Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide


NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Get The TCP/IP Guide for your own computer.
The TCP/IP Guide

Custom Search







Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  TCP/IP Key Applications and Application Protocols
           9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)
                9  TCP/IP General File Transfer Protocols (FTP and TFTP)
                     9  File Transfer Protocol (FTP)
                          9  FTP Concepts and General Operation

Previous Topic/Section
FTP Concepts and General Operation
Previous Page
Pages in Current Topic/Section
1
2
34
Next Page
FTP Control Connection Establishment, User Authentication and Anonymous FTP Access
Next Topic/Section

FTP Operational Model, Protocol Components and Key Terminology
(Page 2 of 4)

FTP Process Components and Terminology

Since the control and data functions are communicated using distinct channels, the FTP model divides the software on each device into two logical protocol components that are responsible for each channel. The protocol interpreter (PI) is a piece of software that is charged with managing the control connection, issuing and receiving commands and replies. The data transfer process (DTP) is responsible for actually sending and receiving data between the client and server. In addition to these two elements, the user FTP process includes a third component, a user interface, that interacts with the human FTP user; it is not present on the server side.

Thus, there are two server process components and three client (user) process components in FTP. These components are referred to in the FTP model by specific names, which are used in the standard to describe the detailed operation of the protocol. I plan to do the same in this section, so I will now describe more fully the components in each device of this model, which are illustrated in Figure 288.


Figure 288: File Transfer Protocol (FTP) Operational Model

FTP is a client/server protocol, with communication taking place between the User-FTP Process on the client and the Server-FTP Process on the server. Commands, replies and status information are passed between the User-PI and Server-PI over the control connection, which is established once and maintained for the session. Data is moved between devices over data connections that are set up for each transfer.

 


Previous Topic/Section
FTP Concepts and General Operation
Previous Page
Pages in Current Topic/Section
1
2
34
Next Page
FTP Control Connection Establishment, User Authentication and Anonymous FTP Access
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $



Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.