MikroTik Network Segmentation: Isolating IoT Devices for Better Security

Why Network Segmentation Became Essential

As my home network expanded with dozens of IoT devices - from smart bulbs to security cameras - the security implications kept me awake at night. These devices are notorious security risks, and I refused to let my thermostat become a backdoor into my main network. MikroTik’s RouterOS offered the perfect toolkit for creating hardened network partitions. This journey into network isolation taught me that proper segmentation isn’t just about security. It’s about maintaining network sanity.

Implementing the MikroTik Isolation Framework

1. Building the Virtual Wireless Perimeter

Creating a dedicated wireless segment was my first line of defense. The MikroTik CLI made this straightforward:

/interface wireless add \
  name=iot_network \
  master-interface=wlan1 \
  ssid="IoT_Segment" \
  mode=ap-bridge \
  security-profile=iot_profile \
  disabled=no

2. Subnet Architecture and DHCP Configuration

I carved out a dedicated subnet with tight DHCP controls:

/ip address add address=10.0.4.1/24 interface=iot_network
/ip pool add name=pool-iot ranges=10.0.4.2-10.0.4.254
/ip dhcp-server add interface=iot_network address-pool=pool-iot disabled=no
/ip dhcp-server network add address=10.0.4.0/24 gateway=10.0.4.1 dns-server=10.0.0.2

3. Crafting the Firewall Rules

The real magic happened in the firewall rules. This critical rule drops all traffic from IoT to my main LAN:

/ip firewall filter add \
  chain=forward \
  src-address=10.0.4.0/24 \
  dst-address=10.0.0.0/22 \
  action=drop \
  comment="Block IoT to Main LAN"

Refining the Security Posture

Strategic Access Exceptions

Complete isolation isn’t practical - I still needed management access. This rule allows my admin workstation limited access:

/ip firewall filter add \
  chain=forward \
  src-address=10.0.3.100/32 \
  dst-address=10.0.4.0/24 \
  protocol=tcp \
  dst-port=22,80,443 \
  action=accept \
  comment="Allow Admin to IoT" \
  place-before=1

Essential Service Permissions

Even isolated devices need DNS. This exception keeps them functional without compromising security:

/ip firewall filter add \
  chain=forward \
  src-address=10.0.4.0/24 \
  dst-address=10.0.0.2 \
  protocol=udp \
  dst-port=53 \
  action=accept \
  comment="Allow IoT DNS"

Verification and Testing

Before declaring victory, I ran these crucial checks on the MikroTik:

/interface wireless registration-table print
/ip firewall connection print
/tool ping 10.0.4.1 src-address=10.0.3.100

Advantages of Interface-Based Segmentation

This approach offers distinct benefits for IoT isolation:

  1. Operational Simplicity: Each network segment exists as a self-contained interface with direct firewall control
  2. Transparent Traffic Flow: Rules reference concrete interfaces rather than abstract tags

For IoT segmentation specifically, this method provides the perfect balance. Strong isolation through firewall policies while maintaining essential internet access. The configuration stays focused and manageable without layered abstraction.

Key Implementation Takeaways

  1. Rule Ordering: MikroTik processes firewall rules top-down. Position matters.
  2. NAT Considerations: Essential masquerade rules ensure IoT devices can reach the internet.

This configuration strikes the perfect balance between security and functionality. My smart devices can’t talk to my servers, but they can still forecast tomorrow’s rain. That’s network segmentation done right.

2025-08-11