Zero Trust Network

Notes on the book Zero Trust Network.

Zero Trust Fundamentals

Zero trust aims to solve the inherent problems in placing our trust in the network. Instead, it is possible to secure network communication and access so effectively that physical security of the transport layer can be reasonably disregarded. It goes without saying that this is a lofty goal. The good news is that we’ve got pretty good crypto these days, and given the right automation systems, this vision is actually attainable.

A zero trust network is built upon five fundamental assertions:

Traditional approach(perimeter model): break networks into zones, different level of trust by zone.

If we instead declare that network location has no value, VPN is suddenly rendered obsolete.

Zero Trust Control Plane

Requests for access to protected resources are first made through the control plane, where both the device and user must be authenticated and authorized.

Once the control plane has decided that the request will be allowed, it dynamically configures the data plane to accept traffic from that client (and that client only).

The zero trust model dictates that all hosts be treated as if they’re internet-facing. The networks they reside in must be considered compromised and hostile.

Managing Trust

Trust management is the most important component of a zero trust network.

Define threat model. The Internet environment has a fairly well understood threat model. In general, we assume that the end-systems engaging in a protocol exchange have not themselves been compromised. By contrast, we assume that the attacker has nearly complete control of the communications channel over which the end-systems communicate.

Zero trust needs

Network Agents

network agent = user x device

A network agent as an ephemeral entity that is formed on demand to evaluate a policy. The data that is used to form an agent — user or device information — will typically be stored in persistent storage and queried to form an agent. When this data is queried, the union of the data at that point in time is what we call an agent.

No existing standards.

Making Authorization Decisions

Trusting User/Device/Application/Traffic…


Realizing a Zero Trust Network


Zero trust proxies are application-level proxy servers which can be used to secure a zero trust network. Proxies are deployed as infrastructure to handle authentication, authorization, and encryption responsibilities.

Adversarial View


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