1. File Transfer Protocol (FTP)
The standard mechanism provided by the Internet for copying a file from one host to another.
The needs: -
Different file name conventions
Different representation of text and data
Different directory structures
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Application Layer

2. FTP (Continued…)
Differs from other client-server applications in that it establishes two connections between the client and the server. They are: -
Data connection
Used for data transfer
Consists of complex rules due to the variety of data being transferred
Control connection
Used for information control (commands and responses)
Uses very simple rules of one line command or response at a time
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Application Layer

3. FTP Model FTP client has three components User interface
Client control process
Client data transfer process
FTP server has two components
Server control process
Server data transfer process
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Application Layer

4. Figure FTP

5. FTP Connections Control connection
Maintained during the entire FTP session
Uses port 21
Involves interactive connection between user and server
Data connection
Maintained only during a file transfer
Uses port 20
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Application Layer

6. FTP Communications Communication over control connection
Uses ASCII character set, similar to SMTP
Communication over data connection
File type
Data structure
Transmission mode
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Application Layer

7. Figure 26.13 Using the control connection

8. Figure 26.14 Using the data connection

9. File Transfer
File transfer in FTP can mean one of the following three: -
Storing a file
Retrieving a file
Retrieving a list
Most operating systems provide user interface to access the services of FTP where the chosen activity is automatically converted by the interface to the corresponding FTP commands.
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Application Layer

10. Figure File transfer

11. Figure Example 1

12. List of FTP commands in DOS

13. List of FTP commands in UNIX
!, $, account, append, ascii, bell, binary, bye, case, cd, cdup, close, cr, delete, debug, dir, discount, form, get, glob, hash, help, lcd, ls, macdef, mdelete, mdir, mget, mkdir, mls, mode, mput, nmap, ntrans, open, prompt, proxy, sendport, put, pwd, quit, quote, recv, remotehelp, rename, reset, rmdir, runique, send, status, struct, sunique, tenex, trace, type, user, verbose,?

14. FTP Connection Example
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Application Layer

15. GUI FTP Example
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Application Layer