1. Understanding FTP BUPT/QMUL 2013-05-03

2. 2 Part1: Using telnet to learn FTP operations in passive mode Steps: 1. Using telnet to connect to given FTP server $ telnet ftp.mayan.cn 21 2. login using username “mayan” and password “bupt” 3. Input command “PASV”, calculate port number for data connections: port= p1×256+p2, p1 and p2 are taken from the server’s reply 4. Using another terminal to set up data connection $ telnet ftp.mayan.cn port 5. Input command “LIST”

3. 3 Part1: Using telnet to learn FTP operations in passive mode c:\>telnet ftp.mayan.cn 21 In another command window, setting up data connection 30*256+251

4. 4 In control connection: In data connection:

5. 5 in control connection in data connection Change to lab directory and list

6. 6 Download lab2.pdf in control connection in data connection

7. 7 FTP commands to try USER PASS PWD CWD LIST RETR STOR (trying on local FTP server) TYPE QUIT …

8. 8 Part2: Capture FTP commands and replies Starting wireshark set capture filter: tcp port 21 display filter: ftp In your browser ftp://ftp.mayan.cn Download a file, study the FTP commands and replies captured. Active mode is used

9. 9 Part3: Learn to use FTP user command(1)

10. 10 Learn to use FTP user command(2)

11. 11 User commands used-example D:\ftp-test> ftp ftp.mayan.cn 21 Input user name and password ftp> ls ftp> get fork.c ftp> ren fork.c fork.txt ftp> ls ftp> binary ftp> ascii ftp> quit

12. 12 Control commands and replies used when logging in

13. 13 Commands and replies used for ls Commands and replies used for get One data connection persists for one file transfer

14. 14 The procedure of ls Data connection establishment Data transmission Data connection close

15. 15 Rename fork.c fork.txt ls binary ascii Release control connection