Firewalls are a critical component in securing the boundary between IT (Information Technology) and OT (Operational Technology) networks. While a single firewall can provide a basic level of security, deploying multiple firewalls—especially from different vendors—can significantly enhance your network’s resilience against cyber threats. This article explores the benefits of using multiple firewalls and provides practical commands and configurations to help you secure your IT/OT environment.
Key Benefits of Multiple Firewalls:
- Resilience: Redundancy ensures that if one firewall fails, the other can continue to protect the network.
- Attack Mitigation: Multiple firewalls can slow down attackers, making it harder for them to bypass security measures.
- Malware Containment: Firewalls can prevent malware from spreading between IT and OT networks.
- Environmental Safety: Protecting OT networks helps prevent potential environmental disasters caused by cyberattacks.
- Operational Continuity: Ensures that critical industrial processes remain operational.
Practical Firewall Configuration Commands:
Here are some commands and configurations to help you set up and manage firewalls effectively:
1. Basic Firewall Rules (Linux – `iptables`):
<h1>Allow necessary traffic between IT and OT networks</h1> iptables -A FORWARD -i eth0 -o eth1 -p tcp --dport 80 -j ACCEPT iptables -A FORWARD -i eth1 -o eth0 -p tcp --sport 80 -j ACCEPT <h1>Block all other traffic</h1> iptables -A FORWARD -j DROP <h1>Save the rules</h1> iptables-save > /etc/iptables/rules.v4
2. Configuring a DMZ (Demilitarized Zone):
<h1>Allow traffic from IT to DMZ</h1> iptables -A FORWARD -i eth0 -o eth2 -p tcp --dport 22 -j ACCEPT <h1>Allow traffic from DMZ to OT</h1> iptables -A FORWARD -i eth2 -o eth1 -p tcp --dport 443 -j ACCEPT <h1>Block direct traffic between IT and OT</h1> iptables -A FORWARD -i eth0 -o eth1 -j DROP
3. Monitoring Firewall Logs:
<h1>View firewall logs in real-time</h1> tail -f /var/log/syslog | grep iptables <h1>Check dropped packets</h1> iptables -L -v -n | grep DROP
4. High Availability with Multiple Firewalls:
For high availability, consider using tools like `keepalived` to manage failover between firewalls:
<h1>Install keepalived</h1>
sudo apt-get install keepalived
<h1>Configure keepalived (edit /etc/keepalived/keepalived.conf)</h1>
vrrp_instance VI_1 {
state MASTER
interface eth0
virtual_router_id 51
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass securepassword
}
virtual_ipaddress {
192.168.1.100
}
}
What Undercode Say:
Implementing multiple firewalls between IT and OT networks is a proven strategy to enhance cybersecurity. While a single firewall provides a basic level of protection, adding a second firewall—preferably from a different vendor—can significantly reduce the risk of a single point of failure. This approach not only mitigates the risk of attackers bypassing your defenses but also ensures operational continuity and environmental safety.
To further strengthen your network, consider implementing a DMZ to securely transfer data between IT and OT networks. Regularly review and update firewall rules to adapt to changing network requirements. Tools like `iptables` and `keepalived` can help you manage and monitor your firewalls effectively.
For advanced protection, explore the use of data diodes or unidirectional gateways to enforce one-way traffic from OT to IT. These tools can provide an additional layer of security, especially for critical infrastructure.
Finally, always ensure that your firewall management interfaces are not exposed to the internet or internal networks. Regularly audit your firewall configurations and logs to detect and respond to potential threats promptly.
For more insights on multi-vendor firewalls, refer to this article: Exploring the Use of Multi-Vendor Firewalls in OT Network Security.
By following these best practices and leveraging the right tools, you can build a robust defense mechanism to protect your IT and OT networks from evolving cyber threats.
References:
Hackers Feeds, Undercode AI
