What Is Secure File Transfer? Understanding SSH, FTPS, and SFTP

Secure file transfer is essential in any hosting environment where sensitive data is frequently exchanged. Insecure transfers can lead to data breaches and loss of important information, posing significant risks to individuals and businesses.

To mitigate these risks, protocols like SFTP (SSH File Transfer Protocol) and FTPS (FTP Secure) have been developed specifically for secure transfers. SFTP relies on the SSH (Secure Shell) protocol to establish a secure connection, while FTPS uses SSL/TLS for encryption. Although SSH itself is not a transfer protocol but rather a protocol for secure network services, it plays a crucial role in ensuring the security of SFTP transactions.

Let’s explore the differences between FTP and SFTP (which uses SSH) and how they ensure your file transfers are secure. This guide will go through the most common protocols used for file transfer and explain why SFTP is preferred over FTPs for its enhanced security features.

What Is Secure File Transfer?

Secure file transfer refers to the process of transferring files from a computer to a remote host in a confidential way that ensures the security of the data. It typically involves encryption methods to protect the file contents from unauthorized access or tampering during transmission. Secure transfer protocols are designed to prevent data breaches, interception, and other security risks that might occur during transit.

Some commonly used secure transfer methods and protocols include:

1. SFTP (SSH File Transfer Protocol): Uses Secure Shell (SSH) encryption to safely transfer files.
2. FTPS (File Transfer Protocol Secure): Adds support for SSL/TLS encryption to the traditional FTP protocol.
3. HTTPS (Hypertext Transfer Protocol Secure): Encrypts transfers over the web using SSL/TLS.
4. AS2 (Applicability Statement 2): Used for secure business-to-business file transfers.

These protocols are commonly used in environments where sensitive information such as financial, personal, or business data needs to be protected while being shared between systems, often across the internet.

What Is FTP, and How Does It Work?

FTP (File Transfer Protocol) is a standard network transfer protocol used for transferring files between a client and a remote server. It’s a fundamental method for moving files from a local computer to a hosting account, making them accessible to the public. In this example, the client is your computer and the server is your hosting company’s web server.

When you use FTP, you start by connecting to a server using an FTP client. Once connected, you can upload files from your local computer to the server. These files are then accessible on your hosting account, allowing them to be shared or made available on a website.

However, FTP has inherent security vulnerabilities because it lacks encryption. This means data, including usernames and passwords, is transferred in plain text. Some of the key security risks include:

• Packet Sniffing: Hackers can intercept and read the data packets being transmitted, gaining access to sensitive information.
• Brute Force Attacks: Attackers can repeatedly attempt to guess your password, especially if it’s weak.
• Anonymous FTP Vulnerabilities: Allowing anonymous FTP can open up your server to unauthorized access.
• Port Stealing: Attackers can hijack your FTP session by taking control of the port used for the connection.

Despite its security weaknesses, FTP is still used in some scenarios due to its lower overhead than SFTP. For example, FTP’s lack of encryption means it can transfer files faster because there’s no added processing for encryption and decryption. However, for sensitive data transfers, the security benefits of SFTP generally outweigh the performance advantage of FTP.

FTP struggles to comply with modern security standards and regulations like the General Data Protection Regulation (GDPR) in Europe and the California Consumer Privacy Act (CCPA). These regulations require significant data protection measures, which FTP cannot provide.

Our general advice is that standard FTP is not worth the risk. If you do need to use FTP, only transfer non-sensitive data.

What Is FTPS, and How Does It Work?

FTPS (File Transfer Protocol Secure) is an extension of the standard File Transfer Protocol (FTP) that adds support for secure encryption using SSL (Secure Sockets Layer) or TLS (Transport Layer Security). It ensures that the file transfers between a client and a server are encrypted, protecting the data from being intercepted or tampered with during transit.

FTPS establishes a secure, encrypted connection between the client and the server using SSL/TLS. There are two modes of FTPS, explicit and implicit, which differ in how they initiate the secure connection.

In explicit FTPS, the client initiates a connection to the server on the standard FTP port (port 21) and then explicitly requests that the server upgrade the connection to an encrypted one using SSL/TLS. This mode allows the server to support both encrypted and unencrypted FTP sessions, making it more flexible.

In implicit FTPS, security is enforced from the very beginning. The client connects to the server on a different port (usually port 990), and the server automatically expects an encrypted connection using SSL/TLS. Implicit FTPS is less common than explicit FTPS and is considered outdated by some standards.

Benefits of FTPS:

• Encryption and Security: FTPS uses SSL/TLS to encrypt both control and data channels, protecting sensitive information such as login credentials and file contents.
• Authentication: FTPS supports various authentication methods, including username/password and SSL/TLS certificates, for both server and optional client authentication.
• Compatibility: FTPS maintains compatibility with the traditional FTP command set, making it easier for legacy systems to adopt secure file transfers without major changes.
• Compliance: FTPS is often used in environments where regulatory compliance (e.g., HIPAA, GDPR, PCI DSS) requires secure data transfer methods.

Challenges of FTPS:

• Complex Firewall Configuration: FTPS uses multiple ports—one for the control connection (port 21 or 990) and a range of ports for data connections. This can make it difficult to configure firewalls, as the server and client need to open and close ports dynamically for file transfers.
• Not Always Standardized: There is variability between how different FTPS servers and clients implement features like SSL/TLS encryption and client certificates, which can lead to compatibility issues.
• Support for Plain FTP: Some FTPS servers allow fallback to plain FTP (unencrypted), which could pose a security risk if not properly configured.

FTPS might be a good choice for organizations needing to meet regulatory requirements for secure data transfer, particularly when using legacy FTP systems. However, it may require more complex firewall configurations due to its use of multiple ports for control and data channels.

What Is SFTP, and How Does It Work?

SFTP (SSH File Transfer Protocol) is a secure transfer protocol that provides encryption and data integrity for transfers over a network. It is part of the SSH (Secure Shell) protocol suite and is primarily used to transfer files securely between a local and a remote system or between two remote systems.

Similar to FTP, SFTP operates by using SSH to establish a secure connection between a client and a server. Once this connection is established, all commands and data transfers are encrypted, ensuring confidentiality and data integrity during the transfer.

Benefits of SFTP Over FTP and FTPS:

• Security: SFTP provides strong encryption, ensuring that files are not exposed during transit. The use of SSH for both authentication and encryption adds an extra layer of protection.
• Data Integrity: SFTP ensures that the data sent between the client and server remains intact and unaltered during the transfer process.
• Firewall-Friendly: Unlike FTP or FTPS, SFTP only requires a single port (port 22), which simplifies firewall and network configuration.
• Comprehensive File Management: In addition to transferring files, SFTP supports other file management tasks, making it more versatile than simpler protocols like FTP.
• Wide Adoption: SFTP is widely supported by many operating systems and applications, making it a popular secure file transfer solution.

SFTP is a secure and efficient method for transferring and managing files across networks, commonly used in modern systems where security and data integrity are critical. We recommend SFTP in any situation but strongly encourage using it when transferring sensitive, personal, or confidential data.

The Role of SSH and SFTP in Secure File Transfer

Secure Shell is primarily a protocol for secure system administration and network services. It has the capability to tunnel other protocols, such as FTP, or to facilitate file transfers through SFTP or SCP (Secure Copy Protocol).

SSH provides secure, encrypted communication between two untrusted hosts over an insecure network. This encryption ensures that all data exchanged between the client and server is protected from interception and tampering. The encryption used by SSH covers both the data and the session, ensuring a high level of security and integrity.

SFTP, on the other hand, is a secure alternative to FTP that leverages SSH to provide data protection during transfers.

SFTP is not simply a newer version of FTP; it is a completely different protocol built on the SSH protocol.

It provides a high level of security by default, encrypting the session, the commands, and the data. This encryption protects against data interception and common network security risks, such as packet sniffing and brute force attacks, ensuring the integrity and confidentiality of the transferred files.

Over time, SFTP has replaced FTP as the preferred protocol for secure transfers. This shift is largely due to SFTP’s great security features, like strong encryption and versatile authentication methods, such as private keys or traditional usernames and passwords. On top of this, SFTP uses a single channel for both command and data transfer, which enhances its security by reducing the number of points vulnerable to attack.

For example, when transferring sensitive company data, using SFTP ensures that both the commands to transfer the files and the files themselves are encrypted, protecting against unauthorized access. This is particularly important for businesses that need to comply with strict data protection regulations.

A2 Hosting: Your hosting provider with FTP and SSH in every plan

A2 Hosting offers robust options for both SSH and FTP across all its hosting plans, addressing various security and performance needs.

• SSH Capabilities: A2 Hosting provides SSH access that supports command line and SSH File Transfer protocols. This ensures that all data transferred is encrypted and secure, giving you peace of mind when managing your server and transferring files.
• FTP Capabilities: With A2 Hosting, you get extensive FTP capabilities that support basic FTP and its more secure alternatives, FTPS and SFTP. While basic FTP is usually available for tasks that don’t require high security, like transferring non-sensitive files, we recommend using FTPS or SFTP whenever possible.

On top of that, our user-friendly interface makes managing FTP accounts simple. We support popular FTP clients like FileZilla, making it easy to transfer files to and from your server. Whether you’re a seasoned developer or new to website management, our tools are designed to help you do the job efficiently.

From secure transfer protocols to robust threat protection and virus scans, all of our Web Hosting Plans include security features to protect your data and ensure hassle-free data transfers.