 13 End Of Option List and No Operation End of Option List A single octet with the option kind set to 0, which indicates that no other options follow No Operation A single octet with the option kind set to 1, which is used between TCP options for 4-byte alignment

14. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 14 A Multiple-Octet TCP option Option Kind Option Length Option octets...

15. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 15 IPTCPSegment IP MTU MSS TCP Maximum Segment Size

16. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 16 Option Kind Option Length Maximum Segment Size = 2 = 4 Maximum Segment Size Option

17. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 17 FDDI Rings and an Ethernet Backbone Ethernet backbone FDDI ring Ethernet switch Router Host A Host B

18. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 18 TCP Window Scale Option Option Kind Option Length Shift Count = 3

19. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 19 SACK Permitted Option Option Kind Option Length = 4 = 2

20. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 20 SACK Option Option Kind Option Length Left Edge of 1st Block Right Edge of 1st Block Left Edge of 2nd Block Right Edge of 2nd Block... = 5

21. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 21 TCP Timestamps Option Option Kind Option Length Ts Value Ts Echo Reply = 8 = 10

22. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 22 TCP Timestamp Example Host A Block 1, TS Value = 100, TS Echo Reply = 9000 Ack on Block 1, TS Value = 9020, TS Echo Reply = 100 Block 2, TS Value = 158, TS Echo Reply = 9020 Ack on Block 2, TS Value = 9053, TS Echo Reply = 158 1 2 3 4 Ack on Block 3, TS Value = 210, TS Echo Reply = 9098 Block 3, TS Value = 9098, TS Echo Reply = 158 5 6 Host B

23. Microsoft Windows Server 2003 TCP/IP Protocols and Services Technical Reference Slide: 23 Review Introduction to TCP TCP header TCP ports TCP urgent data TCP options