Transferring sensitive data securely has become critical in the modern digital landscape. Organizations across various industries increasingly handle confidential and regulated information, making the secure transfer of data not just a preference but a necessity. Among various secure file transfer protocols, SFTP (Secure Shell File Transfer Protocol) has emerged as one of the most reliable and secure methods available today. This comprehensive guide aims to thoroughly explore what SFTP is, why it has become widely adopted, and particularly answer the question: what port does SFTP use?

What is SFTP?

SFTP, or Secure File Transfer Protocol, leverages SSH (Secure Shell) to transfer files securely over a network. Unlike traditional FTP, which transmits credentials and data in plaintext, SFTP encrypts all data and authentication details during the transfer process. This encryption ensures sensitive information remains confidential and secure from interception by malicious actors. Furthermore, SFTP consolidates command and data transfers through a single channel, significantly simplifying network management and firewall configuration.

Understanding Ports and Their Importance

Ports are essential in networking as they serve as logical endpoints for communication between devices. They allow multiple network applications to share a single network interface without conflict. Each port is identified by a number between 0 and 65,535, and many ports are reserved for common services, such as HTTP (port 80), HTTPS (port 443), and FTP (port 21).

For SFTP, understanding the port configuration is vital as it directly impacts firewall settings, network accessibility, and security posture. Incorrectly configured ports can expose sensitive data to unauthorized access, leading to potential data breaches or regulatory violations.

What is Port 22?

The default port number for SFTP is port 22, which is the standard port used by SSH. Since SFTP operates through SSH, it naturally inherits this port. This simplifies configuration, ensures compatibility with most firewalls, and leverages existing SSH infrastructure.

The choice of port 22 provides significant advantages:

• Encryption by default: All SFTP communications over port 22 are encrypted.
• Simplified firewall management: A single port simplifies firewall rules, reducing administrative overhead.
• Standardization: Widely recognized as secure and industry-standard, minimizing compatibility issues across different network environments.

Comparison of FTP, FTPS, and SFTP

Understanding the differences between FTP, FTPS, and SFTP is essential when deciding which protocol to adopt:

Protocol	Default Port(s)	Encryption	Complexity	Security
FTP	21 (commands), dynamic ports	None	Low	Poor, data is plaintext
FTPS	Ports 21 (explicit), 990	SSL/TLS	Moderate	Secure but complicated
SFTP	Port 22	SSH	Simple	Highly secure

SFTP emerges as the superior choice for its straightforward implementation, robust encryption, and firewall-friendly single-port operation.

Default SFTP Port (Port 22) Explained

Port 22 is the default because SFTP was built to work securely over the SSH protocol, which was originally designed to provide secure remote logins and command execution. This alignment ensures SFTP integrates seamlessly into existing security models, firewall rules, and administrative practices.

Benefits of Using Default Port 22

• Simplifies firewall management since administrators typically open and monitor fewer ports.
• Offers compatibility with common administrative tools and software.
• Ensures that data transfer is encrypted and authenticated seamlessly through SSH.

Changing the SFTP Port: Pros and Cons

Pros of Changing the SFTP Port Number

• Security Through Obscurity: Changing the port reduces automated attacks that specifically target port 22.
• Policy Compliance: Some organizations have internal security policies requiring alternative ports.

Cons of Changing the Default Port

• Minimal Actual Security Improvement: Changing the port number doesn’t significantly deter determined attackers who perform port scans.
• Complexity: Non-standard ports require additional configuration and documentation.
• Troubleshooting Difficulty: Administrators and users accustomed to port 22 might face confusion.

Common Firewall Considerations

Ensuring the SFTP port is correctly configured in your firewall is crucial for secure operations:

• Open port 22 on inbound firewalls to permit external access.
• Confirm outbound port 22 is open for clients behind restrictive firewalls.
• Regularly audit firewall rules to prevent unauthorized access and close unnecessary ports.

How to Open SFTP Port 22

On Windows (Windows Defender Firewall)

1. Open the Windows Defender Firewall settings.
2. Navigate to Inbound Rules and create a new rule for TCP Port 22.
3. Allow connections and apply rules across necessary network profiles.

Linux (firewalld)

Run the following commands:

sudo firewall-cmd –add-port=22/tcp –permanent

sudo firewall-cmd –reload

Verify the configuration:

sudo netstat -tlnp | grep 22

Securing Your SFTP Port Configuration

Simply opening port 22 for SFTP isn’t sufficient for optimal security. Consider these best practices:

• Key-based Authentication: Prefer SSH key pairs over password authentication.
• Disable Root Logins: Prohibit direct root access to limit risk.
• IP Whitelisting: Allow connections only from trusted IP addresses.
• Regular Updates: Ensure SSH software and OS patches are consistently updated.
• Multi-Factor Authentication: Implement additional authentication steps for heightened security.
• Regular Audits and Monitoring: Continuously monitor SFTP access logs and review regularly.

Real-world Scenarios and Recommendations

Enterprise Environment

In large enterprises, maintaining port 22 is often advisable for ease of management and standardization. Security should focus on multi-factor authentication, comprehensive logging, and regular vulnerability assessments.

Small Business and SMBs

Small businesses might benefit from changing the default port to reduce automated scanning attempts, though this should always be coupled with strong authentication mechanisms and firewall rules.

Regulatory Compliance

For industries governed by strict compliance frameworks (HIPAA, GDPR, PCI-DSS), using port 22 is generally preferred, combined with additional protective layers like encryption, audit trails, and Data Loss Prevention (DLP) integrations.

Conclusion and Final Thoughts

To answer definitively, port 22 is the default and recommended port for SFTP because of its compatibility, security via SSH, and ease of firewall management. While alternative ports can be used to slightly reduce automated threats, robust security primarily arises from employing strong authentication methods, regular updates, stringent access controls, and vigilant monitoring practices.

By adhering to best practices, organizations can securely transfer files while minimizing risks, safeguarding data integrity, and maintaining compliance with regulatory standards. As technology evolves, continuous evaluation and adaptation of security measures remain essential for protecting sensitive information effectively.