A scrubbing center is a centralized data cleansing facility used to analyze and remove malicious traffic from a network connection. Also called a traffic scrubbing center, it identifies threats like DDoS attacks and vulnerabilities to ensure that only "clean" traffic reaches the target system. Using these facilities helps organizations prevent downtime and protect sensitive IT infrastructure.
What is a Scrubbing Center?
A scrubbing center functions as a station that specializes in monitoring and filtering network traffic. Organizations such as Internet Service Providers (ISPs), cloud providers, and large enterprises use these centers to off-ramp traffic to an out-of-path location for inspection. When a network is under threat, traffic is redirected to the center, cleaned by an attack mitigation system, and passed back to the network for delivery.
Why Scrubbing Centers matter
Implementing a scrubbing center provides several operational and security benefits: * Service Availability: By filtering out malicious requests, these centers prevent servers from becoming overloaded and going offline. * Infrastructure Protection: They absorb DDoS attacks that have scaled to exceed 1Tbps, protecting internal network hardware from being overwhelmed. * Anomaly Detection: Centers identify unusual patterns that indicate zero-day threats or newly discovered exploits. * Risk Reduction: They act as a barrier for financial services, healthcare providers, and e-commerce sites to prevent data leaks and fraud. * Resource Efficiency: Offloading traffic analysis to a dedicated facility reduces the processing load on your primary application servers.
How a Scrubbing Center works
The scrubbing process typically follows these four stages:
- Traffic Monitoring: The center continuously monitors inbound and outbound data, including web requests, email, and application data, to detect suspicious activity.
- Redirection: When an attack is detected, traffic is redirected to the scrubbing center using BGP (Border Gateway Protocol) or DNS (Domain Name System) changes.
- Filtration and Cleaning: The system separates malicious packets from legitimate requests. It drops or repairs dangerous data while maintaining the integrity of healthy traffic.
- Forwarding: Clean traffic is sent back to the original destination via GRE (Generic Routing Encapsulation) or IPsec tunnels, allowing services to continue without interruption.
Threat detection capabilities
Scrubbing centers are equipped to detect and defend against a wide variety of cyberattacks, including: * Distributed Denial of Service (DDoS): Both volumetric floods at the network layer and low and slow attacks at the application layer. * Botnet Activity: Identifying and quarantining traffic from networks of infected, remotely controlled computers. * Malware Propagation: Blocking the downloads of viruses, Trojans, and other malicious software. * Vulnerability Scans: Detecting and blocking attempts to scan open ports or services for security holes. * Zero-day Exploits: Monitoring for anomalies that indicate unknown attacks. * Protocol Compliance: Performing RFC compliance checks to ensure traffic follows standard internet protocols.
Deployment models: Always-on vs. On-demand
Organizations choose between two primary methods of using a scrubbing center based on their budget and latency requirements.
| Feature | Always-on Scrubbing | On-demand (Automated) Scrubbing |
|---|---|---|
| Traffic Path | All traffic permanently routes through the center. | Traffic only routes through the center during an attack. |
| Latency | Higher baseline latency due to constant detouring. | No added latency during normal operations. |
| Cost | Usually higher, often billed on total traffic volume. | Lower, as services are only used during active mitigation. |
| Response Time | Instant, as traffic is already being filtered. | FastNetMon identifies abnormal patterns and detects attacks within seconds to trigger diversion. |
Best practices
- Automate Diversion Triggers: Use real-time flow analysis (such as NetFlow or IPFIX) to automatically signal scrubbing services when thresholds are met.
- Use Surgical Mitigation: Target only the specific IP addresses or prefixes under attack to avoid filtering unaffected services.
- Maintain Logging and Reporting: Regularly review security posture reports to track incident patterns and refine filtering rules.
- Verify Tunnel Configuration: Ensure GRE or IPsec tunnels are pre-configured so that the transition to the scrubbing center is immediate during an emergency.
- Monitor for False Positives: Periodically check if aggressive filtering rules are inadvertently blocking legitimate users.
Common mistakes
- Mistake: Using "always-on" models for latency-sensitive applications. Fix: Move to an on-demand model where traffic only detours during a verified attack.
- Mistake: Relying on a scrubbing center with insufficient bandwidth. Fix: Ensure the provider has a capacity significantly larger than your transit links, as Cloudflare's system has approximately 15 Tbps of network capacity to handle massive floods.
- Mistake: Manual traffic diversion. Fix: Implement BGP route announcements or FlowSpec rules to automate the steering of traffic the moment an attack is detected.
- Mistake: Ignoring the "Knowledge Gap." Fix: Ensure your provider or internal team has expertise in all layers of the stack (DNS, HTTP, TLS) to distinguish sophisticated malicious traffic from legitimate users.
Scrubbing Centers vs. Anycast Mitigation
While traditional scrubbing centers use dedicated facilities, modern alternatives use anycast networks.
| Aspect | Traditional Scrubbing Center | Anycast Mitigation (Cloudflare model) |
|---|---|---|
| Hardware | Exotic, expensive dedicated hardware. | Commodity servers running specialized software. |
| Traffic Handling | Traffic is sent to a central "citadel" for cleaning. | Every server in the global network participates in mitigation. |
| Response Speed | May require a "switch over" period if not always-on. | Always-on, as Cloudflare mitigates a new DDoS attack every three minutes. |
| Scalability | Limited by the capacity of the specific center. | Scales automatically as the entire network grows. |
FAQ
What is the primary purpose of a scrubbing center?
The main goal is to protect a network from being overwhelmed by malicious traffic, particularly DDoS attacks. It acts as a filter that separates harmful data from legitimate requests, ensuring that services remain available and secure even during an active cyberattack.
How does traffic get to the scrubbing center?
When an attack is identified, the network's traffic is redirected. This is typically achieved by using BGP (Border Gateway Protocol) to update routing paths or by changing DNS records. In automated setups, this happens within seconds of threat detection.
Will using a scrubbing center slow down my website?
If you use an "always-on" model, you may see a slight increase in latency because all traffic must travel through the center's infrastructure before reaching your servers. However, "on-demand" models avoid this by only rerouting traffic when a threat is present.
What is the difference between clean and dirty traffic?
"Dirty" traffic refers to the mix of legitimate user requests and malicious data (like botnet queries or volumetric floods) entering a network. "Clean" traffic is what remains after the scrubbing center has filtered out the harmful components.
Who should use a scrubbing center?
Any organization providing online services or operating networked IT infrastructure can benefit. This includes e-commerce sites, financial institutions, healthcare providers, cloud services, and government agencies that cannot afford downtime or data breaches.
