FTP (File Transfer Protocol) is a standard network protocol used for transferring files between a client and server on a computer network. This playbook outlines key aspects of FTP security, testing procedures, and best practices.

FTP Basics

• Port Information:
  • Control Connection: Port 21
  • Data Transfer: Port 20

Security Assessment Tools

Nmap

Nmap is a powerful network scanning and discovery tool. Here are some useful Nmap commands for FTP security assessment:

sudo nmap -sV -p21 -sC -A <target_ip>

This command performs:

• Service/version detection (-sV)
• Scans port 21 (-p21)
• Runs default scripts (-sC)
• Enables OS detection, version scanning, script scanning, and traceroute (-A)

For more detailed output:

sudo nmap -sV -p21 -sC -A <target_ip> --script-trace

Other Useful Tools

• Netcat: For basic connection testing

nc -nv <target_ip> 21

• Telnet: For interactive sessions

telnet <target_ip> 21

• OpenSSL: For testing FTPS (FTP over SSL/TLS)

openssl s_client -connect <target_ip>:21 -starttls ftp

FTP Enumeration and Exploitation

1. Anonymous Access:
   Test for anonymous FTP access:

ftp <target_ip>

Use “anonymous” as username and password.

2. Recursive Download:
   If anonymous access is allowed, attempt to download all accessible files:

wget -m --no-passive ftp://anonymous:anonymous@<target_ip>

3. File Structure Analysis:
   After downloading, analyse the file structure.

tree .

Best Practices

1. Restrict FTP Access:
   • Regularly review and update /etc/ftpusers file to restrict FTP access for sensitive accounts.
2. Use Secure Alternatives:
   • Consider using SFTP (SSH File Transfer Protocol) or FTPS (FTP over SSL/TLS) instead of plain FTP.
3. Regular Security Audits:
   • Perform regular security scans and penetration tests on FTP servers.
4. Keep Tools Updated:
   • Regularly update security tools. For Nmap:

sudo nmap --script-updatedb

Conclusion

This playbook provides a structured approach to FTP security assessment and best practices. Regular updates and adherence to these guidelines will help maintain a secure FTP environment. Always ensure that penetration testing is conducted ethically and with proper authorisation.