What Is FTP? The Basics of File Transfer Protocol

FTP makes transferring millions of digital files from servers to clients every day possible.

It’s the hero behind the scenes of many online activities we take for granted.

For example, in the business world, FTP is essential for managing large datasets, conducting backups, and sharing confidential documents between different locations. Small businesses, freelancers, and everyday internet users benefit and rely on FTP for various purposes.

What Is FTP?

File Transfer Protocol, commonly known as FTP, is a standard protocol for transferring files from one host to another over a TCP-based network, such as the Internet or an intranet.

It's a set of rules that define how files should be shared, uploaded, and downloaded, making it one of the oldest and most reliable methods for sharing data online.

FTP Protocol is built on a client–server model architecture using separate control and data connections between the client and the server.

The "server" is where the files are stored, and the "client" is the computer trying to access or upload those files.

When you need to transfer a file, the FTP client software on your computer communicates with the FTP server to perform the requested action, such as uploading or downloading a file. This communication is carried out through predefined FTP commands, making the process standardized and consistent.

FTP is particularly well-suited for transferring large or multiple files, offering reliable and fast transfers.

FTP is widely used in various applications today:

• Website Management: If you have a website, you've probably used FTP to upload files to your web server. This is how new web pages, images, and other types of content get added to websites.
• File Sharing: If you’re looking to share large data sets within a research institution or distribute software updates, FTP provides a reliable way to share files over a network.
• Data Backup: Many organizations use FTP for automated backups of critical data, ensuring that a copy exists offsite in case of system failures or other catastrophes.
• Content Management: For large, content-heavy platforms like e-commerce sites, news portals, or social media platforms, FTP is often used to manage and update the database efficiently.
• Remote Access: FTP allows professionals to access files remotely, making it easier to work from different locations.

Types of File Transfer Protocol

There are different types of FTP. Each has unique features, and choosing the right one will depend on your needs. Let's explore these types and their merits.

1. Basic FTP

The most straightforward version is known as "Basic FTP." This is the original protocol, allowing for the simple transfer of files between a client and a server.

Basic FTP lacks robust security features. For example, it sends data, including passwords, in plain text over the network, making it susceptible to eavesdropping attacks.

It relies on two separate Transmission Control Protocols (TCP) to function:

• Control Connection (Port 21)
• Data Connection (Port 20)

2. SFTP (SSH File Transfer Protocol)

SFTP stands for SSH File Transfer Protocol. SSH means Secure Shell.

Unlike basic FTP, SFTP offers enhanced security by encrypting commands and data. 

This prevents unauthorized access to the transferred data. It's commonly used for secure file transfers over networks and is an excellent choice when data security is a primary concern.

Let's say you're working for a company and need to transfer customer data from your work computer to the company server. Because this data is sensitive, you would use SFTP to ensure the customer information stays safe during the transfer.

3. FTPS (FTP Secure)

FTPS is an extension of basic FTP and adds support for Transport Layer Security (TLS) and its predecessor, Secure Sockets Layer (SSL).

These are cryptographic protocols that provide secure communication over a network. 

Like SFTP, FTPS also offers secure, encrypted data transfer. However, one key difference is that FTPS can work with multiple ports, which sometimes makes it more challenging to configure than SFTP.

Here's a quick comparison of the types:

• Basic FTP: Simple but lacks security features.
• SFTP: Secure, encrypted, and operates over a single port.
• FTPS: Secure and encrypted but may require multiple ports.

Expert Tip

You may also come across the term FTPES. This stands for "FTP with Explicit SSL" and is a subtype of FTPS.

Unlike FTPS, where encryption is implicit and automatically applied, FTPES allows you to convert a basic FTP connection to a secure one using SSL/TLS. 

In short, FTPES allows you the flexibility to switch between secure and insecure communication during a session, providing another layer of adaptability.

How Does FTP Work?

FTP operates on a client-server model, relies on specific commands for different operations, and can work in two different modes — Active and Passive. 

Let's dig into these aspects one by one.

First, when you're connected to an FTP server, you can:

• Upload a file
• Download a file
• Delete a file
• Rename a file
• View file information

Here is how the Client-Server model works.

There are usually two main players: the client and the server.

• Client: This is your computer, where you use an FTP program to ask for files to be transferred.
• Server: This is the computer where the files are stored. It waits for requests from clients like yours and then sends the files you asked for or accepts files you want to store.

The client (you) starts by connecting to the server. Once the connection is made, you can begin transferring files.

Finally, FTP can work in two ways: Active mode and Passive mode. These modes define how the data connection (port 20) is established between your computer (the client) and the server.

• Active Mode: The server connects to your computer in this mode. While this may sound good, it can sometimes be a problem if you're using a firewall that blocks incoming connections.
• Passive Mode: In passive mode, your computer makes all the connections to the server. This is generally more firewall-friendly and is often the default setting in many FTP programs.

Another fundamental thing to understand is that FTP uses TCP/IP to transfer files.

FTP Tutorial: A Step-by-Step Guide to How FTP Works

Let's follow John, who needs to upload some documents to his company's server. Let’s see how he uses FTP to transfer files.

• Step 1: John organizes the files he needs to upload into a folder on his computer. He also makes sure he has an FTP client software installed.

Commands Involved: None at this stage.

• Step 2: John opens his FTP client software and enters the server address, username, and password to connect to the company's FTP server.

Commands Involved: None from the user's end, but the FTP client uses the USER and PASS commands to log in.

• Step 3: The FTP client establishes two types of connections with the server: one for commands (port 21) and another for data (port 20).

Commands Involved: Implicitly AUTH (for secure connections)

• Step 4: John navigates to the folder on the server where he wants to upload his documents.

Commands Involved: CWD (Change Working Directory)

• Step 5: Before uploading, John checks to see if any files with similar names already exist in the target directory on the server.

Commands Involved: LIST

• Step 6: Sending a file via FTP: John selects the files on his computer to upload and initiates the transfer.

Commands Involved: PUT

• Step 7: The files are sent from John's computer to the server. This is done over the data connection.

Commands Involved: None, but the data connection becomes active here.

• Step 8: After the upload, John uses the LIST command again to confirm that his files are indeed in the target directory on the server.

Commands Involved: LIST

• Step 9: Once John verifies that the files have been uploaded successfully, he disconnects from the FTP server.

Commands Involved: QUIT

NOTE: If you're using graphical FTP software (like FileZilla or Cyberduck), all these commands are performed behind the scenes when you click buttons or menus. You don't have to worry about them.

However, if you're using command-line FTP, you'll need to type these commands yourself.

Either way, it's good to understand what these commands do, as it helps you better grasp how FTP works.

Types of FTP Servers

FTP servers are broadly categorized into three types based on their access mechanisms.

1. Private FTP

Private FTP servers require users to log in with a unique username and password to access the files. These servers are often used by businesses and organizations that need to transfer sensitive or confidential information securely.

• Security: High due to personalized access.
• Use-case: Secure business transactions and confidential data sharing.

2. Anonymous FTP

Anonymous FTP servers allow users to log in using a generic username and no password. These are often used for public file sharing.

• Security: Low, as anyone can access the server.
• Use-case: Public file distribution, open-source projects.

3. Public FTP

Public FTP is a server accessible to the general public but may still require users to log in with a username and password. They are commonly used to distribute software, public datasets, or other publicly accessible resources.

Unlike Private FTP, the access credentials for Public FTP servers are often shared openly or are easy to obtain.

These servers are used when you want to allow wider access to the data but still keep some level of control.

• Security: Moderate, as it balances public accessibility with optional credential requirements.
• Use-case: Academic resource sharing, community-driven projects.

Why Do You Need to Use FTP?

Why is FTP necessary when there are many ways to transfer files, such as email attachments or cloud storage services like Google Drive?

FTP has distinct advantages that make it an essential tool for specific tasks. Here's why you might need to use FTP:

• Efficiency in Transferring Data Over the Internet: Unlike email, which has size limits on attachments, or some cloud services that require uploading files before downloading, FTP allows for direct and quick transfer of files between computers.
• FTP Helps in Managing Large or Numerous Files: FTP is a more practical choice if you're dealing with large files—like video or software—or many files. Many FTP clients support batch uploads and downloads, allowing you to transfer multiple files or entire directories easily.
• Use Cases Like Website Maintenance or Backups: FTP is commonly used to maintain websites. Web developers often use it to upload new or updated files to web servers. It's also instrumental in creating backups. You can schedule FTP transfers to copy important files from a local system to a remote server at regular intervals, providing an automated backup solution.
• Opportunities for Automating Tasks: FTP can be automated to make repetitive tasks easier. For example, if you need to send a daily report to a remote server, you can set up an automated script that uses FTP to transfer the file at a specified time each day.

How to Use FTP?

Using FTP is straightforward.

Before setting up FTP access, you'll need a few things:

• Server Address: This is the FTP server's IP address or domain name you'll be connecting to.
• Username and Password: These are your login credentials for accessing the FTP server.
• FTP Client Software: You'll use this software to connect to the FTP server. Many options are available, some of which are free, like FileZilla, and others that you may need to purchase.

The next step is to initiate a connection:

• Open Your FTP Client: Launch the FTP client software on your computer.
• Enter Credentials: In the software interface, there should be fields to enter the server address, your username, and password.
• Connect: After entering your credentials, click the "Connect" button to establish a connection with the FTP server.

Once connected, you'll see your local files on one side of the interface and the server files on the other.

• To Upload: Navigate to the folder on your computer that contains the files you wish to upload. Drag these files into the directory on the server where you want them stored. Alternatively, some clients offer an "Upload" button or right-click option.
• To Download: Locate the files you wish to download on the server. Drag these into a directory on your computer, or use the "Download" button or right-click option in your FTP client.

Once you've finished transferring files, safely disconnect from the FTP server to ensure no data is lost and the connection is closed securely.

• Logout or Disconnect Button: Most FTP client software will have a "Logout" or "Disconnect" button. Clicking this will safely terminate your FTP session.
• Check for Confirmation: Some clients will send a confirmation message informing you that you've been disconnected successfully.

Remember always to disconnect safely to keep your data secure.

Top FTP Clients

1. FileZilla

FileZilla is a widely-used FTP client available for free on multiple Windows, macOS, and Linux.

With features like tabbed browsing, you can connect to multiple servers simultaneously. Plus, it lets you bookmark FTP servers for quicker access in the future and even offers a search function within the server.

2. Cyberduck

Cyberduck FTP client is available for both Mac and Windows. It supports FTP and SFTP for secure file transfers.

Cyberduck fits in smoothly with the Mac ecosystem. 

It uses Mac-specific features, such as storing login information in the keychain for easy access.

3. WinSCP

WinSCP is a specialized FTP client crafted for Windows users. It supports file transfer protocols such as SFTP, SSH, and WebDAV. 

You can use WinSCP to safely move files between your Windows computer and a remote computer running on a different operating system.

The WinSCP client has an intuitive Graphical User Interface (GUI), making it straightforward to copy files to and from a remote computer. And for those looking for advanced options, WinSCP offers automation capabilities via .NET assembly.

Conclusion

FTP allows for the efficient and secure movement of data. It's an essential tool that offers reliability, efficiency, and flexibility.

When it comes to choosing the right type of FTP and client, it all boils down to your specific needs. Do you prioritize speed, security, or perhaps a user-friendly interface?

Each FTP type—basic FTP, SFTP, or FTPS—has its own merits and drawbacks. Similarly, each client has unique features that might align more with your needs.

So, take your time to assess your requirements, consider the advantages and disadvantages of each option, and make an informed decision.