Learn how network defences — firewalls, VLANs, VPNs, and intrusion detection — work together to protect your organisation.
Network Security Fundamentals
Understanding how your organisation’s network is structured — and how attackers move through it — helps you recognise threats and apply the right protections.
Network Segmentation
Network segmentation divides a network into isolated zones (VLANs). If a device in the Guest VLAN is compromised, the attacker cannot directly reach the Servers VLAN — they would need to cross a firewall boundary first.
✓ Key Point
Why segmentation matters for you: If your workstation is compromised through a phishing email and your network has no segmentation, the attacker can potentially reach every device on the network — including file servers, domain controllers, and backup systems. Segmentation limits the blast radius.
Firewall Basics
A firewall filters network traffic based on rules. The principle of default deny means all traffic is blocked unless there is an explicit rule to allow it.
| Firewall Rule Type | Effect |
|---|---|
| Allow inbound TCP 443 (HTTPS) | Web traffic can reach the web server |
| Allow outbound TCP 80, 443 | Staff can browse the web |
| Deny all inbound | Block everything not explicitly permitted |
| Block outbound to known malware IPs | Prevent malware calling home (C2) |
Detecting Suspicious Network Activity
Signs that something may be wrong on your network:
⚠ Warning
– Unusual outbound traffic at odd hours (malware exfiltrating data)
– New devices appearing on the network you don’t recognise
– DNS requests to unfamiliar domains — malware often uses unusual domains for command and control
– Slow or degraded performance across the network — may indicate active encryption or data exfiltration
– Disabled security tools — malware often attempts to kill antivirus before spreading
If you notice any of these, report to IT immediately.
VPNs and Remote Access
When connecting remotely to your organisation’s internal network, a VPN creates an encrypted tunnel. All traffic flows through the organisation’s security controls as if you were in the office.
- Always use the organisation-provided VPN for accessing internal systems remotely
- Never use a personal or free VPN service on work devices
- Disconnect the VPN when not in active use on shared home networks
Wireless Network Security
| Protocol | Security Level | Recommendation |
|---|---|---|
| Open / No password | None | Never use for work |
| WEP | Broken — cracked in minutes | Never use |
| WPA2-Personal | Adequate for home use | Use strong passphrase (16+ chars) |
| WPA3 | Best available | Preferred where supported |
| WPA2/3-Enterprise | Best for corporate | Uses individual credentials, not shared key |
When was your network last health-checked?
A flat, unsegmented network means one compromised laptop can reach everything you own. Mobile Techs IT Service designs and hardens networks for Gold Coast businesses — business-grade firewalls, VLAN segmentation, secure Wi-Fi, VPN remote access, and monitoring that flags suspicious traffic before it becomes a breach. Home users welcome too — on-site or remote, anywhere in Australia.
Book a network security review → or call 1300 644 588
