1. TCP/IP Protocol Suite 1 Chapter 19 Upon completion you will be able to: File Transfer: FTP and TFTP Understand the connections needed for FTP file transfer Be familiar with FTP commands and responses Know the differences between FTP and TFTP Be familiar with TFTP message types Understand TFTP flow and error control Objectives

2. TCP/IP Protocol Suite 2 19.1 FILE TRANSFER PROTOCOL (FTP) File Transfer Protocol (FTP) is the standard mechanism provided by TCP/IP for copying a file from one host to another. The topics discussed in this section include: ConnectionsCommunication Command Processing File Transfer Anonymous FTP

3. TCP/IP Protocol Suite 3 FTP uses the services of TCP. It needs two TCP connections. The well-known port 21 is used for the control connection and the well- known port 20 for the data connection. Note:

4. TCP/IP Protocol Suite 4 Figure 19.1 FTP

5. TCP/IP Protocol Suite 5 Figure 19.2 Opening the control connection

6. TCP/IP Protocol Suite 6 Figure 19.3 Creating the data connection

7. TCP/IP Protocol Suite 7 Figure 19.4 Using the control connection

8. TCP/IP Protocol Suite 8 Figure 19.5 Using the data connection

9. TCP/IP Protocol Suite 9 Figure 19.6 Command processing

10. TCP/IP Protocol Suite 10 Table 19.1 Access commands

11. TCP/IP Protocol Suite 11 Table 19.2 File management commands

12. TCP/IP Protocol Suite 12 Table 19.3 Data formatting commands

13. TCP/IP Protocol Suite 13 Table 19.4 Port defining commands

14. TCP/IP Protocol Suite 14 Table 19.5 File transfer commands

15. TCP/IP Protocol Suite 15 Table 19.5 File transfer commands (continued)

16. TCP/IP Protocol Suite 16 Table 19.6 Miscellaneous commands

17. TCP/IP Protocol Suite 17 Table 19.7 Responses

18. TCP/IP Protocol Suite 18 Table 19.7 Responses (continued)

19. TCP/IP Protocol Suite 19 Table 19.7 Responses (continued)

20. TCP/IP Protocol Suite 20 Table 19.7 Responses (continued)

21. TCP/IP Protocol Suite 21 Table 19.7 Responses (continued)

22. TCP/IP Protocol Suite 22 Figure 19.7 File transfer

23. TCP/IP Protocol Suite 23 Figure 19.8 Example 1

24. TCP/IP Protocol Suite 24 19.2 TRIVIAL FILE TRANSFER PROTOCOL (TFTP) Trivial File Transfer Protocol (TFTP) is a simple file transfer protocol without the sophisticated features of FTP. The topics discussed in this section include: MessagesConnection Data Transfer UDP Ports TFTP Example TFTP Options SecurityApplications

25. TCP/IP Protocol Suite 25 TFTP uses the services of UDP on the well-known port 69. Note:

26. TCP/IP Protocol Suite 26 Figure 19.10 Message categories

27. TCP/IP Protocol Suite 27 Figure 19.11 RRQ format

28. TCP/IP Protocol Suite 28 Figure 19.12 WRQ format

29. TCP/IP Protocol Suite 29 Figure 19.13 DATA format

30. TCP/IP Protocol Suite 30 Figure 19.14 ACK format

31. TCP/IP Protocol Suite 31 Figure 19.15 ERROR format

32. TCP/IP Protocol Suite 32 Table 19.8 Error numbers and their meanings

33. TCP/IP Protocol Suite 33 Figure 19.16 Connection establishment

34. TCP/IP Protocol Suite 34 Figure 19.17 Sorcerer’s apprentice bug

35. TCP/IP Protocol Suite 35 Figure 19.18 UDP port numbers used by TFTP

36. TCP/IP Protocol Suite 36 Figure 19.19 TFTP example