Network segmentation (IT/OT separation) in SCADA systems - Mini Project: Build & Apply

Network segmentation (IT/OT separation)

📖 Scenario: You are working in a factory that uses SCADA systems to control machines. The factory wants to keep its IT network (office computers, email) separate from its OT network (machines, sensors) to improve security. You will create a simple representation of this network segmentation using Python dictionaries.

🎯 Goal: Build a Python dictionary that represents two separate networks: IT and OT. Then add a configuration variable to define which network is active. Finally, write code to list all devices in the active network.

📋 What You'll Learn

Create a dictionary called networks with two keys: 'IT' and 'OT'

Each key should map to a list of device names as strings

Create a variable called active_network and set it to either 'IT' or 'OT'

Write a for loop to iterate over the devices in the active network

Print each device name on its own line

💡 Why This Matters

🌍 Real World

Factories and industrial plants separate IT and OT networks to protect machines from cyber attacks and keep operations safe.

💼 Career

Understanding network segmentation is important for roles in industrial cybersecurity, network administration, and SCADA system management.

1

Create the network dictionary

Create a dictionary called networks with two keys: 'IT' and 'OT'. The 'IT' key should map to a list containing 'Office_PC1' and 'Email_Server'. The 'OT' key should map to a list containing 'PLC1' and 'SensorA'.

SCADA systems

# Your code here

Hint

Use curly braces {} to create a dictionary. Use square brackets [] for lists.

2

Set the active network

Create a variable called active_network and set it to the string 'OT'.

SCADA systems

networks = {
    'IT': ['Office_PC1', 'Email_Server'],
    'OT': ['PLC1', 'SensorA']
}
# Your code here

Hint

Assign the string 'OT' to the variable active_network.

3

Loop over devices in the active network

Write a for loop using the variable device to iterate over the list of devices in networks[active_network].

SCADA systems

networks = {
    'IT': ['Office_PC1', 'Email_Server'],
    'OT': ['PLC1', 'SensorA']
}
active_network = 'OT'
# Your code here

Hint

Use for device in networks[active_network]: to loop over devices.

4

Print each device name

Inside the for loop, write a print(device) statement to display each device name.

SCADA systems

networks = {
    'IT': ['Office_PC1', 'Email_Server'],
    'OT': ['PLC1', 'SensorA']
}
active_network = 'OT'
for device in networks[active_network]:
    # Your code here

Hint

Use print(device) inside the loop to show each device.

Practice

1. What is the main purpose of network segmentation between IT and OT systems in SCADA environments?

easy

A. To improve security by separating critical industrial systems from general IT networks

B. To increase the speed of data transfer between devices

C. To reduce the number of devices needed in the network

D. To allow all devices to communicate freely without restrictions

Solution

1. Step 1: Understand the role of network segmentation

   Network segmentation divides a network into parts to isolate sensitive systems from less secure ones.

2. Step 2: Apply this to IT and OT systems

   Separating IT (office systems) from OT (industrial control) protects critical SCADA systems from cyber threats.

3. Final Answer:

   To improve security by separating critical industrial systems from general IT networks -> Option A

4. Quick Check:

   Network segmentation = Security improvement [OK]

Hint: Segmentation means separation for security, not speed or device count [OK]

Common Mistakes:

• Thinking segmentation speeds up network
• Believing segmentation reduces devices
• Assuming segmentation allows free communication

2. Which of the following VLAN configurations correctly separates IT and OT traffic?

easy

A. VLAN 20 for IT devices, VLAN 10 for OT devices, but no traffic control

B. VLAN 10 for both IT and OT devices without any ACLs

C. VLAN 10 for IT devices, VLAN 20 for OT devices, with ACLs controlling traffic between them

D. No VLANs, all devices on the same network segment

Solution

1. Step 1: Identify VLAN usage for separation

   Using separate VLANs for IT and OT devices isolates their traffic logically.

2. Step 2: Check for access control lists (ACLs)

   ACLs control and restrict traffic between VLANs, enhancing security.

3. Final Answer:

   VLAN 10 for IT devices, VLAN 20 for OT devices, with ACLs controlling traffic between them -> Option C

4. Quick Check:

   Separate VLANs + ACLs = Proper segmentation [OK]

Hint: Separate VLANs plus ACLs control traffic properly [OK]

Common Mistakes:

• Using same VLAN for IT and OT
• Not applying ACLs between VLANs
• Ignoring VLANs and traffic control

3. Given this simplified network ACL rule:
permit ip 192.168.1.0 0.0.0.255 10.0.0.0 0.0.0.255
What does this rule allow?

medium

A. Allow all IP traffic from 192.168.1.x to 10.0.0.x

B. Block all traffic from 192.168.1.x to 10.0.0.x

C. Allow traffic only from 10.0.0.x to 192.168.1.x

D. Allow traffic from any IP to any IP

Solution

1. Step 1: Understand ACL syntax

   The rule permits IP traffic from source 192.168.1.0/24 to destination 10.0.0.0/24.

2. Step 2: Interpret the wildcard masks

   Wildcard 0.0.0.255 means any IP in the last octet, so 192.168.1.x to 10.0.0.x is allowed.

3. Final Answer:

   Allow all IP traffic from 192.168.1.x to 10.0.0.x -> Option A

4. Quick Check:

   permit ip source to destination = Allow traffic [OK]

Hint: permit ip source wildcard destination wildcard means allow that traffic [OK]

Common Mistakes:

• Confusing source and destination
• Misreading wildcard masks
• Assuming rule blocks traffic

4. You configured VLANs for IT and OT but OT devices cannot communicate with the SCADA server. What is the most likely cause?

medium

A. OT devices have incorrect IP addresses outside VLAN range

B. VLAN IDs for IT and OT are the same

C. SCADA server is powered off

D. Missing or incorrect ACL rules blocking OT to SCADA traffic

Solution

1. Step 1: Check VLAN separation

   If VLAN IDs are different, devices are separated logically, so VLAN ID conflict is unlikely.

2. Step 2: Review ACL rules

   ACLs often block traffic between VLANs; missing or wrong ACLs can prevent OT devices from reaching SCADA server.

3. Final Answer:

   Missing or incorrect ACL rules blocking OT to SCADA traffic -> Option D

4. Quick Check:

   ACL misconfiguration = communication failure [OK]

Hint: Check ACLs first when VLANs separate but no communication [OK]

Common Mistakes:

• Assuming VLAN IDs are same without checking
• Ignoring ACL impact on traffic
• Jumping to hardware power issues first

5. You want to allow only specific IT workstations to access OT SCADA devices. Which approach best achieves this while maintaining network segmentation?

hard

A. Place all IT and OT devices in the same VLAN to simplify access

B. Create a dedicated VLAN for those IT workstations and configure ACLs to allow only their IPs to OT VLAN

C. Disable all ACLs between IT and OT VLANs to allow free communication

D. Use a single firewall rule allowing all IT subnet to access OT subnet

Solution

1. Step 1: Understand segmentation with selective access

   Segmentation requires separate VLANs; selective access needs controlled rules.

2. Step 2: Apply VLAN and ACLs for fine control

   Creating a dedicated VLAN for allowed IT workstations and ACLs restricting access by IP ensures security and selective access.

3. Final Answer:

   Create a dedicated VLAN for those IT workstations and configure ACLs to allow only their IPs to OT VLAN -> Option B

4. Quick Check:

   Dedicated VLAN + ACLs = selective secure access [OK]

Hint: Use VLAN plus ACLs to limit access, not open networks [OK]

Common Mistakes:

• Mixing IT and OT in one VLAN
• Disabling ACLs completely
• Using broad firewall rules without IP filtering