Chapter 10 — Network and communications security: orientation | Technologist Network and communications security

Open, free learning for anyone who wants to protect people and technology. No account is required to read this text or its worked answers.

Lesson map

Lesson 10 published. Map, example, EX028.

flowchart TD
  N0["Learning outcomes"]
  N1["10.1 What the field covers"]
  N2["10.2 From perimeter to internal controls"]
  N3["10.3 Placement plan"]
  N4["10.4 Agreement and boundaries"]
  N5["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> N5
  N5 --> EX["Worked example"]
  EX --> Q["Exercise EX028"]

Logical drawing

flowchart LR
  N0["Learning outcomes"]
  N1["10.1 What the field covers"]
  N2["10.2 From perimeter to internal controls"]
  N3["10.3 Placement plan"]
  N4["10.4 Agreement and boundaries"]
  N5["Synthesis"]
  N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> Q["EX028"]

[Learning outcomes]
    |
    v
[10.1 What the field covers]
    |
    v
[10.2 From perimeter to internal controls]
    |
    v
[10.3 Placement plan]
    |
    v
[10.4 Agreement and boundaries]
    |
    v
[Synthesis]
    |
    v
[Worked example] --> [Exercise EX028]

Learning outcomes

You will (1) describe the field's scope; (2) relate it to the school; (3) plan the placement.

10.1 What the field covers

Network and communications security protects data in transit and the networks that carry it. It includes segmentation and firewalls, secure protocols such as TLS and SSH, wireless security, DNS protection, monitoring and detection, and the operational processes that keep controls working. Tomás maps each area to the school: segmentation addresses the flat network, secure protocols address Telnet on switches, wireless security addresses the shared passphrase, DNS filtering already protects students, and monitoring is mostly missing. This map shows where the placement should start.

10.2 From perimeter to internal controls

The school's current design trusts everything inside and filters only at the internet gateway. Modern guidance, including NIST SP 800-207 on zero trust architecture, argues that internal traffic deserves the same scrutiny as external traffic, because once an attacker or curious user is inside, a flat network offers no further resistance. Tomás does not propose full zero trust for a school with one technician, but he adopts its central idea: reduce implicit trust between groups and check access more carefully at internal boundaries.

10.3 Placement plan

Tomás and Gareth agree a placement plan for the coming terms. First, complete the inventory and risk list. Second, design zones and needed flows. Third, test in a lab. Fourth, implement in stages during school holidays. Fifth, introduce monitoring and routines. Each stage has a deliverable and a review with Ms Okafor. The plan respects the school's calendar, avoiding exam periods for any change. A written plan helps everyone know what to expect and when decisions are needed. Dates are shared with school leaders.

10.4 Agreement and boundaries

The placement agreement, signed by the head teacher, Ms Okafor and Tomás, states what he may do: review configurations and logs provided by Gareth, build lab copies, and assist Gareth with changes Gareth approves. He may not make changes alone, access student data or run tools against the school network without Gareth's explicit approval for each activity. Clear boundaries protect the school, the college and Tomás, and they are a normal part of professional practice in network security. Copies are kept by all three parties.

Worked example

The placement plan has five stages, each with a deliverable and a review date, avoiding exam periods.

Synthetic case. The plan is synthetic.

Errors and limits

Starting technical work before agreeing boundaries risks well-meant actions that breach trust or law.

Exercises

EX028 — Zero trust idea adopted. Which zero trust idea does Tomás adopt for the school?
Show marking criteria
Rubric: 3 = reduce implicit trust between internal groups;; 2 = internal checks;; 1 = full zero trust;; 0 = none.
EX029 — Exam periods. Why does the placement plan avoid exam periods?
Show marking criteria
Rubric: 3 = changes could disrupt exams;; 2 = disruption;; 1 = holidays;; 0 = none.
EX030 — Placement boundary. Name one activity Tomás may not do alone.
Show marking criteria
Rubric: 3 = make changes, access student data or run tools without approval;; 2 = one;; 1 = vague;; 0 = none.

Synthesis

Understanding the field's scope and agreeing a careful plan and boundaries prepare a safe placement.

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