What is FTP? File Transfer Protocol Explained.

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TL;DR: FTP (File Transfer Protocol) is a decades-old standard protocol that enables file transfers between a client and remote server using port 21 for commands and port 20 for data. While FTP remains widely used due to free FTP client software and straightforward operation, standard FTP transmits data without encryption, creating serious security vulnerabilities. Organizations requiring secure file transfers have evolved to SFTP (SSH File Transfer Protocol operating over port 22), FTPS (FTP with SSL/TLS encryption), or modern high-speed alternatives like IBM Aspera. Understanding how FTP works, its security limitations, and available secure alternatives empowers organizations to make informed decisions about protecting sensitive data during transfers across firewalls and networks.

FTP (File Transfer Protocol) is one of the earliest protocols designed to transfer files between computers using the TCP/IP suite. It follows a client-server model, where an FTP client connects to an FTP server to download or upload files. FTP uses two separate connections: a command channel for control signals and a data channel for transferring files.

Although foundational, FTP lacks encryption and is considered insecure by today’s standards. Organizations requiring fast, scalable, and secure file transfers are increasingly turning to modern alternatives like IBM Aspera, which provides encrypted, high-speed data movement via the FASP protocol.

What is an FTP?

FTP, or File Transfer Protocol, is an application layer protocol used for transferring files between a client and a server. One of the oldest protocols, it allows users to sign in and access files like data, videos, pictures, and other content. An FTP server offers access to a directory with subdirectories. Users connect to these servers with an FTP client, which lets you download and upload files from the server. 

FTP is one of the simplest and earliest mechanisms created to move files from one place to another. It uses two basic channels to operate: the command channel and data channel. The command channel carries information about the task itself, while the data channel transfers the actual file between devices.

What is an FTP Server?

An FTP server is a remote system that stores files and makes them accessible to users via FTP. It listens for connection requests from clients and enables file sharing using the client-server model. Once a connection is established, files can be uploaded or downloaded through designated command and data channels.

FTP servers support different authentication methods:

• User-authenticated FTP: Requires login credentials to access secure files
• Anonymous FTP: Allows users to access public files without credentials

Despite their flexibility, traditional FTP servers do not offer encryption, which exposes sensitive data to interception.

FTP vs. Secure File Transfer Protocols: Understanding Your Options

Feature	Standard FTP	FTPS	SFTP	IBM Aspera FASP
Stands For	File Transfer Protocol	FTP Secure	SSH File Transfer Protocol	Fast, Adaptive, and Secure Protocol
Port Numbers	Port 21 (command), Port 20 (data)	Port 21 + dynamic ports	Port 22 (uses SSH)	Configurable UDP ports
Encryption	None – unencrypted	SSL/TLS encryption	Secure Shell (SSH) encryption	Built-in AES encryption
Authentication	Username/password in plaintext	Encrypted credentials	SSH key-based or password	Token-based secure authentication
FTP Connection Type	Two separate connections	Two connections + SSL/TLS	Single SSH connection	Single optimized connection
Firewall Compatibility	Complex – requires multiple port openings	Very complex – dynamic ports problematic	Simple – single port (22)	Simplified – configurable ports
Free FTP Client Options	FileZilla, WinSCP, CyberDuck	FileZilla Pro, WinSCP	WinSCP, CyberDuck, command line	Aspera client software
How Does FTP Work?	Client-server model, command/data channels	Same as FTP + encryption layer	Secure shell protocol with file transfer	UDP-based with reliability layer
Speed Over Distance	Degraded by latency	Degraded by latency	Degraded by latency	Consistent – up to 1000x faster
Security Level	Insecure	Moderately secure	Secure	Highly secure
Remote Server Access	Direct, unencrypted	Encrypted connections	Encrypted via SSH	Encrypted with adaptive rate control
Enterprise Suitability	Not recommended	Limited use cases	Standard for secure transfers	Ideal for large-scale operations
FTP Support Legacy	Universal	Good	Excellent	Modern standard

Why This Matters: While standard FTP established the foundation for file transfers, modern security requirements and performance demands necessitate encrypted alternatives. SFTP leverages secure shell protocols to protect data, FTPS adds SSL/TLS encryption to traditional FTP, but only IBM Aspera combines enterprise-grade security with speeds that fully utilize available bandwidth regardless of distance or network conditions.

Disadvantages of Using FTP

Platforms that still offer FTP downloads or support transfers do so out of habit, but it has become less common. Unfortunately, with today’s business standards and the need to transfer files fast across the globe, FTP cannot scale to support the needs like any-to-any data transfers, large file ingestion, and cloud-native transfer. 

Most importantly, it is not a secured protocol. Developed before cybersecurity was more than a hypothetical field, the transfer is not encrypted, making it relatively easy to intercept files for hackers. 

Alternative Solutions for FTP: IBM Aspera

Using its proprietary FASP technology to deliver data, IBM Aspera software eliminates bottlenecks and risks associated with the outdated FTP technology. It can move files at maximum speeds, utilizing the available bandwidth. 

Using its adaptive rate control, it delivers higher performance than FTP without impacting other crucial business traffic. Even during periods of extreme network congestion, the rate control makes sure there is a timely acquisition and distribution of high-priority files.

Included with Aspera, their patented protocol offers built-in security for data transfers using the standard open-source OpenSSL toolkit. It also provides secure authentication of the transfer endpoints, on-the-fly encryption, and integrity verification for each transmitted datagram.

Essential Understanding: FTP and Secure File Transfer Evolution

FTP Fundamentals

• FTP stands for File Transfer Protocol, one of the earliest methods for transferring files between client software and a remote server
• Standard FTP uses port 21 for command communications and port 20 for data transfer, operating through separate command and data channels
• The FTP protocol follows a client-server model where users connect via an FTP client to access directories and subdirectories on the remote server
• Free FTP clients like FileZilla, WinSCP, and CyberDuck make it easy to use an FTP client for basic file transfers

How FTP Works and Its Limitations

• FTP connections require both command and data channels to establish a connection and transfer files
• The protocol transmits all data, including login credentials, without encryption, exposing sensitive information to interception
• Firewall configurations become complex with standard FTP due to multiple port requirements and dynamic port assignments
• FTP work is significantly slower than modern alternatives, especially across long distances or high-latency networks

Secure FTP Alternatives

• SFTP (SSH File Transfer Protocol) operates over port 22 using secure shell encryption, protecting data during transit
• FTPS adds SSL/TLS encryption to traditional FTP, maintaining FTP support while improving security
• Both SFTP and FTPS address standard FTP’s encryption vulnerabilities but inherit the same performance limitations
• Organizations can use port-forwarding through firewalls more easily with SFTP’s single-port architecture compared to FTP’s multiple-port complexity

Modern High-Speed Secure Transfer

• IBM Aspera’s FASP technology eliminates both the security and performance weaknesses inherent in FTP-based protocols
• Unlike standard FTP or even SFTP, Aspera delivers consistent throughput regardless of network latency or distance
• The ftp connection model established decades ago cannot scale to meet contemporary demands for secure, high-speed global data transfers
• Organizations requiring FTP support for legacy systems can implement Aspera alongside existing infrastructure for optimal flexibility

Security and Compliance Considerations

• Standard FTP transmits files without authentication protection, making it unsuitable for sensitive data or regulated industries
• Modern cybersecurity standards require encrypted file transfers, eliminating standard FTP from compliant workflows
• SSH file transfer protocol (SFTP) provides minimum acceptable security for most organizational requirements
• Enterprise-scale operations benefit from Aspera’s combination of military-grade encryption with breakthrough transfer speeds

Decision Framework for Your Organization

• Use SFTP when replacing legacy FTP systems requiring basic security improvements with minimal infrastructure changes
• Consider FTPS when existing FTP workflows must be secured but client software cannot support SSH protocols
• Choose IBM Aspera when transfer speed, distance, file size, or volume demands exceed what traditional file transfer protocols can efficiently deliver
• Consult PacGenesis to evaluate which secure file transfer protocol best aligns with your organization’s specific requirements, compliance obligations, and performance expectations

The evolution from standard FTP through SFTP and FTPS to modern solutions like IBM Aspera reflects the changing demands enterprises face. While FTP established the foundational concepts of client-server file transfer, contemporary organizations require both the security that FTP protocol lacks and the performance that distance-limited TCP-based solutions cannot deliver.

IBM Aspera with PacGenesis

IBM Aspera allows you to securely transfer data anywhere. With its complete portfolio of software products and technologies, it provides any organization from a wide variety of industries with the highest level of performance for every file transfer and use case. As an IBM Gold Business Partner, PacGenesis can help your business focus on scalable data transfer and workflow solutions for their needs. To better identify your high-speed transfer needs and set up an evaluation, contact us today. 
To learn more about PacGenesis, follow @PacGenesis on Facebook, Twitter, and LinkedIn or contact us at pacgenesis.com.

Data Transfer Tools/Network Performance Calculators

• File Transfer Calculator (Aspera)
• Network Throughput Calculator
• Download Time Calculator
• Upload Time Calculator
• Transfer Speed Calculator

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