What is File Transfer Protocol : Working, Types & Its Applications

Transferring files is very easy between two systems but in some cases, some problems may occur while transferring. For instance, if we use two systems then they may have different file conventions, they represent data or text in different ways and they may include some different directory structures. To overcome this problem, file transfer protocol or FTP protocol is used by establishing two connections between hosts (client & server) over TCP/IP. One connection is mainly used to transfer data whereas another connection is used to control data. So, this article discusses an overview of a file transfer protocol or FTP.

What is FTP (File Transfer Protocol)?

The FTP or File transfer protocol is a typical internet protocol (IP) used to transfer the files between two hosts from client to server over TCP/IP (Transmission Control Protocol/Internet Protocol).In the TCP/IP, this protocol is considered an application layer protocol. By using FTP, files sharing from one system to another are possible, it encourages the remote computer’s usage and transfers the data more efficiently and reliably.

File Transfer Protocol
File Transfer Protocol

Types of File Transfer Protocol

The file transfer protocols are available in different types like HTTP, FTPS, HTTPS, SFTP, SCP, WebDAV, WebDAVS, TFTP, AS2, OFTP, and AFTP which are discussed below.


HTTP or Hypertext Transfer Protocol) is an extensively used protocol for transferring business files. This protocol is very simple to implement particularly for transferring files from person to server & person-to-person. HTTP is also liable to firewall issues but as compared to like FTP, this protocol is inherently insecure & not capable of securing data & meeting regulatory compliance. So this protocol is used where security is not a problem.


The secure version of FTP is FTPs or File Transfer Protocol Secure which is similar to HTTP has HTTPS. These protocols are protected by TLS (Transport Layer Security) and secure socket layer or SSL. FTPS allows businesses for connecting safely with their customers, trading partners & users. The files which are transmitted are simply exchanged and authenticated through FTPS-based applications like client certificates & server identities.


The secure version of HTTP is HTTPS or Hypertext transfer protocol secure and it is the main protocol utilized for transmitting data between a website & a web browser. This protocol is encrypted to enhance data transfer security. So this is mainly significant once users transfer sensitive data like bank account logging, health insurance provider, or E-mail service. The website which needs to log in must utilize HTTPS. The different Web browsers use HTTPS seriously but other browsers will flag all non-HTTPS-based websites as not safe.



The SSH File Transfer Protocol (SFTP) is a secure file transfer protocol that runs above the SSH which supports the complete security & authentication performance of SSH. This protocol has replaced legacy FTP as a file transfer protocol & is replacing FTP/S quickly. It gives all the functionality offered by these protocols more reliably & securely with a simple configuration.

SFTP guards from attacks, password sniffing, and reliability of the data by encryption & cryptographic hash functions, and verifies both the server & the user.


SCP is an older version of SSH File Transfer Protocol (SFTP) that works on SSH, thus it is available with similar safety features. But, if you are using a current SSH version, then you will have access already to both SFTP & SCP. When the functionality of SFTP is more than SCP then SFTP is recommended but the SCP is required only once you exchange files with a company that has only a legacy SSH server.


The Web Distributed Authoring and Versioning (WebDAV) runs on HTT and is designed mainly for collaboration activities. By using this protocol, users not only exchange different files but are also able to work together on a single file even if they are working from various locations. So this protocol is suitable for different organizations that require distributed authoring capabilities like research institutions & universities.


WebDAVS is the secure version of WebDAV where WebDAV works on HTTP and WebDAVS works over HTTPS. So, it exhibits similar WebDAV characteristics including the secure SSL features.


The TFTP or Trivial File Transfer Protocol is different as compared to other protocols because it is applicable for different network management tasks such as booting the network, configuration files backing up & OS installation over a network. This is a high-level protocol used for transmitting data servers to boot X-terminals, diskless workstations & routers with UDP (User Data Protocol).


The AS2 or Applicability Statement 2 is built for Electronic Data Interchange (EDI) transactions which are usually observed in the retail & manufacturing industries. Now this EDI is also utilized in healthcare. This protocol is an excellent choice if you work in these industries or need to perform EDI transactions.


The OFTP or Odette File Transfer Protocol is specially designed for EDI. This protocol is very common, especially in companies in Europe countries. Both AS2 & OFTP protocols are secure inherently & even support electronic delivery receipts to make them ideal for B2B transactions.


AFTP or Accelerated File Transfer Protocol developed by JSCAPE is designed to speed up file transfers over high-speed networks that are unable to fully utilize network throughput due to high latency and packet loss. Under these conditions, AFTP can accelerate file transfers up to 100 times faster than FTP and other file transfer protocols.

How Does File Transfer Protocol Works?

The mechanism of FTP is shown below. FTP is a typical network protocol that plays a key role in exchanging & manipulating files above a TCP/IP-based network like the Internet. This protocol is built over the client to server-based architecture. This architecture uses separate data & control connections between the client & server-based applications. This protocol is used for user-based password authentication otherwise by unknown user access.

File Transfer Protocol Working
File Transfer Protocol Working

The data transmitted from one system to another is very easy & also not complicated, but it can cause some issues occasionally. For instance, two systems may have different file conventions. So text & data may be signified differently within these two systems and the two systems’ directory structures may be dissimilar. This protocol overcomes these problems by making two connections between two hosts like client and server. One link is mainly used for transmitting data whereas the other is utilized for controlling data.

There are two kinds of FTP connections available control connection and data connection which are discussed below.

Control Connection

The control connection in FTP is mainly used to convey control data like user ID, secret code & commands for changing the remote directory commands for fetching & saving files, etc. This connection is simply established on port 21 of the server. This connection connects the control processes and it is kept open throughout the FTP interactive session.

The features of control connection include the following.

  • The control connection is helpful in transferring control signals between the client & server.
  • This kind of connection is simply utilized by the client & server’s control process which is known as PI or Protocol Interpreter.
  • The connection of TCP for control signal utilizes familiar FTP server port 21.
  • This connection will stay connected throughout the whole interactive session of FTP.
  • This type of connection uses simple communication rules. So we need to transmit simply a line of response & a line of command at a time

Data Connection

This protocol utilizes a data connection for transmitting the actual file & folder. This connection is also known as a separate connection. This connection connects the data transfer processes and it is created & closed for every file transmitted.

Once a user starts an FTP connection, then the control connection will be opened; when this connection is open, the data connection is opened & closed many times if the files of the server need to be transmitted.

The features of data connection include the following.

  • This connection is mainly used to transfer actual data.
  • This kind of connection is simply established between the DTP of the client & server.
  • For data connection, the Port 20 server port is used.
  • File transfer takes place on the data connection in the commands control sent above the control connection.
  • Throughout the transfer of file, the client should describe the kind of file to be transmitted, the data structure & the mode of transmission.


The characteristics of file transfer protocol include the following.

  • At the transport protocol, FTP simply uses TCP.
  • For control connection, this protocol uses port number 21.
  • This protocol is an out-of-band protocol because data &control information flow above different connections.
  • For data connection, this protocol uses port number 20
  • For control connection, this kind of protocol utilizes constant TCP connections.
  • For data connection, it uses non-persistent connections.
  • It is a connection-oriented protocol.


The features of file transfer protocol include the following.

Representation of Data

This protocol simply handles three kinds of data representations like ASCII, EBCDIC & 8-binary data

File Organization & Data Structures

This protocol supports both structured as well as unstructured files.

  • A structured type file includes a records list where every record is surrounded by End of Record. So data structure of such files is known as record structure.
  • An unstructured type file includes a series of bytes which is enl-marked through the End of the file. So data structure of such a file is known as file structure.

Transmission Modes

FTP uses three modes to transmit a file stream mode, block mode, and compressed mode.

  • Stream mode is called a default mode. In this mode, the file is simply transmitted like a constant stream of bytes toward TCP. So TCP is accountable for data chopping into correct size segments.
  • In Block mode, data is delivered in blocks from FTP – TCP where every block is preceded through three bytes header. The 1st byte is known as the block descriptor, and the 2nd & 3rd byte simply defines the block size in bytes.
  • In compressed mode, usually data is compressed if the transmitted file is very big.

Error Control

As TCP is utilized for data transfer no extra error recovery device is necessary.

Access Control

The protection of File access is done through the login procedure by entering login credentials.

Advantages and Disadvantages

The advantages of the file transfer protocol include the following.

  • By using this protocol, multiple files & directories are possible.
  • As compared to HTTP, FTP is very faster.
  • File transfer speed is very quick.
  • It is supported in nearly all hosts.
  • Most clients include a synchronizing utility.
  • FTP clients have the capacity to schedule a transfer.
  • No limitation size on single transfers.
  • Many clients have scripting capacities throughout a command line.
  • The capacity to include items to a line to be uploaded & downloaded.
  • FTP has a backup facility automatically.

The disadvantages of the file transfer protocol include the following.

  • Files and login details are sent within the clear text.
  • Encryption is not intrinsically offered otherwise enforced by each provider.
  • Simple for an inexpert user to destroy work.
  • TLS 1.2 is not supported above HTTPS always.
  • Active FTP connection filtering is very difficult on your local machine.
  • This protocol lacks safety
  • FTP can be susceptible to attack
  • Compliance is a problem.
  • It is very hard to check activity.

Applications of File Transfer Protocol

The file transfer protocol applications include the following.

  • The applications of file transfer protocol mainly involve several daily business operations across business-to-business & peer-to-peer data transfer:
  • FTP protocol is used in Organizations by allowing workers to split files across various locations as well as branch offices.
  • This protocol uses to securely transmit files through colleagues & outside business partners.
  • This kind of protocol is used by IT teams for transmitting data back to DR (disaster recovery) sites.
  • Webmaster teams utilize this protocol for transferring web pages, images & web application files to their web server.
  • This protocol is used by other medium and small businesses like architecture, construction & civil engineering, printing and transcription services, IT & business consulting, Media, marketing, and legal and financial services.

Thus, this is all about an overview of an FTP protocol – working, types, features, characteristics, and its applications. FTP is a TCP/IP-based IP that is mainly used to transmit files between two hosts. Here is a question for you, who invented FTP?