FTP vs SFTP: Which Protocol is Better for File Transfer?

FTP vs SFTP: Which Protocol is Better for File Transfer? Sharing data over the internet is a critical process that requires use of suitable channels that facilitate the transfer. Well, FTP and SFTP are among the most popular protocols for transferring data. At the core of their functionality, they provide a channel for transferring data between clients and servers.

Let’s start with article FTP vs SFTP: Which Protocol is Better for File Transfer?

What is FTP and How Does it Work?

FTP (File Transfer Protocol)is a standard communication protocol used to transfer files between computers. It provides access to folders or directories on remote computers. With FTP, files are transferred over TCP/IP networks. It uses a client-server model, whereby clients initiate communications with servers awaiting incoming requests.

How does FTP work?

When you transfer files between 2 computers on a similar local network, you need to select files or folders and share from one PC to the other. However, this is impossible when sharing files between computers located in different geographical locations. You need an internet connection and a special channel. Here is where FTP comes to place.  Well, with FTP file transfer works efficiently between computers miles apart.

All you need is FTP client installed on your computer. Besides, an FTP server installed on the computer to send data to. Then, you must provide the FTP client with the server address, username, and password. After that, the client connects to the server, allowing you to share files. Either upload files (share files from your computer to the server), or download files (transfer files from the server to your computer). 

There are 2 different types of FTP connections:

  • Active connection: The client establishes the command while the server establishes the data channel. After the client requests data over the connection, the server proceeds to initiate a transfer.
  • Passive connection– The client establishes both the command and transfer connections. After the client requests data, the server provides a random port number. Once the client receives the port number, the data connection is established, allowing files to move from the server to the client.

Up next with article FTP vs SFTP: Which Protocol is Better for File Transfer? is to introduce features of FTP Server. 

Features of FTP

Control Connection

Manages communication between the client and server during an FTP session. After initiating a transfer, the client establishes a control connection with the server. It remains active throughout the session. All command and response information is exchanged through the control connection. Commands are various requests from the client to the server, such as to retrieve a file, send a file, etc. The server responds through the same control connection, thus confirming whether the command was executed or denied.

Data Connection

A distinct pathway specifically established for transferring files between the client and server. Unlike the control connection, a data connection is not persistent. Instead, it is set up when there is a file to be transferred. This connection closes immediately the transfer is complete. This ensures efficient usage of network resources. Data connections are responsible solely for the transportation of files, while all command and control functions are carried out through the control connection.

Transmission Modes

Basically, FTP supports 3 transmission modes for sending data: Stream, Block, and Compressed. Stream mode sends data as a continuous stream of bytes. Block mode, on the other hand, breaks the data into blocks, each block sent separately with a header for error and flow control. This provides better error checking compared to the Stream mode. Lastly, Compressed mode reduces the size of the data before transmission to save bandwidth. Beneficial when transferring large files over slower connections.

Error Control

Solves any errors that occur during transmission. Once it detects an error, FTP requests the file to be resend. This error control checks, if the data needs to be resent, as well as data corruption. It enables FTP to provide reliable file transfer and ensures that the client receives files as intended.

Pros of FTP

  • Fast data transfer with minimal overhead.
  • Binary and ASCII transmission modes ensures files don’t change when in transit.
  • Transfers multiple directories at once.
  • No limit to the size of files you transfer.
  • If FTP connection is lost during transfer, the transfer resumes when the connection is restored.

Cons of FTP

  • Usernames and passwords are shared in plain text which is dangerous.
  • Does not encrypt data in transit.
  • Limited logging and reporting which leads to minimal auditing capabilities.

Keep on reading FTP vs SFTP: Which Protocol is Better for File Transfer?

What is SFTP and How Does it Work?

SFTP is called Secure File Transfer Protocol for transferring data over the internet. Contrary to its name, SFTP isn’t just an improved version of FTP. Rather, it’s a unique transfer protocol designed by the Internet Engineering Task Force (IETF). It uses SSH encryption to securely transfer files, needing authentication keys on both the client and server side. With SFTP, choose the level of authentication you want for your files.

Secondly, SFTP works in a client-server model reinforced by SSH. Basically, SSH is a cryptographic network protocol built for secure communication across an insecure network. When an SFTP session starts, the client initiates an SSH connection to the server. To transfer data, a pair of cryptographic keys is generated. The public key is stored on the server, while the private key resides on the client. These keys help with encryption and decryption of data, as well as verifying identity.

The server creates a separate SFTP subsystem. Thus, data transferred using SFTP is secure from potential threats such as interception and unauthorized access, thanks to its integrated SSH encryption. The protocol ensures secure authentication and data privacy, maintaining the integrity of the data throughout the transfer process.

After successful authentication, an SFTP session starts over the established connection. At this point, the client executes SFTP commands. Following that, SFTP allows various operations on remote files. Also supports actions like listing directory contents, and deleting and renaming files. Besides, you create and remove directories and read and write to files on a remote server.

Features of SFTP

Flexible Deployment

Runs on multiple platforms including Linux/Unix, Windows, Solaris, AIX, and IBM. Besides, deploy it on cloud platforms such as Azure and AWS. If you need a highly flexible solution, deploy an SFTP server in Docker, and manage it using Kubernetes.

Data Encryption via a Secure SFTP Server

Employs encryption on data in transit, eliminating the risk of unauthorized access. It uses encryption algorithms to encrypt data from server to client.

IPV6/HTTP Support

Supports both IPv6 and HTTP to securely transfer files using IPv6 and handles HTTP requests and responses for accessing and displaying web pages.

Public Key Authentication

Since SSH uses public key authentication rather than password based authentication. Initially, a public and a private key are generated. These keys are related, and data encrypted with one key to be decrypted by the other key. The public key is usually uploaded to the server. When a client connects with the server, it provides the private key as proof of identity. This creates a secure connection between the server and the client.

Pros of SFTP

  • Aids secure data connection using SSH.
  • Encrypts data in transit to prevent data unauthorized access.
  • Easy to use behind a firewall since it only requires one port.
  • Helps achieve compliance against major standards such as HIPAA, SOC2, etc.

Cons of SFTP

We have arrived at the main part of FTP vs SFTP: Which Protocol is Better for File Transfer?

FTP vs SFTP: What is the difference?

Security Approach

FTP lacks inherent security mechanisms, which is one of its main shortcomings. It transfers data over networks without encryption, so vulnerable to unauthorized access. Basically, anyone with access to the network potentially accesses and manipulates your data.

On the other hand, SFTP provides an encrypted channel for file transfer, adding a layer of security that FTP lacks. When using SFTP, your data is encrypted into an unreadable format while in transit. Even stolen data m can’t be interpreted without proper decryption key. This protective layer secures both the file contents and any associated commands. Moreover, SFTP authenticates the server, ensuring the client is connected to the correct server. Thus, SFTP provides a closed channel for secure file transfer.

Architecture Design

Both FTP and SFTP use a server-client architecture. In FTP, the client initiates a connection with the server to request the file transfer. FTP uses 2 separate connections for control commands and data transfer (TCP/IP) to pass commands from the client to the server. However, the data connection delivers the actual file transfer.

Contrarily, SFTP uses SSH to transfer files from server to client. Unlike FTP, SFTP uses a single connection for both the data and command information. After establishing a connection, the client performs various operations such as reading remote files, listing directory contents and more.

Firewall Support

Here, FTP poses numerous challenges when it comes to firewall support. Uses 2 separate connections to carry out file transfers: a control and a data connection. The control connection mostly happens on a predictable port, usually port 21. However, the data connection may be initiated on any number of arbitrary ports. This variability makes it difficult for a firewall to know which incoming connections is allowed. Therefore, a firewall needs to actively monitor the FTP control connection and allow incoming data connections. This process is complex to set up and maintain, making FTP less friendly for firewall configurations.

But the SFTP is easier to work for firewall configurations. Unlike FTP, SFTP only uses one connection for both control commands and data transfer. Connection is established over a single port, usually port 22. This makes it much simpler for a firewall to manage, as it allows traffic through one designated port. The single port setup is simple to set up especially for large organizations with robust firewalls. With SFTP, there’s no need for a firewall to actively monitor multiple connections or dynamically open and close various ports.

Transfer Speeds

Continuing with FTP vs SFTP: Which Protocol is Better for File Transfer? There is faster file transfer speeds with FTP than SFTP in some cases. Primarily due to its simpler design. Well, FTP uses separate channels for command and data transfer, reducing the amount of information that must be transmitted together. Besides, there is no encryption involved, which means less computational overhead.

But, SFTP is relatively slow as the encryption adds resource overhead. This encryption process takes computational power and time, which slows down the overall transfer speed. However, the difference in speed may not be noticeable for small file transfers. For larger files, SFTP is slower than FTP.

Binary and ASCII Data Transmission

Here, FTP has 2 modes for data transmission: ASCII and binary. ASCII is used for transferring text files. Converts some aspects of the file according to the requirements of the target system i.e UNIX, Windows, etc. Binary mode is used for non-text files such as executable files, videos, and images. In binary mode, files are transferred byte for byte without any conversion or special handling. This ensures that the exact copy of the file is transferred without any loss of data, which is crucial for these types of files.

Crucially, SFTP lacks an ASCII mode, but rather, operates only in binary mode. It does not convert data or change it during the transfer. In essence, it sends all data in binary mode, such that the server receives the data as sent by the client. SFTP does not distinguish between text and non-text files, meaning it doesn’t have separate ASCII and binary modes like FTP. This ensures the integrity of the transferred data, whether it’s text or non-text. However, it makes logging extremely complex, and organizations have to rely on Managed File Transfer (MFT) tools to bypass this challenge.


Both FTP and SFTP are used through a command line interface (CLI) on most major operating systems. With FTP, it has relatively simpler CLI commands compared to SFTP. These commands are limited in functionality, and only allow users to access and retrieve files hosted in a remote connection without necessarily making any changes to the files or directories. Some of the FTP commands include:

  • open/close- for starting/terminating connections
  • ls – for listing file names
  • cd- for changing working directory on the FTP server
  • size- determining the size of a file

On the other hand, SFTP has more commands which provide the user more functionality than FTP. 

  • mkdir- create new directories.
  • chown- change file ownership.
  • chmod- change read, write, and execute permissions on files.
  • symlink/ln -create a shortcut link to a remote file.

These commands allow SFTP clients to perform more actions on files compared to FTP clients.

Thank you for reading FTP vs SFTP: Which Protocol is Better for File Transfer? We shall conclude the article now. 

FTP vs SFTP: Which Protocol is Better for File Transfer? Conclusion

Both. FTP and SFTP protocols are ideal commands for sharing data between computer systems on different networks. Both protocols operate on the client-server model, but differ significantly in terms of security and authentication. SFTP is more secure thanks to SSH which provides encryption and key authentications. But, FTP is faster and uses both binary and ASCII transmission modes. SFTP has become mainstream as it’s secure from malicious attacks and complies with many regulatory standards. Therefore, it’s imperative to choose SFTP over FTP, due to its security approach. Consider combining both,  especially when transferring less sensitive data such as videos and images.

Avatar for Dennis Muvaa
Dennis Muvaa

Dennis is an expert content writer and SEO strategist in cloud technologies such as AWS, Azure, and GCP. He's also experienced in cybersecurity, big data, and AI.

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