File Transfer Protocol (FTP) Meaning and Definition

What is File Transfer Protocol (FTP)?

An FTP server is a program that transfers files from one computer to another using a set of rules. File transfer protocol (FTP) is used by businesses to send files between computers, and by websites for uploading and downloading files from their servers.

The FTP protocol involves opening two connections between the computers trying to communicate with each other. The first connection is used to send commands and replies between the two clients, while the second channel is for transferring data. During an FTP transmission, there are four commands used by the computers, servers, or proxy servers that are communicating. These are “send,” “get,” “change directory,” and “transfer.”

FTP transfers files in three different modes: block, stream, and compressed. With the stream mode, FTP can manage information in a string of data without defining any boundaries between them. In the block mode, data is divided into blocks, and in the compress mode, data is compressed using the Lempel-Ziv algorithm.

What is FTP Useful For?

FTP's ability to transfer large files is one of the main reasons why modern businesses and individuals use it. Most methods will suffice when sending a relatively small file, like a Word document, but FTP lets you send hundreds of gigabytes at once and still have a smooth transmission.

Sending larger amounts of data, in turn, enhances workflow. You can select multiple files and then send them all at the same time via FTP because it allows you to send multiple files at the same time. You may have to send them one by one without FTP services, when you could be doing something else. 

FTP can be used to send many documents at once, such as if you have to move a large collection of important documents from headquarters to a satellite office but have a meeting in five minutes. You can attend the meeting even if the transfer takes 15 minutes.

How Many Types of FTP Are There?

FTP can be used to accomplish a wide range of tasks, but there are three primary categories.

FTP Plain

Normal FTP without encryption is known as FTP Plain. Most web browsers support port 21, by default.

FTPS

FTP Secure or FTP secure sockets layer (SSL) refers to an FTP server that uses SSL encryption, which is slightly different from traditional FTP. The main difference is the security offered by FTPS, the first type of encrypted FTP.

FTPES

FTPES stands for File Transfer Protocol over explicit Transport Layer Security (TLS)/SSL because the "E" in the acronym means "explicit." FTP over explicit TLS/SSL begins the same way as regular FTP, but then special commands upgrade it into a TLS/SSL encrypted transmission. Many people prefer FTPES over FTPS because it is more compatible with firewalls.

How to Use FTP

FTP can be used in three ways:

• With a web browser, you can download files from FTP sites without using any special software or clients.
• A GUI FTP client is an application that allows users to connect and send files via FTP.
• FTP client capabilities are built into most operating systems as a command-line component.

FTP vs. SFTP

SFTP stands for Secure Shell File Transfer Protocol, while FTP stands for File Transfer Protocol. Using this, you can make secure file transfers with SSH, which gives you full access to shell accounts. Shell accounts reside on remote servers.

Unlike SFTP, FTP does not provide a secure channel for file transfers. A single channel is used for SFTP, while two channels are used for FTP. Each protocol uses different inbound connections as well. By default, FTP uses port 21, while SFTP uses port 22 for inbound communication.

The way data is transferred is also significantly different. SFTP transfers data via tunneling. Direct transfers, which are less secure, offer additional security over FTP.

FTP vs. HTTP

Although HTTP and FTP are application-layer protocols that let you send files between systems, there are some key differences between them. Because HTTP is a stateless protocol, it can support multiple sessions simultaneously. This means that it does not save the data used in a session so that it can be used in a subsequent session. 

In contrast, FTP is stateful, which means it collects information about the client and uses it in its next request. Since FTP performs this function, the number of simultaneous sessions is limited. Given the full bandwidth of a network, HTTP has the potential to be a much more efficient method of transmitting data.

Furthermore, with FTP, information must be authenticated by the client before it can be transmitted. With HTTP, this step is unnecessary. HTTP uses a well-known, common port, which makes it easy for firewalls to deal with. Firewalls can have trouble managing FTP in some cases.

TP vs. MFT

Compared to FTP, managed file transfer (MFT) is the new kid on the block. Despite being effective in many settings, FTP was not designed for today's complex threat landscape. FBI has issued an official warning about the possible pitfalls of using FTP, even if it is secured with SSL and SSH.

Managed file transfer includes features such as file management, compliance, and security. These measures must be in place, not only to make data transfer safer, but also to satisfy authorities that require secure data transfer, particularly for companies that handle sensitive data such as medical records. FTP can be eavesdropped or infected with a Trojan that targets financial institutions.

In spite of the fact that you could program the security and management features for safer FTP transmissions manually, MFT saves you the time and effort. In the example above, a hacker could intercept two people configuring dapps on Ethereum using the Mist Browser before they reach the FTP port. The hacker could then sell what was intercepted to a competitor who could use the information to create a similar app and release it sooner, thus gaining a strategic advantage.

Security Challenges of FTP

FTP does not provide a secure tunnel through which information can be transmitted. Encryption is not possible. Hackers who intercept FTP transmissions would not have to muddle through encryption in order to view or modify the data. If the service provider has a compromised system, data could be intercepted and exploited, even if you use FTP cloud storage.

Consequently, FTP data is a relatively slow-moving target for spoofing, sniffing, brute-force attacks, and other ways of gaining access to data. Using simple port scanning, a hacker could check an FTP transmission and try to exploit its vulnerabilities.

Clear-text passwords, which have not been encrypted, are one of the primary weaknesses of FTP. The password "Jerry1992" looks exactly like the password "Jerry1992." In more secure protocols, the password is disguised using an algorithm. FTP does not secure passwords like this, making them easier for bad actors to guess. Hence, "Jerry1992" may appear as "dj18387saksng8937d9d8d7s6a8d89."

How Fortinet Can Help

Demilitarized zones (DMZ) often house FTP servers. An organization's local-area network (LAN) is protected from potentially dangerous traffic by a DMZ network. Using FortiGate, Fortinet's next-generation firewall (NGFW), is one of the best ways to protect FTP transmissions. FortiGate offers different ways to protect FTP-based communications.

A single NGFW could be used. An NGFW in place can control and monitor traffic, and only approved data packets are allowed into the DMZ.

A dual firewall offers more security than a single NGFW solution. Using a dual firewall setup, both firewalls are deployed on either side of the DMZ. NGFWs monitor and control traffic coming into the network from outside the DMZ. The second firewall protects your organization's internal network from the DMZ. 

In order to access your internal network, an attacker would have to compromise two NGFWs. With FortiGate, you can restrict access to a web server protected by the DMZ to specific users. With this solution, you can choose who has access to sensitive information. Sensitive data, even that sent via FTP, is protected by an enhanced level of security that is otherwise impossible.

Are you concerned about cyber-attacks, unwanted access, and data loss on your network, network traffic, and network-connected assets? We can help.