FTPS vs SFTP: The Background

Both FTP and SFTP are widely used file transfer protocols today. The FTP protocol was invented in the 1970s but is still an essential means of data distribution and transfer for many businesses and organizations. SFTP was spawned by the well-known secure shell (SSH) protocol as its native file transfer framework. We now offer a deeper look at their backgrounds and underlying technologies and then make a conclusion on which is more secure. 

What is File Transfer Protocol (FTP)? ​

FTP, also known as File Transfer Protocol, can be defined as a network protocol for transferring files between two computer systems. The files are transferred over TCP/IP connections. FTP servers act as centralized hubs where important data can be stored and accessed by different users within an organization, enabling efficient data management through FTP client tools. The File Transfer Protocol (FTP) was a product of the early internet (starting with RFC 114 in 1971), designed for an era where network security was not a primary concern. As the need for privacy grew, FTP was "upgraded" via the SSL/TLS layers to become FTPS, maintaining its original command structure while wrapping the data in a secure tunnel.

Types of Secure FTP ​

Implicit Secure FTP (FTPS) ​

Implicit FTPS, by default, provides service on port 990. SSL/TLS handshake takes place right upon connection is established, i.e., the secure connection begins immediately when the client connects to the server. All commands, authentication details, and transferred files are encrypted between the client and server.

FTP Over Explicit SSL/TLS (FTPES) ​

Explicit FTPS starts as a standard FTP connection before upgrading to a secure encrypted SSL/TLS connection using the AUTH TLS and PROT commands.

This method typically operates over the standard FTP port 21 and is more commonly used in modern enterprise environments.

FTPS is often preferred by organizations that already use traditional FTP infrastructure and want to improve security without completely redesigning their systems.

What is SFTP? ​

SFTP, also known as SSH (Secure Shell) File Transfer Protocol, is packet-based protocol designed to handle file transfer and management over the network. The protocol doesn't have built-in security per se; rather, it depends on an underlying secure socket layer to function, usually SSH. (Yes, the same group of people invented them both.)

On a Unix or Linux system, SFTP is typically a subsystem that exchanges raw file data and instructions with the parent SSH process. The latter is responsible for encrypting and protecting the data when it goes on the wire.

The Secure Copy Protocol (SCP) is an alternative file transfer protocol that runs also on top of the SSH layer. As the name implies, it was designed to replace the regular Unix cp command to enable file copying over the network in a secure way.

The primary functions of SCP are to build a connection between two systems, copy files from one system, and then close the link once the files have been copied into the other. Compared to SFTP, SCP is much simpler and doesn't allow file manipulation features like delete, rename, move, directory listing, etc. 

SFTP encrypts all commands, authentication credentials, and transferred data using SSH encryption. SSH listens on port 22 by default (assigned by IANA), and SFTP uses the same connection.

Because SFTP uses a single encrypted connection, it simplifies firewall configuration and improves security management.

SFTP is commonly used in enterprise automation, DevOps workflows, cloud environments, Linux systems, and secure managed file transfer solutions.

SFTP vs FTPS: Key Differences​

Plain FTP should be avoided to transfer unprotected plaintext data over the network. Now let's look at some of the key differences between secure FTP (FTPS) and Secure Shell (SSH) File Transfer Protocol (SFTP).

Encryption and Security

​In simple words, encryption transforms your data into an unreadable format before it is transmitted. The goal is to make data recovery mathematically impossible without the correct decryption key. Since the standard FTP protocol transmits data in the clear, it is upgraded to FTPS with SSL/TLS which is used to wrap the plaintext traffic in a secure tunnel. FTPS uses X.509 digital certificates to verify the authenticity of the server. When properly configured with modern TLS versions, FTPS provides strong protection against interception and unauthorized access.

SFTP, on the other hand, relies on the underlying SSH layer to protect data privacy. Instead of certificates, it typically uses SSH host key fingerprints to verify the identity of the host. Similar to SSH, SFTP is also a packet-based network protocol.

Firewall Traversal

A major factor in the secure FTP vs SFTP choice is network configuration.

File transfer protocol requires a control channel and a data channel to complete a session of the file transfer. There are two approaches to establishing a data connection: the active mode and the passive (PASV) mode. In active mode, the server needs to initiate a socket connection to the client, which is often not practical since most client devices are behind a NAT firewall. Passive FTP, on the contrary, requires the client to fire another connection to the server for data transfer. Again, this gives rise to the firewall problem on the server side if it is behind a NAT router. Since the FTP data port is chosen randomly for each FTP client, a range of ports must be opened for FTP on the firewall, which potentially increases the attack surface. 

SSH file transfer protocol, however, only needs one SSH port (e.g., 22) to send and receive commands and data. This makes the firewall configuration relatively simple and ensures minimal exposure.

Compliance Considerations for FTPS and SFTP

​Businesses handling healthcare records, financial transactions, legal documents, customer information, or confidential enterprise data often require secure file transfer protocols that support compliance regulations.

Both FTPS and SFTP can help organizations meet security and compliance requirements such as:

• HIPAA
• PCI-DSS
• GDPR
• SOC 2
• ISO 27001

​FTPS vs SFTP: Head-to-Head Comparison

​To make the differences easier to understand at a glance, here is a clear side-by-side comparison between FTPS and SFTP:

​Feature​	​FTPS	​SFTP	​Winner/Better For
​Security Layer​	​SSL/TLS	​SSH	​Tie​
​Default Port​	​21/990	​22	​-
​Firewall / NAT Friendly​	​Usually requires opening multiple ports (for command and data channels)​	​Excellent (uses single port 22)​	​SFTP
​Authentication​	​Password + Client Certificates (optional)​	​Password + SSH Keys (more secure)​	​SFTP
​Speed	​Generally faster for large file transfers​	​Slightly slower but consistent​	​FTPS
​​Ease of Setup​	More complex due to certificate management​	​Simpler, especially with SSH keys​	​SFTP
​Legacy System Support​	​Very good​	​Limited​	​FTPS
​Compliance & Auditing​	​Strong	​Very Strong​	​Tie
​Platform Support​	​Broad	​Broad (especially Linux/Unix which come with OpenSSH)​	​Tie

​SFTP vs FTPS: Which is more secure?​

In the battle of FTP over SSL vs SFTP, both offer solid protection if configured correctly. We know that FTPS and FTPES are protected by SSL/TLS, and SFTP are protected by SSH (Secure Shell). They are as secure as their underlying encryption layers. SSL and SSH suffered various vulnerabilities and exploitations during their evolutions at the protocol or the implementation level. Below we highlight some of them.

SSH (Secure Shell)

​SSH doesn't offer a digital certificate mechanism as SSL does. Verifying the authenticity of an SSH host relies on the fingerprint of the SSH host key. A valid SSL certificate, based on the sophisticated X.509 standard, ensures that you connect to a host that is what it claims to be by its domain name.

Secure Sockets Layer (SSL)​

​The Heartbleed Bug was found in the well-known SSL library OpenSSL, which allows attackers to access private information such as usernames and passwords.

POODLE attacks are a common threat to the SSL/TLS protocol. An attack targeted to cause connection failure can lead to protocol version negotiation. Once the SSL version downgrades to 3.0, the ciphers used in the protocol give way to a successful poodle attack. 

Which one to choose: FTPS or SFTP

To summarize, both FTPS and SFTP offer solid security and protection as long as their underlying cryptographic socket layer is secure and vulnerability-free. 

However, SFTP is often considered easier to secure because it relies on a single SSH connection and avoids the multiple channel complexities associated with FTP over SSL/TLS and is more firewall-friendly.

FTPS remains an excellent solution for organizations that depend on legacy FTP infrastructure or SSL/TLS certificate-based authentication. Secure FTP should be used with the most updated version of TLS for the best protection.

The best option ultimately depends on your:

• Existing infrastructure
• Firewall architecture
• Compliance requirements
• Automation needs
• Enterprise workflows

For modern enterprise environments focused on automation and simplified security management, SFTP is commonly preferred.

For businesses already invested in FTP infrastructure, FTPS continues to provide reliable and secure encrypted file transfers.

TurboFTP provides enterprise-grade secure file transfer solutions supporting both FTPS over SSL/TLS and SFTP over SSH2, helping organizations automate, secure, and manage sensitive file transfers across Windows enterprise environments.

​Frequently Asked Questions​

​What is the difference between FTPS and SFTP?​

FTPS uses SSL/TLS encryption on top of the traditional FTP protocol, while SFTP uses SSH encryption through a completely different protocol architecture.

​Is FTP over SSL the same as FTPS?

​Yes. FTP over SSL and FTPS are commonly used interchangeably to describe FTP secured with SSL/TLS encryption. As we mentioned above, there are two types of FTPS: Explicit FTPS (FTPES) and Implicit FTPS.

​Which is more secure: FTPS or SFTP?

​Both are secure when configured properly, but SFTP is generally considered easier to secure and manage in modern enterprise environments.

​Which protocol is better for firewall traversal?

​SFTP is generally better for firewall traversal because it uses a single encrypted connection over port 22.

​Can FTPS and SFTP support compliance requirements?

 Yes. Both protocols can support compliance frameworks such as HIPAA, PCI-DSS, GDPR, and SOC 2 when implemented correctly.