Firewall settings

2.10 Apply Security Settings on SOHO Wireless and Wired Networks

📘CompTIA A+ Core 2 (220-1202)

A firewall is a security feature built into most SOHO routers and some operating systems. Its main job is to monitor, allow, or block network traffic based on security rules.

In a SOHO (Small Office/Home Office) network, the firewall usually runs on:

The router
Or a software firewall on a computer

For the CompTIA A+ exam, you must understand how firewall settings protect the network and how misconfigured firewall settings can create security risks.

This section focuses on two key firewall settings:

Disabling unused ports
Port forwarding / port mapping

1. Disabling Unused Ports

What Is a Port?

A port is a numbered communication endpoint used by network services and applications.

Examples:

Port 80 → Web traffic (HTTP)
Port 443 → Secure web traffic (HTTPS)
Port 22 → Secure remote access (SSH)
Port 3389 → Remote Desktop (RDP)

Each service listens on a specific port number.

Why Ports Matter for Security

If a port is open, it means:

A service is listening on that port
External or internal devices may be able to connect

Open but unused ports are a security risk because:

Attackers scan networks for open ports
Unused services may contain vulnerabilities
Malware can exploit open ports to gain access

What Does “Disabling Unused Ports” Mean?

Disabling unused ports means:

Blocking traffic on ports that are not required
Turning off unnecessary services
Closing ports at the firewall level

This is a basic but very important security practice.

How It Works on a SOHO Router

On a SOHO router firewall:

The router checks incoming and outgoing traffic
If traffic targets a blocked port, it is denied
If traffic targets an allowed port, it is permitted

By default:

Most SOHO routers block all inbound traffic
Outbound traffic is usually allowed

Exam-Relevant Points

For the CompTIA A+ exam, remember:

Unused ports should always be disabled
Open ports increase the attack surface
Disabling ports reduces:
- Unauthorized access
- Malware communication
- Network scanning attacks

Common Exam Scenarios

You may see questions like:

“A SOHO network has multiple open ports that are not in use. What should the technician do?”
- Correct answer: Disable or block unused ports on the firewall

Key Benefits of Disabling Unused Ports

Improves overall network security
Reduces exposure to attacks
Follows the principle of least privilege
Prevents unauthorized services from running

2. Port Forwarding / Port Mapping

What Is Port Forwarding?

Port forwarding (also called port mapping) is a firewall setting that:

Allows external traffic from the internet
To reach a specific internal device
On a specific port

It creates a rule that says:

“If traffic arrives on this port, send it to this internal system.”

Why Port Forwarding Exists

In a SOHO network:

Internal devices use private IP addresses
Private IPs are not reachable directly from the internet

Port forwarding allows:

External users
To access an internal service securely and intentionally

How Port Forwarding Works (Step-by-Step)

Traffic arrives at the router’s public IP
The firewall checks port forwarding rules
If a rule exists:
- Traffic is sent to the specified internal IP and port
If no rule exists:
- Traffic is blocked

IT-Based Example (No Analogies)

A server inside the network runs a service on port 443
The router forwards port 443 traffic
To the internal server’s private IP
External users can now access that service

This is intentional access, not accidental exposure.

Security Risks of Port Forwarding

Port forwarding opens holes in the firewall, which creates risk if not managed correctly.

Risks include:

Unauthorized access
Brute-force attacks
Exploitation of vulnerable services

Best Practices (Exam Important)

For the exam, always remember:

Only forward necessary ports
Avoid forwarding:
- Unused ports
- Administrative ports unless required
Remove port forwarding rules when no longer needed

Port Forwarding vs Disabling Ports (Key Difference)

Feature	Disabling Unused Ports	Port Forwarding
Purpose	Improve security	Allow external access
Default action	Block traffic	Allow traffic
Risk level	Low	Higher
Exam focus	Security best practice	Controlled access

Common Exam Scenarios

You may see questions like:

“An internal service needs to be accessible from the internet. What firewall feature should be configured?”
- Correct answer: Port forwarding
“A SOHO router has unnecessary port forwarding rules. What should be done?”
- Correct answer: Remove unused port forwarding rules

Key Exam Takeaways (Must Remember)

Disabling Unused Ports

Blocks unnecessary network traffic
Reduces attack surface
Prevents exploitation of unused services
Always recommended for SOHO security

Port Forwarding / Mapping

Allows external access to internal services
Requires careful configuration
Should only be used when absolutely necessary
Increases security risk if misconfigured

Summary for Students

A firewall controls network traffic
Closed ports = safer network
Open ports = higher risk
Port forwarding is powerful but dangerous if misused
Always follow the principle: Allow only what is required