Windows SharePoint Services Security Model Fundamentals

MOSS has a robust security model that provides management capabilities for controlling how MOSS is configured in a network, controlling how users access web applications, and controlling user access to content within web applications. The security model integrates seamlessly with:  

Microsoft Windows SharePoint Services takes advantage of the following elements that interact with and affect your security for Web site content:

• User authentication  
• SharePoint administrators group 
• Site groups 
• Administrative port security
• Microsoft SQL Server computer connection security
• Firewall protection  

Fore more details please visit Microsoft Official Website: Windows SharePoint Services Security Model