Chapter 4 — Network and communications security: guided lab and applied synthesis
Lesson map
Lesson 04 published. Map, example, EX039.
flowchart TD
N0["Learning outcomes"]
N1["4.1 The router checklist"]
N2["Lab — Router checklist"]
N3["4.2 Reading the checklist"]
N4["4.3 Making the changes"]
N5["4.4 Checking the result"]
N6["4.5 Habits for the future"]
N7["4.6 The short report"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> N6 --> N7
N7 --> EX["Worked example"]
EX --> Q["Exercise EX039"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["4.1 The router checklist"]
N2["Lab — Router checklist"]
N3["4.2 Reading the checklist"]
N4["4.3 Making the changes"]
N5["4.4 Checking the result"]
N6["4.5 Habits for the future"]
N7["4.6 The short report"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> N6 --> N7 --> Q["EX039"]
[Learning outcomes]
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[4.1 The router checklist]
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[Lab — Router checklist]
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[4.2 Reading the checklist]
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[4.3 Making the changes]
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v
[4.4 Checking the result]
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v
[4.5 Habits for the future]
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[4.6 The short report]
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v
[Worked example] --> [Exercise EX039]
Learning outcomes
You will (1) check router settings against a checklist; (2) make agreed changes safely; (3) write a short report.
4.1 The router checklist
Leo builds a short checklist for the bakery router based on common guidance: the administrator password changed from the factory default; Wi-Fi using WPA2 or WPA3 with a strong passphrase; a guest network for customers that is isolated from business devices; remote administration from the internet turned off; firmware updated recently; and UPnP turned off unless needed, because it lets devices open ports on the router automatically. Each item is easy to check in the router's settings pages and addresses a common weakness in small business networks.
Lab — Router checklist
"""Check a synthetic small-office router settings summary against a basic checklist (stdlib only)."""
settings = {"admin_password_changed": False, "wifi_security": "WPA2-Personal", "guest_network": True,
"guest_isolated_from_lan": False, "remote_admin": True, "firmware_age_days": 540, "upnp": True}
checks = [("admin password changed from default", settings["admin_password_changed"]),
("Wi-Fi uses WPA2 or WPA3", settings["wifi_security"] in ("WPA2-Personal", "WPA3-Personal")),
("guest network enabled", settings["guest_network"]),
("guest isolated from business devices", settings["guest_isolated_from_lan"]),
("remote administration off", not settings["remote_admin"]),
("firmware updated within 180 days", settings["firmware_age_days"] <= 180),
("UPnP off", not settings["upnp"])]
for name, ok in checks: print(f"{'PASS' if ok else 'FIX '} {name}")
print(f"{sum(ok for _, ok in checks)} of {len(checks)} pass")
Run with python3 lab_router.py. Verified output:
FIX admin password changed from default
PASS Wi-Fi uses WPA2 or WPA3
PASS guest network enabled
FIX guest isolated from business devices
FIX remote administration off
FIX firmware updated within 180 days
FIX UPnP off
2 of 7 pass
4.2 Reading the checklist
The synthetic settings pass only two of seven checks: Wi-Fi security and the existence of a guest network. The administrator password is still the default, the guest network is not isolated from business devices, remote administration is on, firmware is about eighteen months old and UPnP is on. Leo orders the fixes by value: change the administrator password first, because anyone who guesses it can change everything else; then isolate the guest network and turn off remote administration; then update firmware and turn off UPnP.
4.3 Making the changes
After closing, with Ellen present and approving each step, Leo changes the administrator password to a long passphrase that Ellen stores in a password manager. He turns on guest isolation and moves the smart speaker and scanner to the guest network. He turns off remote administration and UPnP. He updates the firmware using the router's built-in update function. After each change, he checks that tills, the card reader and the office computer still connect and that a test card payment works. He records every change with the original value.
4.4 Checking the result
Leo reruns the checklist against the new settings: seven of seven pass. He also tests guest isolation by connecting his own phone to the guest network and confirming it can reach the internet but not the office computer, with Ellen's permission and without trying anything beyond a simple connection check. The next morning, he calls Ellen to confirm opening went smoothly. Verifying results, not just making changes, is what shows the work actually achieved its goal. He saves the after-change checklist output with the date as evidence for the report.
4.5 Habits for the future
Leo leaves Ellen with a short list of habits: check the router's device list monthly; check for firmware updates every three months; change the guest Wi-Fi passphrase every few months and after staff leave; use a password manager and multi-factor authentication for email and the order platform; and call the internet provider or the payment company for problems with their equipment. These habits take little time but keep the improvements in place long after the course ends. He prints the list and pins it beside the office computer.
4.6 The short report
Leo's final report is two pages. It covers what he found, what was changed and why, the before and after checklist results, the remaining recommendations and the monthly habits. It uses plain language, avoids jargon and includes the record of changes. Nadia reviews it before Leo gives it to Ellen. A short, clear report lets Ellen understand her network, explain it to an adviser or insurer and pick up where Leo left off. Ellen keeps a printed copy with the router's documentation, and a digital copy in her cloud storage.
4.7 Reflection
Leo reflects that the biggest improvements came from simple steps: a changed password, guest isolation and turning off unneeded features. The most important skills were not technical: agreeing permission, working after hours, recording changes and stopping to ask about unknown devices. Nadia points out that these habits apply at any scale, from a bakery to a large organisation, and that the rest of the curriculum builds on exactly these foundations. He plans to take the technical course next, building on what he practised at the bakery.
Worked example
The router passes two of seven checks before changes and seven of seven after; Ellen receives a two-page report and five habits.
Synthetic case. Router settings are synthetic.
Errors and limits
Making several router changes at once during opening hours risks stopping card payments with no clear cause.
Exercises
- EX039 — Initial checklist result. How many checks pass before changes? Rubric: 3 = 2 of 7, Wi-Fi security and guest network exists;; 2 = two;; 1 = seven;; 0 = none.
- EX040 — First fix. Which fix comes first, and why? Rubric: 3 = admin password; controls everything else;; 2 = password;; 1 = firmware;; 0 = none.
- EX041 — UPnP reason. Why turn off UPnP? Rubric: 3 = lets devices open ports automatically;; 2 = ports;; 1 = speed;; 0 = none.
- EX042 — Guest isolation test. How is guest isolation tested? Rubric: 3 = phone on guest reaches internet not office PC, with permission;; 2 = test;; 1 = vague;; 0 = none.
- EX043 — Password storage. Where is the new router password stored? Rubric: 3 = Ellen's password manager;; 2 = manager;; 1 = note;; 0 = none.
- EX044 — After-change test. What is tested after each change? Rubric: 3 = tills, card reader, office PC and test payment;; 2 = payments;; 1 = vague;; 0 = none.
- EX045 — Final checklist. How many checks pass after changes? Rubric: 3 = 7 of 7;; 2 = all;; 1 = six;; 0 = none.
- EX046 — Firmware habit. How often should Ellen check for firmware updates? Rubric: 3 = every three months;; 2 = quarterly;; 1 = never;; 0 = none.
- EX047 — Guest passphrase habit. When should the guest passphrase change? Rubric: 3 = every few months and after staff leave;; 2 = periodically;; 1 = never;; 0 = none.
- EX048 — Report contents. List four parts of Leo's report. Rubric: 3 = findings, changes, before/after, recommendations or habits;; 2 = three;; 1 = fewer;; 0 = none.
- EX049 — Morning check. Why call Ellen the next morning? Rubric: 3 = confirm opening went smoothly;; 2 = verify;; 1 = courtesy;; 0 = none.
- EX050 — Key reflection. What did Leo find mattered most besides technical steps? Rubric: 3 = permission, timing, records, stopping to ask;; 2 = habits;; 1 = vague;; 0 = none.
Synthesis
A simple checklist, careful agreed changes, verification and clear habits secure a small business network quickly.
Continue studying — chapter 04 of 04
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