Chapter 11 — Network and communications security: assets and context

Chapter 11 — Network and communications security: assets and context

Lesson map

Lesson 11 published. Map, example, EX031.

flowchart TD
  N0["Learning outcomes"]
  N1["11.1 Network assets"]
  N2["11.2 Context and constraints"]
  N3["11.3 Stakeholders"]
  N4["11.4 Dependencies and suppliers"]
  N5["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> N5
  N5 --> EX["Worked example"]
  EX --> Q["Exercise EX031"]

Logical drawing

flowchart LR
  N0["Learning outcomes"]
  N1["11.1 Network assets"]
  N2["11.2 Context and constraints"]
  N3["11.3 Stakeholders"]
  N4["11.4 Dependencies and suppliers"]
  N5["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> Q["EX031"]

[Learning outcomes]
    |
    v
[11.1 Network assets]
    |
    v
[11.2 Context and constraints]
    |
    v
[11.3 Stakeholders]
    |
    v
[11.4 Dependencies and suppliers]
    |
    v
[Synthesis]
    |
    v
[Worked example] --> [Exercise EX031]

Learning outcomes

You will (1) identify network assets and owners; (2) understand school context and constraints; (3) record dependencies.

11.1 Network assets

Network assets include the devices that carry traffic, such as the gateway firewall, twelve switches and thirty wireless access points, and the services that make the network usable, such as DHCP, DNS and the wireless controller. Tomás adds these to the inventory with their locations, firmware versions and owners. He notes which are single points of failure: the core switch in the server room connects every building, so its failure would stop the whole school. Knowing which assets are critical helps decide where to spend effort on resilience as well as security.

11.2 Context and constraints

Every design must fit its context. Ridgeway has one technician, a small budget, a fixed school calendar and many users who are children. Teachers need technology to work at the start of every lesson; there is no time to troubleshoot during class. Changes are possible mainly in holidays. Safeguarding duties mean the school must filter harmful content for students and keep records of serious concerns. Tomás lists these constraints at the start of his design notes, because a design that ignores them will not be adopted or will fail in use.

11.3 Stakeholders

Several people care about the network for different reasons. The head teacher cares about safety, reputation and cost. Teachers care about reliability during lessons. The business manager cares about finance systems. The safeguarding lead cares about content filtering and reporting. Gareth cares about workload. Tomás meets each briefly to understand their needs. He finds that the business manager is unaware that student devices share a network with finance systems, and that once she understands, she becomes a strong supporter of separation.

11.4 Dependencies and suppliers

The school relies on suppliers: an internet provider, a filtering service, the learning platform, a managed print supplier and a heating control company with a remote connection. Tomás records each supplier's access: what they connect to, how and who authorises it. The heating company's connection goes directly into the main subnet through an old remote access tool. He flags it for review, recalling that forgotten supplier access is a common cause of incidents, and proposes routing it through a controlled path with named accounts.

Worked example

The asset list adds 43 network devices; the core switch is marked as a single point of failure, and the heating company's direct access is flagged.

Synthetic case. Assets and suppliers are synthetic.

Errors and limits

Designs that ignore the school calendar and staff capacity are rarely implemented as intended.

Exercises

• EX031 — Single point of failure. Which asset is a single point of failure, and why? Rubric: 3 = core switch connecting all buildings;; 2 = core switch;; 1 = firewall;; 0 = none.
• EX032 — Business manager response. Why did the business manager support separation? Rubric: 3 = learned finance shares network with students;; 2 = awareness;; 1 = cost;; 0 = none.
• EX033 — Supplier access fix. How should the heating company's access be changed? Rubric: 3 = controlled path with named accounts;; 2 = controlled;; 1 = removed;; 0 = none.

Synthesis

Knowing network assets, constraints, stakeholders and suppliers grounds design in the school's reality.

Continue studying — chapter 11 of 30

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