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Writer's pictureAdam Partis

MAC Randomization: What It Means for WiFi Networks

Lets shed light on the concept of MAC randomization and how it impacts WiFi connectivity. A MAC (Media Access Control) address is a unique identifier assigned to each device’s network interface, usually remaining constant to allow networks to recognize that device. However, with MAC randomization, this identifier changes periodically, making it more difficult to track a device's activity across different connections.


Recently, MAC randomization has gained attention due to the upcoming features in iOS 18 and macOS 15. Traditionally, MAC addresses have stayed consistent, but with the new rotation feature in iOS 18 and macOS 15, devices will change their MAC address periodically, which makes it harder to track activity across various networks.


How Does MAC Address Randomization Work?

MAC address randomization works by generating a new MAC address every time a device connects to a WiFi network. Some devices will randomize their MAC address each time they connect to a new network, while others will change their address periodically.


With the upcoming updates to iOS 18 and macOS 15, Apple is implementing this feature with a rotation schedule—devices will rotate their MAC address approximately every two weeks. The change particularly applies to public WiFi and networks with weaker security. The rotation can also happen sooner if a user manually chooses to “forget” a network.


Why is MAC Randomization Important?

The introduction of MAC randomization brings a boost to user privacy by making it more challenging for external entities to track a device across different networks. By randomizing MAC addresses, users can reduce their digital footprint and improve online anonymity. However, it also poses a challenge for users who prefer seamless connectivity to public WiFi networks, as reconnections may require additional authentication.


Pros and Cons of MAC Address Randomization

Pros:

  • Enhanced Privacy: MAC randomization makes it difficult for third parties to track users across different WiFi networks, adding a layer of privacy.

  • Protection on Public Networks: It offers protection against unwanted tracking when connecting to public WiFi networks.


Cons:

  • Impact on Network Analytics: MAC randomization may disrupt visitor behavior analytics, affecting metrics like visit duration and return frequency.

  • Reduced Targeting Capabilities: Marketers relying on MAC addresses for personalized messaging may find it harder to target users.

  • Potential Connectivity Issues: Devices may face issues connecting to networks that require a consistent MAC address for authentication or network services.


Effect on Secure Connections

While MAC randomization enhances privacy, it does not directly affect common security protocols such as HTTPS, which protect data transferred between devices and servers. However, some network security measures—such as MAC-based whitelisting—may be affected, potentially leading to additional authentication requirements each time the device reconnects.


Does MAC Randomization Improve Security?

MAC randomization generally improves privacy rather than security. It does not offer direct protection against malware, network attacks, or other common security threats. Instead, its main focus is to make device tracking more challenging.


Tracking Limitations of Randomized MAC Addresses

While MAC randomization makes tracking more difficult, it is not foolproof. There are still techniques that can identify and track devices despite randomized addresses, including:


  • Correlation Tracking: Devices connecting to the same networks repeatedly can still be identified by their behaviour, even if the MAC address changes.

  • Passive Fingerprinting: Devices can be tracked using other identifiers like signal strength, device type, and network behaviour, which can be analysed even when MAC addresses are randomized.


Upcoming Changes in iOS 18 and macOS 15

With iOS 18 and macOS 15, Apple is introducing more frequent MAC address rotation, which will occur approximately every two weeks or whenever a user manually forgets a network. These changes are expected to improve user privacy, but they also bring challenges for businesses relying on MAC-based analytics or seamless guest WiFi access.


Impact of MAC Randomization on Businesses

The increased frequency of MAC address changes with iOS 18 presents some potential challenges for businesses:

  • Reduced Accuracy of Analytics: Customer insights and loyalty programs that use MAC addresses may see less accurate data.

  • Challenges with Network Access Control: Security filtering processes and whitelisting may require updates to adapt to these changes.

  • Guest Access Issues: Returning visitors may face disruptions in automatic reconnection, particularly on public WiFi, as authentication will need to be repeated more frequently.


Preparing for MAC Address Rotation

As MAC randomization continues to evolve, particularly with the upcoming changes in iOS 18, it's important for businesses to prepare for these shifts. While challenges may arise for network administrators and hospitality providers, there are also opportunities to adapt and improve network privacy practices.


Watch Purple's recent webinar titled “iOS 18 Will Break Public WiFi Networks” where they discuss strategies for mitigating the impact of these updates.

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