The Intermediate level:

Hardening

• Alternate password hashing
• SUID grouping
• Trusted daemon installation
• More diligent log monitoring
• Swatch
• Log filters
• Password Auditing
• Crack
• John the Ripper
• Reducing remote information
• Disable or modify fingerd
• Modify issue and issue.net
• tcpwrapper based filtering
• kernel based firewall
• ipfwadm
• ipchains