File Transfer Protocol (FTP) has long been a staple in the world of data transfer, serving as a widely used method for sending files between remote systems. However, as of 2022, it has largely fallen out of favor due to significant security vulnerabilities. Modern software now deprecates FTP in favor of more secure alternatives, leaving it relegated mainly to legacy applications.

One such alternative is Secure File Transfer Protocol (SFTP), which is a distinct protocol integrated within the Secure Shell (SSH) framework. SFTP allows users to execute FTP commands over an encrypted connection, making it a secure and versatile choice for file transfers. In most cases, SFTP can seamlessly replace FTP, offering a secure way to manage file transfers in environments where FTP was previously utilized.

When it comes to security, SFTP is far superior due to its encryption protocols and the ability to leverage existing SSH connections. Unlike FTP, which is inherently insecure and should only be used in trusted networks, SFTP provides a secure environment for transferring sensitive information.

This guide aims to showcase how to use SFTP through its interactive command line interface, rather than relying solely on graphical tools, which often come with their own complexities.

By default, SFTP utilizes the SSH protocol for authentication and establishing secure connections, allowing for a variety of authentication methods similar to those used in SSH. While default authentication can be achieved using passwords, it is highly recommended that users create SSH keys for additional security. Transferring your public key to any remote systems you intend to access will not only enhance your security but can also save time in the long run.

If you are unsure about how to set up SSH keys for accessing your server, refer to our comprehensive guide available on the topic.

Once you have established SSH access, you can easily transition to using SFTP for file management. To test your SSH connection, enter the following command:

ssh sammy@your_server_ip_or_remote_hostname

If this command successfully connects, you will exit the SSH session by typing:

exit

To initiate an SFTP session, use the following command:

sftp sammy@your_server_ip_or_remote_hostname

Your prompt will switch to an SFTP prompt, indicating you are now connected to the remote system. If you are working on a custom SSH port instead of the default port 22, you can open an SFTP session as follows:

sftp -oPort=custom_port sammy@your_server_ip_or_remote_hostname

Once connected, one of the most valuable commands to familiarize yourself with is the help command, which provides a summary of other SFTP commands available to you. You can access this by typing either:

help

or

?

This command will display a list of available commands, including:

  • bye - Quit SFTP
  • cd path - Change remote directory to 'path'
  • chmod mode path - Change permissions of the file located at 'path'
  • get remote local - Download file from remote to local
  • put local remote - Upload file from local to remote
  • exit - Quit SFTP

We will delve deeper into some of these commands in the following sections.

As you navigate through the remote system's file hierarchy, many commands will function similarly to their shell counterparts. For orientation, you can find out your current directory by typing:

pwd

This will return the remote working directory, for example:

Remote working directory: /home/demouser

To view the contents of the current remote directory, you can use the ls command:

ls

The output may look something like this:

Summary.txt info.html temp.txt testDirectory

While the commands in the SFTP interface may not offer the same range of features as typical shell commands, they do support essential flags, such as:

ls -la

This will display additional metadata and permissions about the files in the directory:

drwxr-xr-x 5 demouser demouser 4096 Aug 13 15:11 .

To navigate to another directory, use the cd command followed by the directory name:

cd testDirectory

If you need to access your local file system while in SFTP, commands can be prefixed with an l to direct them to the local file system instead. For instance, to print the local working directory:

lpwd

The output would be:

Local working directory: /Users/demouser

To list the contents of your local directory, you can use:

lls

Similarly, changing directories on the local machine is possible with:

lcd Desktop

Downloading files from a remote host is straightforward with the get command:

get remoteFile

This command fetches the specified file from the remote server to your local system, and you can also rename it if needed:

get remoteFile localFile

For downloading entire directories and their contents, add the recursive option:

get -r someDirectory

When uploading files to the remote system, the put command works similarly:

put localFile

To maintain the original permissions and timestamps of files during transfers, use the -P or -p flags:

put -Pr someDirectory

For those needing to check available disk space before initiating transfers, utilize the df command:

df -h

In scenarios where you encounter a Permission Denied error while attempting to upload files, it usually indicates inadequate permissions for the user on the target directory. To rectify this, you may need to adjust the ownership or permissions of the target directory using commands like ls -ld, chown, and chmod.

Connecting to an SFTP server may lead to other familiar errors such as Connection Refused or Timed Out, typically tied to network issues or server-side SSH service problems. Its essential to ensure that the SSH service is operational and that the correct server IP and port are being used.

Ultimately, SFTP stands out as a reliable, secure protocol for transferring files over networks, built directly into SSH, thereby offering an encrypted method for accessing and managing files remotely. Its utility extends beyond simple transfers; it can also be integrated into CI/CD pipelines for secure deployments.

For those who may have previously relied on FTP or SCP, transitioning to SFTP is a wise choice, enabling users to harness the security features of SSH alongside the conveniences of file management capabilities.

To further enhance your understanding of secure file transfers and remote management, consider exploring additional tutorials available that cover various aspects of SFTP and SSH usage.