Network Segmentation: Limiting Damage in a Cyber Security Network
A cyber security network is a network built so that a problem in one place does not spread everywhere. The most practical way to do that is network segmentation: splitting the network into zones with rules between them. This guide explains how.
Key takeaways
- A flat network lets one infected device reach many others.
- Segmentation splits devices into zones such as office, cameras and plant systems.
- Rules between zones should allow only the traffic each zone needs.
- Test the split regularly; a rule nobody checks may not work.
Why one flat network is risky
On a flat network every device can talk to every other device. If one laptop is infected, the problem can reach servers, cameras and controllers. Segmentation limits that reach, much as fire doors limit a fire in a building.
Common ways to split a network
Most sites start with a few clear zones, then refine them. A typical split looks like this.
| Zone | Typical devices | Basic rule |
|---|---|---|
| Office | Laptops, printers, email | Internet access, limited reach into other zones |
| Servers | ERP, databases, file shares | Reached only by named systems and users |
| Cameras | IP cameras, recorders | Talk only to recorders and viewing stations |
| Plant and gate | Controllers, readers, weighbridge PCs | No direct internet access |
| Guests | Visitor phones and laptops | Internet only |
Rules between zones
Start by blocking everything between zones, then open only what is needed: this system to that server on this port. Log what is blocked, because it shows what you missed and what an attacker tried. Read firewalls, IDS, SIEM and encryption to see how these tools work together.
Checking that segmentation works
A written rule is not proof. Ask a technician to try reaching a plant controller from an office laptop and from the guest network. Review the firewall rules twice a year and remove rules that are no longer used. After any incident, see detecting, containing and recovering to decide which zone rules to tighten.
Planning network segmentation with Suraj Informatics
Suraj Informatics designs cyber security network and monitoring services that include zoning, firewall rules and alerts. We can map your current network and propose zones that suit your site.
Network segmentation: short answers
What is network segmentation?
Dividing a network into separate zones so that traffic between them is controlled.
Is segmentation the same as a VLAN?
A VLAN is one way to create a zone. The rules between zones come from firewalls or access lists.
Will segmentation slow the network?
Not noticeably when it is designed properly, since only the zone boundaries add rules.
Do small sites need it?
Yes. Even separating guests and cameras from the main office network helps.
Talk to our network security team
Share a simple diagram of your network, and we will suggest zones and rules.
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