← ACARA Digital Technologies Years 9–10

Explaining how hardware and software control access to data in a network

Hardware like routers and firewalls moves and filters a request; software like protocols, login, permissions and encryption decides who may see the data and keeps it safe.

Part of: ACARA Digital Technologies Years 9–10 — Networked Systems and Access Control — Module 149, WA Computer Science ATAR Year 11 — Network Communications — Module 137, WA Computer Science ATAR Year 11 — Cyber Security — Module 139

Understanding Explaining how hardware and software control access to data in a network in ACARA Digital Technologies Years 9–10

What it does: Encrypting data into ciphertext protects confidentiality while the request crosses the network. The firewall is hardware or software that filters requests. This rule helps protect availability by blocking unwanted traffic. Logging in proves identity (authentication). Authorisation comes after, when permissions decide what you can access. Permissions such as read, write and execute are software controls in the operating system. A switch only forwards frames to devices on the LAN. Encryption keeps data private in transit. Plaintext could be read by anyone who intercepts it. If the hash matches, the file has not been altered. Availability is about the system being up when needed.

Common mistakes: A firewall filters traffic by its rules. It does not encrypt it. Encryption is done by protocols such as HTTPS. Line 3 should be: firewall FILTERS the packets. If the hash matches, the user has proved who they are, so the server should allow access. Denying a correct login would harm availability. It should be: IF match THEN ALLOW access.

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Learning
Duo
A student logs in to the school file server from a laptop. Which device first forwards the request towards the server?
A router, which uses its routing table to pick the next hopAn antivirus program, which chooses the route for each packet
Matches
Step 1: login | Device: switch checks the password
↓
A switch only forwards data inside a LAN. It does not check passwords. The server's authentication software checks the password.
Applying
Meanings
Term
access control
Meaning
Hardware like routers and firewalls moves and filters a request; software like protocols, login, permissions and encryption decides who may see the data and keeps it safe.
Practice
SEND login request from laptop
Testing
Gaps
2 : forwards data to other networks
Check Answer
Spots
2router FORWARDS packets
3firewall ENCRYPTS the packets

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Quick Questions

1. A student logs in to the school file server from a laptop. Which device first forwards the request towards the server?
A. An antivirus program, which chooses the route for each packet
B. A router, which uses its routing table to pick the next hop ✓
Routers are hardware that forward packets. Antivirus is software that scans for malware and does not route traffic.
2. Which is the best description of what a firewall does to a login request?
A. It checks the password and decides which files the user may open
B. It filters the request using rules, such as allow or deny by port or IP address ✓
A firewall filters traffic with rules. Checking passwords is authentication and deciding file access is authorisation, which software on the server does.
3. The server asks for a username and password. Which job is this?
A. Authentication: proving who you are ✓
B. Authorisation: deciding what you may do
Logging in proves identity (authentication). Authorisation comes after, when permissions decide what you can access.
4. After login, Mia can read a Year 10 folder but cannot change it. What controls this?
A. User permissions set by the operating system (read-only access) ✓
B. The network switch, which hides the files from her
Permissions such as read, write and execute are software controls in the operating system. A switch only forwards frames to devices on the LAN.
5. Which step protects confidentiality while the login travels across a public network?
A. Encryption with HTTPS or a VPN, so an eavesdropper only sees ciphertext ✓
B. Sending the password as plaintext so the server can read it faster
Encryption keeps data private in transit. Plaintext could be read by anyone who intercepts it.

Match the Pairs

router -> firewall -> file server → The path a login request takes: the router moves it, the firewall filters it, and the server receives it.
login(user, password) -> permissions check → Software first proves who you are, then decides which files you may read or change.
Encryption keeps data confidential while it travels, so anyone who intercepts it cannot read it. → HTTPS: encrypt(data, key) -> ciphertext
A firewall rule can filter a request by port, so only expected traffic reaches the file server. → firewall: allow port 445 from LAN, deny all
Step 1: login | Device: switch checks the password → A switch only forwards data inside a LAN. It does not check passwords. The server's authentication software checks the password.
firewall: allow all, then deny none | Goal: confidentiality → Allowing all traffic and denying none filters nothing, so unauthorised users can reach the data. Rules should allow only what is needed and deny the rest.

Key Term

access control
Hardware like routers and firewalls moves and filters a request; software like protocols, login, permissions and encryption decides who may see the data and keeps it safe.

Fill in the Blanks

1. 1 switch: connects devices on the LAN 2 router: forwards data to other networks 3 firewall: filters data by rules
Hint: Type the device that forwards a request on to other networks.
2. 1 user types username and password 2 server checks identity: authentication 3 then it checks permissions
Hint: Type the word for proving who you are.
3. r = read, w = write, x = execute student permission: r-- student can only read the file
Hint: Type the action that the r permission allows.
4. data in transit is encrypted with HTTPS eavesdroppers cannot read the data CIA goal kept: confidentiality
Hint: Type the security goal about keeping data from people who should not see it.
5. allow port 443 (HTTPS) allow port 445 (file server) default: deny everything else
Hint: Type the firewall action used for all traffic that has no allow rule.

Spot the Error

Question 1
A laptop SENDS login request
B router FORWARDS packets
C firewall ENCRYPTS the packets
D server CHECKS password hash
Line C — A firewall filters traffic by its rules. It does not encrypt it. Encryption is done by protocols such as HTTPS. Line 3 should be: firewall FILTERS the packets.
Question 2
A user ENTERS name and password
B HTTPS ENCRYPTS the login
C server COMPARES password hash
D IF match THEN DENY access
Line D — If the hash matches, the user has proved who they are, so the server should allow access. Denying a correct login would harm availability. It should be: IF match THEN ALLOW access.
Question 3
A login OK: user is student
B AUTHENTICATE: check permission
C student may READ only
D write request is DENIED
Line B — Authentication proves who you are, and the login already did that. Checking what the user may do is authorisation. It should be: AUTHORISE: check permission.
Question 4
A encryption -> confidentiality
B hash check -> availability
C backup server -> availability
Line B — A hash check shows whether data was changed, so it protects integrity. Availability is about keeping the system working, for example with a backup server. It should be: hash check -> integrity.
Question 5
A protocol <- HTTP
B port <- 443
C SEND login USING protocol
Line A — Port 443 is used by HTTPS, which encrypts the login so others cannot read it (confidentiality). Plain HTTP sends data as readable text. It should be: protocol <- HTTPS.

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