How SFTP and FTP are Different Protocols

How SFTP and FTP Are Different Protocols

SFTP (Secure File Transfer Protocol) and FTP (File Transfer Protocol) may both be used for file transfers, but they are fundamentally different protocols in their design, security mechanisms, and underlying technologies.

1. SFTP (Secure File Transfer Protocol):

• Not an Extension of FTP: SFTP is not related to FTP. It’s a completely different protocol built on top of SSH (Secure Shell), which is used for secure remote system administration.
• Security via SSH: SFTP operates entirely within the SSH protocol. SSH provides both encryption and authentication, ensuring that data and login credentials are always secure. All file transfers, commands, and communication are encrypted.
• Port: SFTP operates over port 22, which is the same port used by SSH.
• Connection: SFTP uses a single connection for both control and data transfer. The entire session is encrypted within the SSH tunnel, providing a secure connection for both sending and receiving files.
• Additional Features: SFTP also includes features beyond just file transfers, such as remote file management (creating, deleting, renaming files) over the secure SSH connection.

2. FTP (File Transfer Protocol):

• Separate Protocol: FTP is an older protocol designed specifically for file transfer. It was created long before encryption became a standard security practice.
• Insecure by Default: FTP does not provide any encryption. Both file data and login credentials (username and password) are transferred in plain text, which makes it vulnerable to eavesdropping and attacks.
• Port: FTP uses port 21 for control commands and port 20 for data transfer.
• Security via TLS (FTP Secure): To address its lack of encryption, FTP can be secured using TLS (Transport Layer Security). This secure version is commonly known as FTPS. TLS adds encryption to the FTP protocol, protecting data and login credentials during transfer.

Key Differences Between SFTP and FTP:

1. Underlying Protocol:
   • SFTP: Uses SSH (Secure Shell), a completely separate protocol designed for secure connections.
   • FTP: Uses its own protocol but can be enhanced with TLS (FTPS) for encryption.
2. Security:
   • SFTP: Fully encrypted and secure by default, with both the control and data transfer encrypted inside the SSH tunnel.
   • FTP: Insecure by default. When using TLS (FTPS), encryption is added, but plain FTP remains vulnerable.
3. Ports:
   • SFTP: Uses port 22 (SSH).
   • FTP: Uses port 21 (control) and port 20 (data).
4. Connections:
   • SFTP: Uses a single connection for both commands and data transfer, with everything secured by the SSH tunnel.
   • FTP: Uses two separate connections: one for control commands and one for data. When encrypted with TLS (FTPS), these connections can be secured individually.
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How FTP Uses TLS for Security (FTPS)

When FTP is secured using TLS (FTPS), there are two modes of operation: Explicit TLS and Implicit TLS.

1. Explicit TLS (FTPES):

• In Explicit TLS, the client initially connects to the server using the standard unsecured FTP port (port 21).
• After establishing the connection, the client explicitly requests to upgrade the connection to a secure TLS connection using the “AUTH TLS” command.
• Once the server agrees, the control and/or data channels can be encrypted with TLS.
• Port: Explicit TLS uses port 21 for the initial control connection. The data connection may use a dynamic port (negotiated between the client and server) and can also be encrypted.

2. Implicit TLS:

• In Implicit TLS, the connection is assumed to be secure from the start.
• The client connects to the server over a dedicated port 990, and the connection is immediately encrypted using TLS.
• There is no negotiation to upgrade to TLS—the connection is already secured when it begins.
• Port: Implicit TLS uses port 990 for control commands, and a dynamically negotiated port for data transfer, both of which are encrypted.