File Transfer Protocol (FTP)

Created by Ajay Nemkul Shrestha

1. F ile T ransfer P rotocol( FTP ) P resentation B y: A smita W agle P raful N epal A jay N emkul S hrestha

2. Contents I ntroduction OSI M odule P rotocol H istory O f FTP S erver U sage O f FTP M erits O f FTP D emerits O f FTP

3. I ntroduction T o FTP F ile T ransfer P rotocol( FTP ) is standard network protocol used to transfer computer files between a client and server on a computer network. I t is built on a client-server model architecture and uses separate control and data connection between the client and the server which operates under the application layer of O pen S ystem I nterconnection ( OSI ) model.

4. OSI M odel S.N. Layer Type Description 1 Application Layer This is an abstraction layer that specifies the shared protocols and interface methods used by hosts in a communications network that contains services needed by application software or OS to communicate using Data on the network. (e.g. FTP, AFP, APPC etc) 2 Presentation Layer This is responsible for the delivery and formatting of information to the application layer for further processing or display. (e.g. ACSE, ROSE, CCR) and Specific Application Service Element (SASE) (e.g. FTAM, VT, JTM) 3 Session Layer This provides the mechanism for opening, closing and managing a sessionbetween end-user application processes (i.e. a semi-permanent dialogue). (e.g. X.225, ISO 8327)

5. 4 Transport Layer This is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet Protocol Suite and the Open Systems Interconnection(OSI) which provides services such as connection-oriented data stream support, reliability, flow control, and multiplexing. (e.g. SPX, TCP, UDP etc.) 5 Network Layer This is responsible for packet forwarding, since it knows the address of neighboring network nodes, and it also manages quality of service(QoS), recognizes and forwards local host domain messages to the Transport layer. (e.g. DDP, RIP, IPX etc.) 6 Data-Link Layer This provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the physical layer. (e.g. ATM, Econet, Ethernet etc.) 7 Physical Layer This defines the means of transmitting raw bitsrather than logical data packetsover a physical linkconnecting network nodes. (e.g. 1-Wire, Bluetooth, etc.)

6. P rotocol FTP may run in active or passive mode, which determines how the data connection is established. I n both cases, the client creates a TCP control connection from a random, usually an unprivileged, port N to the FTP server command port 21.

7. P rotocol ( C ontd) I n an A ctive FTP connection, the client opens a port and listens and the server actively connects to it. I n a P assive FTP connection, the server opens a port and listens (passively) and the client connects to it. Y ou must grant A uto FTP M anager A ccess to the I nternet and to choose the right type of FTP C onnection M ode.

8. H istory T he completion of FTP dates from 1 97 1 when a file transfer system (described in RFC1 4 1 ) between MIT machines ( M assachusetts I nstitute of T echnology) was developed. M any RFC have since made improvements/changes to the basic protocol, but the greatest innovation date from J uly 1 973. T he FTP protocol is currently defined by RFC 959 ( F ile T ransfer P rotocol ( FTP ) - S pecifications).

9. U sage O f FTP C lient connects to the FTP server U ser provides a login id and password to become authenticated U ser can explore the directories U ser can download files from and upload files to the server

10. M erits O f FTP A llows you to transfer multiple files as well as directories T he ability to resume a transfer if the connection is lost T he ability to add items to a “queue” to be uploaded/downloaded M any FTP clients have the ability to schedule transfers N o size limitation on single transfers (browsers only allow up to 2 GB) M any clients have scripting capabilities through command line F aster transfers then HTTP S upported on almost all hosts

11. D emerits O f FTP U sernames, passwords and files are sent in clear text F iltering active FTP connections is difficult on your local machine (passive is preferred) S ervers can be spoofed to send data to a random port on an unintended computer H ard to script jobs E asy for inexperienced users to wipe out work I nconsistency/inability to track what has been uploaded on the remote system