File transfer protocol (FTP) allows you to transfer, download, and upload files between computer systems using the internet. FTP makes use of an internet connection, with FTP transfers forming the backbone of the internet.
Website owners use an FTP client to upload and download the files required for data transfers. Most websites have FTP built in, though there are several FTP services website owners can use if they don’t have access.
This article delves into what FTP is, how it’s used, how it works, and the various types of FTP.
What Is FTP?
File transfer protocol (FTP) is a network protocol. It facilitates data transfer between computers using Transmission Control Protocol/Internet Protocol (TCP/IP). The FTP protocol is one of several within TCP/IP, and it operates as an application layer protocol.
FTP makes use of hosts to transfer files. These hosts include the remote host, which is often a server, and the local host, which is typically the end user’s computer. Both hosts must connect to a network and have proper configuration to allow file transfers. FTP servers are required to offer any FTP services, with FTP software facilitating the data connection.
How Is FTP Used?
FTP can be used for significant file transfers across internet protocol (IP) networks. Other methods exist for these transfers, such as hypertext transfer protocol (HTTP) and email. However, those options lack precision and control. Furthermore, FTP enables users to share files across an encrypted connection.
FTP is most commonly used to transfer files and data from one system to another. Use cases include the following.
Replication
Data is duplicated from one system to another via an FTP connection. This duplication provides high resiliency and ensures data availability.
Backup
People can use FTP to transfer files from one location to another. In the case of backing up, the user sends files from their system to a secured server that runs FTP services.
Access and Data Loading
The advent of cloud computing let users could data onto remote systems, often via web browsers. Transferring data via FTP offers access to cloud services and shared web hosting.
How Does FTP Work?
As a client-server protocol, FTP uses two communication channels to form a connection between the user and server:
- Control connection
- Data connection
Control Connection
An FTP client sends a connection request to a server port, typically server port number 21. Upon request acceptance, a control connection is formed.
The FTP client uses this data channel to send and receive commands and responses. The user may have to log onto an FTP server with a username and password to form this connection. However, anonymous FTP servers allow individuals to make content available without the need for a username and password.
A control connection uses simple communication rules. Think of it as a command channel. The server transmits a response and command line at the same time. The user’s system responds in kind.
Data Connection
Transferring files and folders requires a different form of data transfer. This is where a data connection comes into play. The FTP server sets up the data connection with the FTP client in either active mode or passive mode.
In active mode, the user connects to port 21 of the FTP server using a random port on the FTP client. The server receives a port command, which tells it which client port it should use. Upon establishing a connection, the FTP client can download files from the server.
Some FTP clients use firewalls, such as the Microsoft Windows Firewall, which makes active mode impossible to use. In these cases, they can use passive mode.
Again, the user connects from a random port on the FTP client to port 21 of the server. However, it sends the PASV command to establish the connection. Upon receiving access, the FTP server can transfer multiple files to the FTP client.
Types of File Transfer Protocol
There have been several revisions to this protocol throughout the history of FTP. These revisions led to the creation of several types of file transfer protocol (FTP).
Anonymous FTP
Anonymous FTP is the simplest form of the protocol. It allows file transfers without requiring any verification and without using encryption.
FTP clients may use anonymous FTP when distributing materials that carry no restrictions. However, it isn’t useful for any file transfer involving sensitive information.
FTP Secure (FTPS)
If security is a priority, FTPS is the solution. Also referred to as FTP Secure Sockets Layer (FTP-SSL), this protocol creates Transport Layer Security (TLS) upon establishing an FTP connection.
FTPS uses server identities and client certificates to verify file transfers. It’s useful for businesses that wish to transfer files to users, customers, and trading partners.
Password-Protected FTP
As the name implies, a password-protected FTP uses passwords to secure connections. However, the use of a password doesn’t guarantee the use of encryption, which is where file encryption software can help.
Beyond the password, this is the same as basic FTP sessions. Many FTP clients use password-protected FTP to enable multiple file transfers to authorized users.
Secure FTP (SFTP)
SFTP is an interesting case because it’s not technically an FTP protocol. Rather, it’s part of the Secure Shell (SSH) protocol, meaning it uses port number 22 instead of 21.
Even so, it functions similarly to FTP. System administrators often use SFTP to access applications and systems remotely. Furthermore, the SSH protocol enables more secure file transfer.
FTP Over Explicit SSL/TLS (FTPES)
FTPES creates an encrypted connection that lets users transfer files safely over the internet.
It uses port 21 and allows file and web-sharing services to transfer files across a secure data channel.
Trivial File Transfer Protocol (TFTP)
Using FTP may not be suitable for some tasks. TFTP provides a high-level protocol for these situations.
For example, TFTP enables various network management tasks:
- Booting a network
- Operating system installation over a network
- Backing up a configuration file
TFTP allows data servers to transmit the files required for diskless workstations and routers that use the User Data Protocol.
The Pros and Cons of Using FTP
There are many benefits of using FTP, making it the file transfer standard for the modern internet.
These benefits include:
- The ability to resume transfers if a connection gets broken
- Transferring multiple folders and files over an external or internal network
- Scheduling transfers via FTP clients
- Faster data transfer than HTTP
- No limitations on the sizes of files you can transfer
- The ability to add files to a queue via an FTP client
Unfortunately, there is one major downside to using FTP for transferring files. Unless you’re using FTPES, the data you transmit is vulnerable. FTP doesn’t automatically encrypt data, such as usernames and passwords.
This lack of encryption can create problems when sending files to customers. Hackers can capture data packets, which are transmitted in cleartext. Such attacks could give the hacker access to sensitive information, which they could use to access accounts illicitly.
Other disadvantages include:
- It’s easy for an inexperienced user to destroy work using FTP
- Compliance can be a problem when using FTP because it’s difficult to check activity
FTP Is the Backbone of the Modern Internet
Now you have the answer to what is FTP question, you can see that it’s essential to modern-day internet usage.
FTP makes it easy to download and upload files across an internet connection. It also powers data transfer via the cloud, making it essential for many Software as a Service (SaaS) applications.
For these reasons, most web browsers come with pre-installed FTP clients. However, many users opt for third-party FTP clients or IDEs because they often provide additional features.
Simply put, you’re likely using FTP whether you realize it or not. Any time you download data from a web page, FTP likely plays a role. Furthermore, its faster speeds and lack of restrictions make it preferable to other protocols, such as HTTP and Network Time Protocol (NTP).
