What Is FTP? Everything You Should Know About File Transfer Protocol

Before I became a web developer, I really had no idea how a website went from code on your computer to a fully styled site on someone else’s screen halfway around the world. Surely it wasn’t magic, but I figured there must be some sort of sorcery enabling this unbelievable trick.

In my Intro to Web Design class, I learned that code on your computer gets uploaded to a server through a process called File Transfer Protocol.

FTP is a file transfer protocol used to transfer files between a client and a server on a computer network.

You see, FTP works like a tunnel that allows you to send and receive files securely over the internet. Web developers, IT professionals, and just about anyone needing to move large amounts of data use FTP to simplify the process. Aside from streamlining data transfer processes, FTP promotes data security, integrity, and privacy.

In this article, we’ll discuss everything you need to know about FTP, from the basics to the advanced features. Let the magic show begin!

FTP is a short form for File Transfer Protocol. This refers to a standard network protocol for transferring files between a client and a server over a computer network.

The protocol operates on a client-server relationship. This means the client initiates a connection to the server to upload or download files.

FTP operates on two separate channels. The first channel controls the conversation between the client and the server.

The second channel, conversely, handles data transfer processes. By separating these channels, FTP can function without interruption.

You can think of these two channels as a set of headphones — they comprise a built-in speaker and microphone. That’s how you can communicate and receive audio communication using the same device.

Imagine a situation where these two communication channels share the same line. That would be chaotic. You’d have difficulty listening to the person on the other side of the line or even conveying your message to them.

The History of FTP

FTP isn’t new to the game. This technology has been around since the early days of the internet. Abhay Bhushan first proposed it on April 16, 1971, and has evolved to accommodate advances in technology and security.

Initially, FTP relied on plaintext authentication, which was very risky. Here’s why:

With plain text authentication, your username and password are sent over the network in plain text. It’s similar to sending a postcard with your login details written for anyone to see.

There’s no encryption to protect this sensitive information. So anyone with access to that postcard will also see your login credentials.

Secure versions such as FTP Secure (FTPS) and SSH File Transfer Protocol (SFTP) were developed to address this risk. The goal was to introduce encryption to protect data during transfer.

How FTP Works

The FTP process is pretty straightforward. As the client, you connect to an FTP server using your login credentials. Once authenticated, you can upload, download, or manage files on the server.

As we mentioned, there are two types of connections: the command and data channels. The command channel handles the control information, such as:

• logging in
• changing directories
• issuing commands to transfer files

On the other hand, the data channel only handles the actual transfer of file data.

It’s also important to understand the role of FTP clients in this file transfer process.

FTP clients are software applications that interact with FTP servers. Some popular FTP clients include FileZilla, Cyberduck, and WinSCP.

There must be FTP server software, such as vsftpd or ProFTPD, on the server’s side. The role of this software is to listen for incoming connections and manage file storage and access permissions.

FTP in the OSI Model

Let’s briefly look at the Open Systems Interconnection (OSI) model to understand further how FTP works. This conceptual framework is used to understand and implement standardized network communication protocols in seven unique layers.

Each layer has a specific role and interacts with the layers directly above and below it. Thanks to OSI, network professionals can understand and troubleshoot complex networks by breaking down the communication process into manageable parts.

FTP fits within the application layer. This is the topmost layer of the model and is responsible for providing network services directly to end-users and applications.

FTP then uses the features and functionalities of the lower layers to establish a connection and transfer data between the client and server.

It’s also worth noting that FTP is not a lone ranger; it relies on other protocols to function correctly. For instance, it uses the Transmission Control Protocol (TCP) at the transport layer to establish and maintain a reliable connection between the client and server.

FTP may interact with the Domain Name System (DNS) at the network layer to resolve server domain names into IP addresses. That explains why most FTP clients will require an IP address to authenticate the connection you’re trying to establish.

We’ll examine its components and architecture to understand how FTP operates. We’ve already seen that FTP relies on a structured system of clients and servers.

Each system plays a vital role in making the file transfer process successful. Let’s break down the key components and their functions.

FTP Clients

An FTP client is usually software used to connect to an FTP server. Once the connection has been established and authenticated, you can upload, download, and manage files.

The software is the user interface for accessing the server’s file system.

Examples of FTP clients include:

• FileZilla
• Cyberduck
• WinSCP

FTP clients also have different features, such as drag-and-drop file transfers, synchronization (between the client and the server), and secure connections through FTPS or SFTP.

Thanks to this software, you can transfer files and manage permissions even if you’re not tech-savvy. Most of the steps involved are pretty easy to follow.

FTP Servers

An FTP server is the environment that listens for incoming connection requests from FTP clients. Upon establishing and authenticating the connection, it handles the transfer and storage of data.

Some of the most widely used FTP server software include:

• vsftpd
• ProFTPD
• FileZilla Server

They all help manage user access, set directory permissions, and ensure file transfers are conducted securely and efficiently.

FTP Commands

As the name implies, FTP commands are the instructions sent from the client to the server to perform various tasks.

Common FTP commands include:

• GET: Downloads (or rather “gets”) a file from the server to the client’s computer. Think of it as fetching a file from a remote location and saving it locally.
• PUT: Uploads a file from the client’s machine to the server. We use this command to send files to the server for storage or sharing.
• LIST: This function lists all files and directories on the server. It is handy when you want to see what files are available on the server before deciding which ones to download or upload.
• DELETE: This command removes a file from the server. It helps free up storage space and organize the server’s file system.

You’ve probably noticed that these commands are named in such a way that they make sense in the English language. That also makes it easier for users to understand what that command does.

As we’ve discussed so far, FTP is a file transfer protocol. But that’s more of a universal definition of this process.

FTP comes in several types, each designed to cater to a unique set of needs, be it security, network configurations, or anything along those lines.

Active vs. Passive FTP

Active and passive FTP dictate how the client and server establish a connection. The primary difference lies in how the data connection is initiated and managed.

Active FTP

In active FTP, the client opens a random port above 1023 and sends the server its IP address and port number. The server then initiates a connection back to the client using this port.

This option isn’t the best if you’re on a network with strict firewall rules because the client must accept incoming connections from the server.

The only times using active FTP makes sense is when you’re on a network with permissive firewall settings, or you trust the server to initiate connections.

Passive FTP

In passive FTP, the client initiates both the command and data connections.

Here’s how this process works.

First, the client sends the initial request. Then, the server opens a random port and informs the client of this port number. The client then opens a connection to this port for data transfer.

It’s similar to knocking on a door, and you’re granted access immediately.

Passive FTP is preferred in environments with strict firewall rules, as it avoids the need for the client to accept incoming connections. This mode is handy for clients behind Network Address Translation (NAT) devices or firewalls that block incoming connections.

Secure FTP Variants

Security is always a major concern when transferring files. We use secure FTP variants to protect sensitive data during transfer.

These variants, such as FTPS and SFTP, add encryption to the FTP process to ensure safe data transmission, including login credentials.

To paint a visual picture of how secure FTP variants operate, you’ve probably watched how VIPs, such as presidents, travel from one place to another.

You’ll find the VIP’s vehicle surrounded by armed security personnel to prevent an attack. In this case, the security personnel are the extra layer of encryption we’re referring to, and the FTP is the VIP.

FTPS (FTP Secure)

FTPS makes standard FTP even more secure. SSL/TLS encryption is added to the data transfer process to achieve heightened security.

This means the command and data channels we discussed are encrypted. To be more specific, it protects your login credentials and files from being intercepted.

FTPS is essential in environments where compliance with security standards is required. The financial and healthcare sectors are good examples.

SFTP (SSH File Transfer Protocol)

SFTP, unlike FTPS, is not an extension of FTP. These two (SFTP and FTPS) get many people slightly mixed up.

SFTP operates over the Secure Shell (SSH) protocol and offers a secure channel for file transfer.

Because of this, it’s widely used in secure environments that require robust authentication and data encryption, such as corporate networks.

Below, I’ll share a step-by-step guide on setting up and using FTP on Windows and Linux. Let’s get started.

Setting Up an FTP Server

First, you must install and configure server software to manage user access and handle file transfers. The server will listen for incoming FTP connections and facilitate file uploads and downloads.

Remember, we learned that the right server software will depend on your operating system, among other things.

Step-by-Step Guide for Windows

Assuming you’re on Windows, once you’ve set up and configured the server software, here’s what to do next:

1. Install an FTP server application such as FileZilla Server or Microsoft IIS (Internet Information Services).
2. Open the FTP server application and configure the server settings, select the port (default is 21), set up user accounts, and define directory access permissions.
3. Create user accounts and set their passwords.
4. Ensure that your firewall allows FTP traffic by opening port 21 and any additional ports required for passive mode.
5. Use an FTP client to connect to your server using the credentials you set up to ensure everything is working correctly.

FileZilla and WinSCP are among the most popular Windows FTP clients. I find FileZilla much easier to use, but you’re free to pick whatever works best for you.

Step-by-Step Guide for Linux

If your computer runs on Linux, follow these steps:

1. Use a package manager to install an FTP server application for Linux.
2. Edit the configuration file (e.g., “/etc/vsftpd.conf” for vsftpd) to set the necessary parameters, such as anonymous access, local user access, and directory permissions.
3. Use system commands to create new user accounts and set their passwords. Assign them to specific directories if needed.
4. Adjust your firewall rules to allow FTP traffic. On Ubuntu, you can use “sudo ufw allow 21/tcp” for FTP and additional commands for passive mode ports.
5. Launch the FTP service using “sudo service vsftpd start” and test the connection using an FTP client to ensure the setup is correct.

ProFTPD and vsftpd are among the most preferred FTP server software for Linux users. However, you can also use FileZilla, which is cross-platform.

Using an FTP Client

Assuming the server part is taken care of, you’ll need to set up the client next. You can use FTP clients, including FileZilla, Cyberduck, and WinSCP.

How to Connect to an FTP Server

Here’s how to connect your FTP client to the server.

1. Launch the FTP client application.
2. Input the FTP server’s address, port (usually 21), username, and password into the designated fields. Use the same login credentials you used when setting up the server.
3. Select the connection type (FTP, FTPS, SFTP) based on the server’s configuration.
4. Click the Connect button to establish a connection with the FTP server.

How to Transfer Files Using an FTP Client

Now that we’ve set up both sides and established a connection, it’s time to transfer files.

1. Navigate to the local directory on your computer and the remote directory on the server where you want to transfer files.
2. Select the files you want to transfer.
3. Start the file transfer by dragging the files to the desired location or using the upload/download buttons in the client interface.
4. Monitor the transfer progress bar to ensure all files are successfully uploaded or downloaded.

Standard FTP is not secure, so you must implement security measures during the transfer process. In this section, we’ll focus on potential security issues and how to solve them.

Common Issues

Earlier, we learned that one of the primary security concerns with standard FTP is transmitting data in plain text. This means that if a malicious party intercepts the transfer, they will have complete access to the data.

Standard FTP also lacks robust authentication mechanisms, which increases the risk of unauthorized access and data breaches.

Securing FTP Transactions

Using variants such as FTPS and SFTP can help fix FTP’s security issues. FTPS encrypts data, while SFTP operates over the Secure Shell (SSH) protocol to provide a safe tunnel for the traveling data.

To fix the issue of standard FTP not having robust authentication mechanisms, you’ll need to implement multifactor authentication (MFA).

Multifactor authentication requires users to provide at least two types of authentication. On the other hand, two-factor authentication, or 2FA, only requires two types of authentication.

This adds an extra layer of security by requiring additional verification steps beyond just a username and password. You’ve probably seen this verification method in play when logging into your online banking system, especially on a new device.

They’ll send a verification code via email or text message. Only when you confirm the code will you be granted access to the system.

Best Practices for Security

It’s one thing to know how to secure the file transfer process and another to understand the best practices for such a process to be successful. Here’s a summary of the best practices for security.

• Regularly updating your FTP software: This practice can help patch loopholes and improve security features with the latest updates.
• Monitoring and logging FTP activity: By keeping a record of FTP activity, you’ll be highly unlikely to be caught unprepared in the event of malicious activity.
• Limiting user access and permissions: You shouldn’t open the doors to anyone who knocks at your server’s door; some may abuse their privileges. Instead, ensure that whoever you add to the system only has access to the files and directories necessary for their roles.

Note that the specific FTP security measures needed to keep your transactions safe will depend on your unique situation. For example, in some scenarios, you may need to set up IP whitelisting and conduct vulnerability assessments periodically.

So far, we’ve talked about the what and how of FTP. Let’s talk about who should use it and when.

FTP is not the only way to transfer files from point A to point B. Here are some alternatives:

HTTP/HTTPS

HTTP and HTTPS are protocols designed to serve web pages and files over the internet. The main difference is that HTTPS provides encryption, ensuring secure data transfer.

Another important characteristic of HTTP/HTTPS is that it transfers files that must be accessed via web browsers. For instance, you’re reading this article because it traveled from our server to your device via HTTPS.

Cloud Storage Services

Google Drive, Dropbox, and OneDrive have many things in common. Both are cloud storage providers. They also facilitate file sharing, offer collaboration tools, and allow automatic device syncing.

However, the critical difference is that FTP offers more control and customization for server setups. At the same time, cloud services provide convenience and accessibility, which is particularly great for users with limited or no technical background.

You don’t need to be a tech geek to know how to use Google Drive, but you need to know a thing or two about technology to use FTP.

Other File Transfer Protocols

Some popular alternatives to FTP include:

• SCP (Secure Copy Protocol): Transfers files between local and remote hosts.
• Rsync: Synchronizes files and directories between different systems.
• WebDAV (Web Distributed Authoring and Versioning): Extends HTTP and allows users to edit and manage files on remote web servers collaboratively.

Note that the three protocols mentioned above are not in any way meant to replace FTP. Each one of them serves a unique purpose.

That wraps up everything you should know about this file transfer protocol. The key pointers here are that FTP makes transferring files — especially larger ones — much easier and faster.

However, standard FTP is not secure, so don’t use it to transfer sensitive data without protection.

The security aspect only kicks in when you use protocols such as FTPS. You should keep that in mind before transferring files from the client to a server.

All said and done, FTP may not be bullet-train fast, but it makes file transfer easier.