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What is File Transfer Protocol (FTP)?

Andrea Taktak, Raymond Blockmon
  • Author
    Andrea Taktak

    Mrs. Taktak is in her 21st year of teaching high school science courses. She has designed curriculum and lessons for Forensic Science and Sports Medicine, and has taught Honors Biology, Anatomy and Physiology, Physical Science, and Environmental Science. Mrs. Taktak is a Master Teacher with a Teacher Leader Endorsement and has a Masters Degree in Education from Graceland University as well as a Bachelors of Science degree from Northern Kentucky University. She also most recently earned her Ohio Certified Volunteer Naturalist certificate while studying and volunteering at the Cincinnati Nature Center.

  • Instructor
    Raymond Blockmon

    Raymond has earned a bachelor's degree in computer information systems and a master's degree in organizational leadership.

What is FTP and its history? Learn the types and uses of FTP . What is the need of, and the working of FTP? Learn about FTP Clients and FTP Security. Updated: 12/31/2021

What is File Transfer Protocol?

File Transfer Protocol (FTP) - A protocol is a defined set of rules, and in the case of FTP, it is a specific set of rules used by a computer system to transfer files across the internet. FTP is different from traditional websites (Hypertext Transfer Protocol or HTTP). HTTP is designed to deliver text and images to be formatted in a layout for display via an Internet Browser such as Chrome, Safari, or one of many other browsers.

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  • 0:00 File Transfer Protocol Defined
  • 2:23 Significance of Port 20 and 21
  • 3:15 TCP and UDP
  • 4:21 Security
  • 5:04 Lesson Summary
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History, Types, Categories of FTP

The original idea for File Transfer Protocol (FTP) was created by Abhay Bhushan on April 16, 1971. This original concept was designed on the Network Control Protocol (NCP). Later FTP was modified to use the TCP/IP protocol. This would allow it to be more flexible and be integrated for use with what would soon become the Internet as we know it.

In contrast to a traditional website where a domain is preceded with the www prefix, FTP uses the same domain and will have the FTP prefix. For example, a company that owns domain.com will host its web server at www.domain.com and its FTP server at ftp.domain.com. This prefix allows the company to direct traffic to specific ports, which also may, but don't have to, route traffic to separate servers.

There are several types of FTP connections:

  • Anonymous FTP- this is the least secure type of FTP. Also known as simple FTP or abbreviated SFTP. There is no requirement for a user to log in, nor is there any type of encryption.
  • Password protected FTP - add a layer of security to traditional FTP in that there is a requirement of a username and password in order to access the server. The files are still transferred unencrypted. Username and password are transmitted in plain text.
  • Secure FTP- abbreviated as S-FTP, has a higher level of security by forcing transport layer security (TLS) once the connection is established. This TLS layer will encrypt the username and password.
  • FTP with SSL/TLS - one of the most secure types of FTP by forcing explicit TLS and moving the connection from port 21 to an encrypted connection. All data transmitted is encrypted with AES encryption.

What is FTP Used For?

FTP is typically used to transfer larger files from one computer to another. Typically these files are not sensitive in nature. The reason FTP is typically only used in larger files is that the time needed to create the FTP connection between the client and server can negate the time saving of the protocol when transferring smaller files.

FTP Applications:

  • Transferring a video that needs to be saved for later viewing
  • Installation files for programs or operating system
  • Transferring a folder(s) containing a large number of files or images

FTP Port Number

A port is similar to a door on a building. Each door has a specific purpose. The main entrance of a building may be for customers, while the rear door is used for deliveries. Computer systems operate on a very similar concept, but these doors are called ports. FTP used two different ports in order to initiate and transfer a file. The first port is port 21. This port is used for the commands that are sent between the client and the server, and the most common port users are familiar with FTP. The second port is port 20. This is the port that the data is actually sent and received from. Once a user establishes their credentials with the server via port 21, the requested files are then sent out of port 20 from the sender to the receiver.

How FTP Works

In an Active FTP connection and transmission, the Client will initiate the connection on a port it determines, in this case, port 1. The server receives the connection request on port 21. The server will then transmit the data out of its port 20 to be received by the client on a port it determines, in this case, port 2. In an Active Connection, the client determines the ports to be used.


Notice the difference in the port numbers on the client side versus the server side. The FTP Client is communication on Port 1 whereas the FTP server is communicating on Port 21, and the files will be transferred from the FTP Server on Port 20 but will be received on the FTP client on Port 2

Active FTP Connection

In a Passive FTP connection, the client will make a connection request on the port specified by the server, in this case, port 21. The data will then be transmitted via the port determined by the server, in this case, port 20. In a Passive Connection, the server determines the ports to be used.


Notice that the port numbers for the connection and the transmission are the same on the client and the server. Both the FTP Server and the FTP Client are communicating on Port 21 and the files will be transferred on Port 20

Passive FTP Transmission

Differences between FTP, HTTP, and MFT

In its simplest form, File Transfer Protocol, FTP, is an unsecured connection between the client and a server. The FTP transmission can occur in several different forms, each having a specific advantage. There are two different types of transmission types, active and passive. There are different types of FTP which include Standard FTP, Password Protected FTP, Secure FTP, and FTP with SSL.

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Frequently Asked Questions

What is FTP and how it works?

File Transport Protocol or FTP is a client-initiated transfer where the client can receive a file or can send a file to the server. The specific type of transmission, as well as the level of security, is determined by the server.

What is FTP and its types?

There are many types of FTP types:

Active

Passive

Simple FTP - SFTP

Password Protected FTP

Secure FTP - SFTP

FTP over SSL

Where is FTP used?

File Transport Protocol or FTP is typically used in business environments to send or receive larger files across a local network or the internet.

What is File Transfer Protocol used for?

File Transport Protocol or FTP is used to transfer larger files from one computer system to another across a local network or the Internet.

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