What is device fingerprinting?
Device fingerprinting collects attributes about a device, its browser, or its network behavior. It combines them into a unique identifier that recognizes the same device over time.
It is used both to track users online and, inside organizations, to identify devices for security.
The approach is drawing fresh attention from regulators. From 16 February 2025 Google no longer prohibits advertisers from employing fingerprinting techniques. The UK Information Commissioner's Office said fingerprinting could now replace the functions of third-party cookies (UK ICO, December 2024).
How device fingerprinting works
A script or system gathers signals from a device and hashes them into a single identifier. There are two main families of techniques.
Browser or web fingerprinting reads attributes like the user agent, screen resolution, time zone, fonts, and canvas.
Network or device fingerprinting is used on managed networks. It relies on Dynamic Host Configuration Protocol (DHCP) fingerprinting, which reads distinguishing options in a device's DHCP request. It also uses the organizationally unique identifier (OUI) — the first six digits of the MAC address — which identifies the manufacturer.
These methods help networks spot devices that cannot announce themselves. A fingerprint is effective when it is persistent, meaning stable over time, and unique, meaning distinguishable from others.
Device fingerprinting vs. cookies
Cookies are small files stored on the device, so users can clear them at any time. A fingerprint is derived from device characteristics and stores nothing, so it cannot simply be deleted.
This persistence is one reason advertisers turn to fingerprinting as cookies are phased out.
Why enterprises use device fingerprinting
Beyond ad tracking, fingerprinting is a legitimate security control. Many Internet of Things (IoT) and operational technology (OT) devices cannot log in with a username and password.
Networks identify these devices by their fingerprint. This enables device profiling, segmentation, and access decisions.
- Key point: visibility. Fingerprinting reveals what is connecting to the network, where, and how.
- Key point: automated onboarding. Agentless devices are recognized and admitted without manual setup.
- Key point: segmentation. Each device is grouped and given only the access its role requires.
This matters at scale. The number of connected devices keeps climbing. Unmanaged devices are also a common attack path.
The Microsoft Digital Defense Report 2024 underscores the risk. Of those attacks that did progress to the ransom stage, over 90% used unmanaged devices as their initial access point or for remote encryption.
Cloudi-Fi addresses this with IoT fingerprinting and identity. Its Cloud DHCP fingerprinting analyzes device type, brand, operating system (OS), and MAC-address vendor.
It assigns each device to a security profile — whitelisted, blacklisted, or quarantined — aligned with Zero Trust approach
This extends network access control to devices that legacy tools miss. It is all delivered through a cloud DHCP service.
Frequently asked questions
Is device fingerprinting the same as browser fingerprinting?
Browser fingerprinting is one type that reads browser attributes. Device fingerprinting is broader and can include hardware and network signals such as DHCP behavior.
Can device fingerprinting be blocked?
It is harder to block than cookies because nothing is stored to delete. Privacy browsers and tracker-blocking tools reduce it but cannot fully eliminate it.
Is device fingerprinting legal?
It is widely used across the web and enterprise networks. Regulators such as the UK ICO treat it as personal-data processing that generally requires requires also explicit user consent in case of tracking.
