To prevent unauthorized users from connecting to the organization's wireless network, the best control among the provided options is NAC (Network Access Control).
NAC solutions are designed to enforce security policies on devices attempting to connect to a network, ensuring that only authorized and compliant devices gain access. This can include checking for proper authentication, security posture, and ensuring that devices meet certain criteria before granting them access to the network.
Here’s a brief overview of the other options for context:
- Segmentation: This helps control traffic within different network segments but does not specifically prevent unauthorized connections to a wireless network.
- IPS (Intrusion Prevention System): This is used to detect and prevent identified threats in real-time but does not handle access control directly.
- Firewall: Firewalls provide network perimeter security and can apply some access controls, but they are not typically focused on wireless access control in the way that NAC is.
Therefore, for Ken's specific requirement, NAC is the most appropriate choice.