When setting up file transfer capabilities for a web server, three main protocols come into play:

// Example FTP connection in Python
import ftplib
ftp = ftplib.FTP('hostname')
ftp.login('user', 'password')
ftp.cwd('/target_directory')
ftp.retrbinary('RETR filename', open('localfile', 'wb').write)
ftp.quit()

FTP transmits credentials and data in plaintext, making it vulnerable to sniffing attacks. Both SFTP and FTPS encrypt the entire session:

• SFTP (SSH File Transfer Protocol) runs over SSH (port 22)
• FTPS (FTP Secure) adds TLS/SSL encryption to FTP

SFTP is generally easier to implement as it uses a single port:

// SFTP connection using paramiko
import paramiko
transport = paramiko.Transport(('hostname', 22))
transport.connect(username='user', password='password')
sftp = paramiko.SFTPClient.from_transport(transport)
sftp.put('localfile', 'remotefile')
sftp.close()

FTPS requires managing certificates but maintains FTP compatibility:

// FTPS connection with explicit TLS
from ftplib import FTP_TLS
ftps = FTP_TLS('hostname')
ftps.login('user', 'password')
ftps.prot_p()  # Secure data connection
ftps.retrbinary('RETR filename', open('localfile', 'wb').write)
ftps.quit()

Traditional FTP uses multiple ports (21 for control, dynamic ports for data), creating firewall challenges. SFTP's single-port approach simplifies network configuration, especially in cloud environments.

In our benchmarks transferring 1GB files:

For occasional internet-accessible transfers where security is paramount, SFTP provides the best balance:

1. No certificate management overhead
2. Strong encryption via SSH
3. Simpler firewall configuration
4. Widely supported by clients

The choice ultimately depends on your specific environment and client requirements, but SFTP is generally the most secure and maintainable option for modern deployments.

When setting up file transfer capabilities for a web server exposed to the internet, the security implications become paramount. Let's break down the three main options:

// Typical FTP connection example (INSECURE)
ftp = FTP('ftp.example.com')
ftp.login('user', 'password')
ftp.upload('local_file.txt', 'remote_file.txt')

The fundamental difference lies in encryption:

• FTP: Cleartext transmission (port 21)
• SFTP: SSH encryption (port 22)
• FTPS: SSL/TLS encryption (ports 21/990)

For your use case of occasional secure transfers, here's a Python example using SFTP (paramiko library):

import paramiko

transport = paramiko.Transport(('sftp.example.com', 22))
transport.connect(username='user', password='password')
sftp = paramiko.SFTPClient.from_transport(transport)

sftp.put('local_file.txt', 'remote_file.txt')
sftp.close()
transport.close()

SFTP requires only port 22 (SSH) to be open, while FTPS often needs multiple ports:

# iptables rules for SFTP (single port)
iptables -A INPUT -p tcp --dport 22 -j ACCEPT

# FTPS requires more complex rules
iptables -A INPUT -p tcp --dport 990 -j ACCEPT  # Implicit TLS
iptables -A INPUT -p tcp --dport 21 -j ACCEPT   # Explicit TLS

In our stress tests (1GB file transfers):

For your requirements of occasional secure transfers with internet accessibility:

• SFTP is the clear winner due to:
• - Single-port simplicity
• - Strong encryption via SSH
• - Widespread client support
• - No certificate management overhead

Here's a complete SFTP server setup example using OpenSSH:

# Install OpenSSH server
sudo apt install openssh-server

# Configure SFTP-only access
Match Group sftpusers
    ChrootDirectory /var/sftp
    ForceCommand internal-sftp
    AllowTcpForwarding no
    X11Forwarding no

# Create SFTP user
sudo addgroup sftpusers
sudo useradd -G sftpusers -s /bin/false sftpuser
sudo mkdir -p /var/sftp/upload
sudo chown root:root /var/sftp
sudo chmod 755 /var/sftp
sudo chown sftpuser:sftpusers /var/sftp/upload