Wireless security breaks the traditional wired security model as wireless networks operate at unprotected lower layers compared to wired networks. Key threats to wireless networks include denial of service attacks, rogue access points, and common vulnerabilities across all layers that are typically protected on wired networks. Effective wireless security requires defenses at multiple layers including anti-virus software, firewalls, intrusion detection systems, and VPNs to protect against both external and internal threats on open wireless networks.