Construction of Industrial Network DDoS Defense System: Collaborative Strategy Between Firewalls and IoT Routers
In the current era of deep integration between Industry 4.0 and the Internet of Things (IoT), industrial networks are facing unprecedented security challenges. Distributed Denial of Service (DDoS) attacks, characterized by their "low cost and high destructiveness," have emerged as the "number one killer" threatening critical infrastructure such as energy, transportation, and manufacturing. One energy enterprise experienced a 72-hour shutdown of three chemical plants due to a SYN flood attack, resulting in direct economic losses exceeding $230 million. Another automobile manufacturer suffered data leaks from its production line due to an HTTP flood attack, severely damaging its brand reputation. Faced with increasingly sophisticated attack methods, industrial networks urgently need to construct a "defense-in-depth system" centered around firewalls and IoT routers.
DDoS attacks on Industrial Control Systems (ICS) are exhibiting a trend towards "high-value" targets. Attackers are no longer satisfied with causing service disruptions but are instead launching compound attacks by precisely targeting control layer devices (such as Programmable Logic Controllers (PLCs) and Remote Terminal Units (RTUs)) to achieve a combination of "shutdown-ransom-data theft." In 2024, 32% of global ICS attack incidents directly targeted IoT routers, leveraging their role as network hubs to launch traffic amplification attacks.
Modern DDoS attacks have evolved into a hybrid attack model combining "traffic-based, protocol-based, and application-layer" attacks:
Traffic-based attacks: These attacks occupy bandwidth through methods such as UDP floods and ICMP floods. A rail transit signaling control system once suffered a UDP reflection attack with a peak of 800 Gbps.
Protocol-based attacks: These attacks exploit vulnerabilities in the TCP protocol (such as SYN floods and Land attacks) to exhaust server connection resources. A power monitoring system experienced 100,000 devices going offline due to a SYN flood attack.
Application-layer attacks: These attacks simulate normal business requests (such as HTTP slow attacks). A pharmaceutical cold chain monitoring platform experienced delays in temperature data reporting due to a CC attack, resulting in the scrapping of vaccines worth $5 million.
Attackers control millions of IoT devices worldwide through botnets to launch attacks. An energy pipeline monitoring system once suffered a distributed attack from 3.2 million IP addresses across 152 countries, rendering traditional IP blacklist-based defense methods completely ineffective.
As network entry points, IoT routers need to possess the following core defense capabilities:
Traffic Cleaning: Identify malicious traffic through Deep Packet Inspection (DPI) technology. For example, the USR-G809s IoT router employs a hardware acceleration engine to achieve an AES-256 encryption throughput of 2.8 Gbps while supporting SYN Cookies technology to defend against SYN flood attacks. When abnormal SYN requests are detected, the server does not allocate resources immediately but only returns a SYN+ACK packet with a sequence number. Connection resources are allocated only after the client completes the three-way handshake.
Connection Number Limitation: To counter CC attacks, IoT routers can limit the maximum number of concurrent connections from a single IP. An automobile manufacturing enterprise successfully blocked a CC attack on its production management system by configuring the connection number threshold of the USR-G809s to control HTTP request connections at 500 per second.
Protocol Filtering: Only necessary industrial protocols (such as Modbus TCP and Profinet) are allowed, while unauthorized protocol traffic is intercepted. An energy enterprise reduced its attack surface by 70% by configuring ACL rules on its IoT router to prohibit external network access to its internal OPC UA server.
Firewalls need to form a closed-loop defense of "detection-blocking-tracing" with IoT routers:
Behavior Analysis: Identify abnormal traffic patterns based on machine learning algorithms. A next-generation firewall (NGFW) deployed in a rail transit signaling control system can establish a baseline model by analyzing historical traffic data, detect traffic fluctuations exceeding the baseline by more than 20% in real-time, and automatically trigger alarms.
Rate Limiting: To counter UDP flood attacks, firewalls can set a threshold for the maximum number of packets per second (PPS). A power monitoring platform successfully resisted an ICMP flood attack with a peak of 500,000 pps by limiting ICMP message rates to 100 pps.
Threat Intelligence Collaboration: Share attack signature libraries with cloud protection platforms. A pharmaceutical cold chain enterprise shortened the identification time for new HTTP slow attacks from 30 minutes to 10 seconds by integrating threat intelligence from Alibaba Cloud WAF to update firewall rules in real-time.
In the China-Russia Eastern Gas Pipeline Project, the USR-G809s IoT router and firewall constructed a three-dimensional defense system featuring "triple network redundancy + AES-256 encryption + DDoS protection":
Network Redundancy: Support intelligent switching among 5G/4G/satellite triple links, with a switching time of less than 50 ms in case of a single link failure, avoiding exposure of attack surfaces due to network interruptions.
Encrypted Transmission: All SCADA system instructions and sensor data are encrypted using the AES-256-GCM mode, ensuring that intercepted data packets cannot be decrypted.
Attack Defense: Deploy an AI-based abnormal traffic detection system capable of identifying 12 types of threats, including DDoS attacks and man-in-the-middle attacks. In 2024, it successfully blocked an APT attack on a compressor control system, identifying and intercepting malicious instructions encrypted with RSA-2048 during the AES-256 decryption process.
In an automobile assembly plant, the USR-G809s IoT router achieved transparent encrypted transmission of six types of industrial protocols, including Modbus TCP, Profinet, and OPC UA:
Protocol Conversion: Encapsulate plaintext protocols into AES-256 encrypted DTLS tunnels through a built-in protocol parsing engine, without modifying existing PLC programs.
Zero-Trust Access: Implement fine-grained access control based on device digital certificates, allowing only authorized IP addresses to access critical devices through specific ports.
Audit Trailing: Record encrypted metadata of all protocol interactions to support PCI DSS compliance audits. After deployment, unauthorized device access events decreased by 97%, and protocol parsing error rates dropped from 1.2% to 0.03%.
In the global distribution of COVID-19 vaccines, the USR-G809s IoT router constructed a system featuring "end-to-end AES-256 encryption + blockchain evidence storage":
Temperature Data Encryption: Cold storage sensor data is encrypted using AES-256-GCM before being uploaded to the cloud, ensuring that intercepted data packets cannot be decrypted.
Blockchain Evidence Storage: Encrypted temperature records and GPS trajectories are stored on the blockchain to ensure data immutability. When a batch of vaccines was rejected due to transportation overheating, blockchain evidence storage data successfully helped the pharmaceutical enterprise prove transportation compliance.
Multi-level Alarms: In case of temperature abnormalities, the system notifies responsible personnel through AES-256 encrypted SMS/APP push notifications to prevent interception and tampering of alarm information.
The National Institute of Standards and Technology (NIST) has initiated the standardization process for post-quantum cryptography (PQC), with the expectation of releasing standards for anti-quantum algorithms such as CRYSTALS-Kyber by 2029. IoT routers need to proactively deploy hybrid encryption solutions, combining Kyber key encapsulation mechanisms with AES-256 to construct a "quantum-secure transition period" protection system.
Analyze network traffic characteristics through machine learning to achieve dynamic adjustment of encryption algorithms: Use AES-128 during low-risk periods to improve performance and automatically switch to AES-256 during high-risk periods. Laboratory tests have shown that this technology can increase IoT router throughput by 40% while maintaining the same level of security.
Integrate edge computing modules into IoT routers to achieve "encryption upon data collection." The next-generation product of the USR-G809s already supports AES-256 encryption of sensor data upon access, eliminating the risk of plaintext exposure in IoT router memory.
In the wave of industrial digital transformation, DDoS attacks have become the "Sword of Damocles" hanging over critical infrastructure. By constructing a collaborative defense system of "IoT routers + firewalls" and combining technological means such as AES-256 encryption, behavior analysis, and threat intelligence collaboration, it is possible to effectively resist hybrid attacks including traffic-based, protocol-based, and application-layer attacks. In the future, with breakthroughs in technologies such as post-quantum encryption and AI security, the security protection system of industrial networks will evolve from "passive defense" to "active immunity," constructing a more robust digital defense line for Industry 4.0.
