What Is SFTP? Secure File Transfer Protocol Explained

As a web developer, I use SFTP all the time to upload my website files to the server, but because it’s so seamless, I rarely think about how it actually works.

SFTP, or Secure File Transfer Protocol, is a method to transfer your files over the Internet in a way that prevents other people from intercepting them.

You can think of SFTP like a Brink’s truck — an armored car that carries valuables from bank to bank. The “armor” in the case of SFTP is encryption.

Encryption makes the contents of your files unreadable to those without the right decryption key. As a result, even if someone with malicious intentions intercepts the files, they won’t be able to read them.

That’s just the gist of it. Join me on this journey to explore SFTP in detail, including what it entails, how to set it up, and best practices.

Okay, I admit that while I may use SFTP all the time, I had to give myself a refresher on how it works. After all, all of this happens behind the curtain, so to speak. Here’s a crash-course version of what I learned:

Underlying Technology and Protocols

I’ve already explained that SFTP creates a secure connection between a client and a server. Once this connection has been established, you can transfer files securely.

SSH (Secure Shell) is what creates this secure connection by encrypting any data transferred via SFTP.

The transfer process can be anything from uploading, downloading, renaming, and deleting files. All of these processes happen while keeping the data secure and private.

Another thing to note is that SFTP uses strong encryption algorithms to secure data in transit. What this means is that even if data is intercepted, it cannot be read without the correct decryption keys.

It’s like accessing your favorite movie streaming service and browsing its catalog, but not being able to watch anything without the correct username and password.

History and Development of SFTP

I’m going to take you back to high school for a history lesson for a moment. SFTP was created by Tatu Ylönen back in 1995. At the time, developers were looking for a more secure way to transfer files.

Yes, they had traditional FTP, which dates back to the early days of the internet in the 1970s, but it lacked security features. That made it vulnerable to interception and attacks by malicious parties.

As the internet grew, so did the popularity of sensitive data transfers. I’m talking about things like:

• Financial information
• Medical records
• Social security numbers (and other personally identifiable information)
• Legal documents

Since cybercriminals were working overtime to get any information they could use for criminal activities like identity theft, the need for a secure file transfer method became apparent and even more pressing.

Today, as illegal as it is, cybercrime is a $1.5 trillion empire.

Now you can imagine the kinds of inventions and investments that were (and still are) necessary to keep malicious parties at bay. SFTP was one of these inventions.

It was initially released as part of the SSH (Secure Shell) protocol suite. SSH was designed to provide secure remote login and command execution, and it was just a matter of time before secure file transfer capabilities were introduced.

In any conversation about SFTP, you’ll likely hear these additional acronyms: FTP and FTPS. I know you must be thinking, “Wait, FTPS…where did that one come from?!” I promise we’re almost done introducing acronyms. Here are the key differences that set these apart:

I’ve already mentioned how SFTP has a lot of benefits over FTP, but here’s a quick summary if you don’t want to read the table:

• Enhanced security
• Simple firewall configuration
• Multiple authentication methods
• Data integrity

With that out of the way, I’ll dig deeper into its key features in the section below.

Just like a Brink’s armored car does more than protect valuable assets, SFTP does more than encrypt your files. These are the main features you should know:

Secure Data Transfer

One of SFTP’s standout features is its end-to-end encryption. This is like the armor on the outside of the Brinks truck.

In simpler terms, it encrypts data before it leaves your device and keeps it encrypted until it reaches its destination.

As we saw earlier, end-to-end encryption ensures that even if someone intercepts the data in transit, they won’t be able to read it. All they’ll get is a bunch of unreadable junk data.

With SFTP, your data is protected from interception and tampering. The secure channel created by SSH means that any data transferred is safe from prying eyes and unauthorized modifications. This helps maintain the integrity and confidentiality of your information.

Authentication Methods

SFTP supports traditional password-based authentication — this is just a fancy way of saying it supports usernames and passwords. A word to the wise: please don’t use passwords like “12345.” Choose something stronger with a good mix of letters and numbers.

To access the SFTP server, you need to provide a valid username and password.

This method is pretty straightforward and easy to use. After all, you do it for your Facebook and online banking accounts.

For an added layer of security, SFTP also supports something called public key authentication. This involves generating a pair of cryptographic keys: a private key that remains on your device and a public key that is placed on the server.

You’ll be granted access only if the server can verify the private key corresponding to the public key. This is more advanced and secure than using traditional usernames and passwords.

File Management Capabilities

SFTP isn’t just about transferring files. You can use this authentication method to manage files on a remote server. By file management, I mean tasks such as uploading, downloading, deleting, and listing directory contents, all within a secure environment.

Another unique feature of SFTP is its ability to resume interrupted transfers.

Let’s say a file transfer has been interrupted for some reason; in this case, you don’t have to start over from the beginning. With SFTP, you can pick up right where you left off, saving you time and bandwidth.

Compatibility and Integration

SFTP is also highly compatible with various platforms and software, including — but not limited to — Windows, macOS, Linux, and various Unix systems. That’s also what makes it a versatile choice. With SFTP, you don’t need to stress about your operating system.

You can integrate it with a lot of systems and applications, too. Whether you’re using it for automated backups, web application integration, or enterprise resource planning (ERP), it fits the bill.

Imagine you had a million dollars worth of precious diamonds inherited from your late aunt. Would you have your cousin pick them up from the safety deposit box in her Subaru,or would you take the extra precaution to hire a secure transport service? I don’t know about you, but I would definitely use the more secure option!

Now, I understand your website files may not be as valuable as precious gems, but seeing as how you can get SFTP for free with little effort, why wouldn’t you use it? I prefer using SFTP over traditional FTP for obvious security reasons, but there are a lot of other benefits worth exploring. Here are some of the main reasons I recommend using SFTP:

Enhanced Security

One does not simply discuss the benefits of SFTP without mentioning its deep focus on security!

SFTP promotes the confidentiality, integrity, and authenticity of your data as you move it from point A to point B.

What does this mean? Thanks to SSH, your files are protected from unauthorized access, keeping them confidential.

Data integrity, on the other hand, is maintained by preventing any tampering during transmission; it’s similar to the person who takes inventory when loading and unloading an armored car. This makes sure that the files received are exactly as they were sent.

Finally, SFTP also verifies the authenticity of both the server and client to make sure that everyone is who they say they are. This protects against common digital threats like man-in-the-middle attacks, data breaches, and eavesdropping.

Compliance With Standards and Regulations

Earlier, I shared that SFTP came into the picture to protect sensitive information in transit online. This requirement is especially important for businesses with industry-specific compliance requirements. As a consumer, this is something you should definitely care about.

Take the healthcare industry, for instance. SFTP supports HIPAA (Health Insurance Portability and Accountability Act) compliance by making sure patient information isn’t easily readable by third parties.

This means that when you visit your online health portal with notes about your recent office visit, your information stays protected.

The same applies to businesses operating in the European Union or targeting EU citizens; SFTP adheres to GDPR (General Data Protection Regulation) standards by protecting personal data during transfers.

Reliability and Performance

Even though SFTP came around in the ’90s, its popularity today tells the story of its reliability and performance. It’s really the golden standard for transferring files from one place to another.

One of its key features is the ability to resume interrupted transfers, as I noted earlier. This unique trait reduces the likelihood that you lose data, and it saves you from lengthy re-transfers of large files.

Additionally, SFTP supports many different file management operations. Now you understand the reason it’s widely considered a versatile tool for comprehensive file handling.

Ease of Use and Flexibility

Since SFTP is so user-friendly, it works no matter what your technical skill level is. I started using it as a newbie developer and haven’t looked back since. In fact, you’ll notice that most SFTP clients out there have intuitive graphical user interfaces (GUIs) that simplify file transfer processes.

These interfaces usually have drag-and-drop functionality, which makes it easy to move files between local and remote systems without the need for complex commands.

To make these tasks even easier to execute, most SFTP clients have tools for scheduling transfers, automating repetitive tasks, and managing files.

One more thing: SFTP also supports many different file types and sizes, from small and large multimedia files to complex data sets. This flexibility comes in handy for businesses that deal with diverse data types and need a reliable method for transferring files of any size.

Okay, so if you’re an absolute beginner with zero experience building websites or transferring files, this process may seem a little daunting at first. However, I promise it’s not as complicated as it sounds. Here’s what you need to know:

Choosing an SFTP Client and Server Software

Before you set up your SFTP software, you need to choose one (duh).

Let’s start with a few I recommend.

FileZilla tops my list because of its user-friendly interface. It’s not one of those software programs where you have to dig through tons of tutorials to figure out how it works — this is the one that I use.

Then there’s WinSCP, best known for its integration with Windows and ease of use.

Alternatively, you can opt for OpenSSH. It works best on Unix-based systems.

Here are the features I look for in SFTP tools:

• An intuitive and easy-to-navigate interface
• Fast and reliable file transfers, with support for resuming interrupted transfers
• Compatibility with various operating systems
• Integration with other software
• Comprehensive guides, tutorials, and customer support for troubleshooting
• Automation features like scheduling and script support
• Strong encryption and support for various authentication methods
• Detailed logs and monitoring tools to track file transfers and detect any issues

As long as you choose SFTP software with these features, it’ll be smooth sailing for you.

Installing and Configuring an SFTP Server

It’s important to know how to set up the server software and make sure it’s properly configured to handle secure file transfers. To get started, download your chosen server software and follow the installation instructions provided.

Let’s say you want to download and install FileZilla. You’ll find the download link on the home page of the free FTP client.

Once you’ve downloaded the software, follow the prompts on your screen to install it.

During the initial configuration, you’ll need to set up user accounts and permissions, configure SSH keys for secure authentication, and ensure the server is listening on the correct port.

Initial configuration tips and best practices:

• For security, create a separate user account specifically for SFTP access.
• Make sure that directory permissions are correctly configured to prevent unauthorized access.
• Keep detailed logs of all connections and transfers to monitor for any suspicious activity.
• Enforce strong passwords and consider using SSH keys for authentication to enhance security.
• Conduct regular system audits and monitor access logs for unusual activity.
• Restrict server access to specific IP addresses or ranges to reduce the risk of unauthorized access.
• Regularly back up your server configurations and important data to recover quickly in case of failure or attack.
• Implement two-factor authentication to require a second form of authentication besides just a password or key.
• Conduct thorough testing to make sure that the server and all security measures are working correctly.

If you configure everything correctly, it makes file transfers a lot easier down the road.

How to Connect to an SFTP Server

Setting up an SFTP client should be your next move. Here’s how to go about it:

First, install your chosen client software and launch it to begin configuration. Enter the server’s hostname or IP address, port number, and your login credentials.

Tip: Unless stated otherwise, 22 is the default port number.

If you decide to use public key authentication, you’ll also need to specify the path to your private key file. Once you’ve entered everything correctly, you can establish a secure connection to the server.

Basic SFTP Commands and Operations

To get the most out of SFTP, you should know and understand a few basic commands.

Here are the ones I use the most:

• put: Uploads (or puts) a file from your local system to the remote server.

Example: `put localfile.txt /remote/path/`

• get: Downloads (or gets) a file from the remote server to your local system.

Example: `get /remote/path/remotefile.txt`

• ls: Lists the files and directories in the current remote directory.

Example: `ls /remote/path/`

• cd: Changes the current remote directory.

Example: `cd /remote/path/`

With these commands, you can perform basic file operations on the remote server. For instance, you might use `put` to upload a report to a shared server or `get` to download a backup file. The `ls` and `cd` commands help you navigate the server’s file system.

As you get more used to SFTP, you can implement certain advanced tips and best practices to optimize performance, enhance security, automate tasks, and troubleshoot common issues. These strategies will help you get the most out of SFTP in various scenarios. Let’s check them out.

Optimizing SFTP Performance

Consider tuning both your network and server settings. This includes optimizing bandwidth, minimizing latency, and making sure that your server has enough resources to handle file transfers efficiently.

Best practices for large file transfers:

• Enable compression to reduce the size of files and increase speed during transfer.
• Split large files into smaller chunks to avoid transfer timeouts and make the process more manageable.
• Perform large file transfers during times of low network activity to avoid congestion and ensure faster speeds.
• Adjust TCP window size and buffer settings for better throughput.
• Set higher priority for the most important transfers to ensure they are completed faster.
• Transfer multiple files simultaneously to maximize bandwidth usage.
• Regularly check network performance and adjust settings as needed for optimal transfer speeds.
• Set bandwidth limits to prevent SFTP transfers from consuming all available network resources.
• Host SFTP on a dedicated server to avoid resource contention with other services.

For best results, consider creating a checklist of the most important tasks from the list above and then implementing them one by one.

The truth is that modern IT infrastructure is not what it used to be back in the 1990s, when SFTP first entered the scene. So much has changed over the past few decades. In this section, I’ll explain how SFTP works with modern IT infrastructure.

Role of SFTP in Cloud Computing

Today, SFTP integrates with cloud storage solutions to enable secure and efficient data transfer to and from cloud environments. This integration supports hybrid cloud strategies, where data moves between on-premises systems and the cloud seamlessly.

SFTP also facilitates secure data transfers between cloud and on-premises systems. This helps protect sensitive information during migration or backup processes.

SFTP for DevOps and CI/CD Pipelines

In certain environments, you might have to keep both development and operations running simultaneously. That’s where SFTP comes in to facilitate automated deployments and configuration management.

In other words, SFTP makes sure that code, system settings, and assets are securely transferred between development, staging, and production environments.

Within development workflows, teams can use SFTP to share code, assets, and data securely. The main goal here, besides the obvious need to transfer files from one point to another, is to maintain high levels of integrity and confidentiality throughout the development process.

I expect SFTP to play an important role in the digital era. The rising cases of cybercrime, in particular, have made SFTP one of the most sought-after file transfer processes.

Now and moving into the future, the importance of user authentication is pretty evident. Come to think of it, you need to verify your identity on almost every application you interact with these days.

One study found that the use of 2FA has increased by about 51% from 2017 to 2021.

Whether it’s your social media account, financial application, medical chart, or anything in between, two-factor authentication is almost an industry standard at this point in time.

Then there’s the role of AI. It’s nearly impossible to discuss the future of any form of technology today without mentioning AI. This technology is expected to help improve automation and predictive analysis in SFTP. As a result, using SFTP will be much easier, more convenient, and more secure than ever.

Three things make STFP particularly stand out: security, performance, and versatility. Even better, you don’t need to be a tech guru to understand how this process works.

While it’s not a plug-and-play type of technology, it’s pretty easy to figure out how it works.

That alone makes SFTP so accessible, and it’s not something that’s only reserved for big corporations with in-house IT departments.