Remote Access and File Transfer

Protocol Overviews

Telnet (Telecommunication Network)

• Purpose: Provides unencrypted command-line access to remote devices.

• Port: TCP/23.

• Security: No encryption; credentials and data transmitted in plaintext.

• Use Cases: Legacy systems, internal networks (discouraged in modern environments).

SSH (Secure Shell)

• Purpose: Encrypted replacement for Telnet, enabling secure remote access and command execution.

• Port: TCP/22.

• Security: Strong encryption (AES, ChaCha20), authentication, and integrity checks.

• Use Cases: Secure server management, tunneling, automation.

FTP (File Transfer Protocol)

• Purpose: Transfers files between systems over a network.

• Ports: TCP/21 (control), TCP/20 (data).

• Security: No encryption; credentials and files sent in plaintext.

• Use Cases: Non-sensitive file sharing, legacy systems.

SFTP (SSH File Transfer Protocol)

• Purpose: Secure file transfer over an encrypted SSH connection.

• Port: TCP/22 (uses SSH).

• Security: Inherits SSH's encryption and authentication.

• Use Cases: Secure file transfers, compliance-driven environments.

Key Features Comparison

Feature	Telnet	SSH	FTP	SFTP
Encryption	None	AES, ChaCha20, etc.	None	AES, ChaCha20 (via SSH)
Authentication	Plaintext credentials	Public/private keys, passwords	Plaintext credentials	SSH keys, passwords
Data Integrity	No	Yes (HMAC)	No	Yes (via SSH)
Ports	23	22	20/21	22
Security Risks	High (sniffing, MITM attacks)	Low (if properly configured)	High (sniffing, data leaks)	Low (depends on SSH security)
Use Cases	Legacy device management (avoid in production)	Secure remote administration, scripting	Non-critical file transfers (internal use)	Secure file transfers, compliance (HIPAA, PCI-DSS)
Compliance	Non-compliant	Required for secure environments	Non-compliant	Required for secure environments

Summary of Use Cases

• Telnet:

  • Avoid in production. Only for legacy/internal systems with no security requirements.

• SSH:

  • Default for secure remote access, tunneling, and automation.

• FTP:

  • Suitable for non-sensitive transfers where simplicity is prioritized (e.g., local networks).

• SFTP:

  • Secure alternative to FTP; ideal for sensitive data, compliance, and encrypted transfers.

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Key Takeaways:

• Security: SSH/SFTP > FTP > Telnet.

• Encryption: SSH and SFTP encrypt all traffic; Telnet/FTP expose data.

• Compliance: SSH and SFTP meet modern standards; Telnet/FTP are obsolete for regulated use. Always prefer SSH/SFTP for secure operations. Use FTP only in isolated, non-sensitive environments.