DDoS Mitigation

A mitigation architecture that routes all incoming traffic through a high-capacity scrubbing center for deep packet inspection. Malicious requests are identified and dropped based on signature matching, protocol anomalies, and rate thresholds, while legitimate traffic is forwarded to the origin server. This is essential when scraping bots are used as a smokescreen for a volumetric DDoS attack.

• Inline vs. Out-of-Path: Inline scrubbing inspects traffic in real-time without diversion; out-of-path uses BGP routing to redirect traffic during an attack.
• Signature-Based Filtering: Matches packet payloads against known attack patterns.
• Heuristic Analysis: Identifies zero-day attacks by detecting statistical deviations from baseline traffic profiles.

A network addressing and routing methodology where a single IP address is announced from multiple geographically dispersed points of presence (PoPs). During an attack, traffic is routed to the nearest topological node, diluting the volumetric flood across a global server network. This prevents any single data center from being overwhelmed by a botnet-driven scraping or DDoS campaign.

• BGP Announcement: The same /24 IP block is advertised from multiple autonomous systems.
• Proximity Routing: Internet routing tables direct users to the closest available node.
• Resilience: If one PoP is saturated, traffic automatically fails over to the next nearest location.

A defense mechanism that intercepts the TCP three-way handshake to protect origin servers from SYN flood attacks. The proxy acts as an intermediary, completing the handshake with the client on behalf of the server. Only after the client proves it is not a spoofed source by responding with the final ACK does the proxy establish a separate, clean connection to the backend. This thwarts the resource exhaustion common in scraping-intensified attacks.

• SYN Cookie Implementation: Encodes cryptographic state into the SYN-ACK sequence number to avoid allocating memory until the handshake is verified.
• Connection Deferred: Backend server resources are only consumed after client legitimacy is established.
• Stateless Operation: The proxy can handle millions of half-open connections without memory exhaustion.

A countermeasure that creates a null route (often via BGP) to drop all traffic destined for a targeted IP address before it reaches the protected network. While crude, it is an effective last-resort tactic to preserve upstream bandwidth and protect adjacent infrastructure during a massive attack. Traffic is discarded at the network edge, preventing the volumetric flood from saturating internal links.

• RTBH (Remotely Triggered Black Hole): A router is signaled to install a null route for a specific prefix, often triggered by a flow analyzer detecting an anomaly.
• Selective Blackholing: Drops traffic only to the specific /32 IP under attack, preserving other services on the same network segment.
• Collateral Damage: Legitimate traffic to the targeted IP is also dropped, making this a temporary triage measure.

The application of granular traffic filters at the network edge using BGP Flow Specification (RFC 8955). This allows for the dynamic propagation of filter rules—including packet length, protocol, and source/destination prefixes—to upstream providers. Unlike simple rate limiting, Flow Spec can surgically drop packets matching a specific attack signature before they converge on the target, mitigating application-layer DDoS attacks embedded in scraping traffic.

• Match Criteria: Filters on L3/L4 attributes like IP protocol, port, TCP flags, and packet length.
• Action: Traffic matching the rule can be rate-limited, sampled, or dropped entirely.
• Dynamic Propagation: Rules are disseminated via BGP updates, enabling rapid, coordinated defense across transit providers.

A server that sits in front of origin web servers and forwards client requests. In DDoS mitigation, a reverse proxy terminates the client TCP connection, inspects the request, and only forwards valid, non-malicious traffic to the backend. This architecture hides the origin server's IP address, making it impossible to target directly with volumetric floods, and provides a centralized point for implementing Web Application Firewall (WAF) rules and bot challenges.

• IP Obfuscation: The origin server's real IP is never exposed to the public internet.
• SSL/TLS Termination: Offloads cryptographic processing from the origin, absorbing computational attack vectors.
• Caching: Serves cached content for repeated requests, reducing the load on backend infrastructure during an attack.