What is the most common form of DDoS?

Common Types of DDoS Attacks

SYN Flood:

Characteristics: Exploits TCP three-way handshake to exhaust server connection resources.

Defense: SYN cookies, limiting SYN queue size, firewall.

UDP Flood:

Characteristics: Sends numerous UDP packets, consuming server processing resources.

Defense: Limiting UDP packet quantity, firewall, intrusion detection systems (IDS).

HTTP Flood:

Characteristics: Sends large volumes of legitimate HTTP requests, depleting server resources.

Defense: Rate limiting, Web Application Firewall (WAF), Content Delivery Network (CDN).

Less Common DDoS Attack Types

DNS Amplification Attack:

Characteristics: Uses DNS servers to amplify small requests into large responses, consuming bandwidth.

Defense: Limiting DNS requests, firewall, Intrusion Detection and Prevention Systems (IDPS).

NTP Amplification Attack:

Characteristics: Uses NTP servers to amplify small requests into large responses, consuming bandwidth.

Defense: Disabling NTP MONLIST, limiting NTP access, firewall.

SSDP Amplification Attack:

Characteristics: Uses SSDP protocol to amplify small requests into large responses, consuming bandwidth.

Defense: Disabling unnecessary SSDP services, firewall, IDPS.

ICMP Flood:

Characteristics: Sends large volumes of ICMP requests, exhausting server resources.

Defense: Limiting ICMP request quantity, firewall, IDPS.

Slowloris Attack:

Characteristics: Sends incomplete HTTP requests, exhausting server connection resources.

Defense: Setting connection timeouts, using load balancers, WAF.

Protection Measures

1. Traffic Filtering

Definition: Traffic filtering is a technique that analyzes and screens incoming network or server traffic to identify and block malicious traffic. It ensures that only legitimate and secure traffic can pass through, protecting networks and servers from attacks.

Key Points:

• Firewall and IDS/IPS: Configure rules to filter abnormal traffic.
• Web Application Firewall (WAF): Protect web applications by filtering HTTP/HTTPS traffic.
• Content Delivery Network (CDN): Preliminary filtering of traffic before reaching servers.

2. Rate Limiting

Definition: Rate limiting is a technique that prevents network or server overload by restricting the number of requests processed within a specific timeframe. It controls traffic rates to prevent denial-of-service attacks initiated by malicious users and ensures system stability.

Key Points:

• Traffic shaping: Control the sending rate of traffic.
• Rate limiter: Set maximum requests allowed per second.
• Application-level rate limiting: Apply limits to specific applications or APIs.

3. Black Hole Routing

Definition: Black hole routing isolates and eliminates attack traffic by redirecting it to an invalid address (black hole). This method effectively mitigates the impact of malicious traffic on networks and servers, protecting normal business operations.

Key Points:

• Manual configuration: Network administrators manually set up black hole routing.
• Automated configuration: Systems automatically detect attacks and set up black hole routes.
• Cooperative defense: Collaborate with ISPs or cloud service providers to implement black hole routing.

4. Other Protection Measures

• Load Balancing: Distribute traffic across multiple servers to reduce the load on individual servers.
• Elastic Scaling: Automatically adjust resources to cope with traffic fluctuations and ensure service availability.
• Anycast: Distribute traffic to servers in multiple geographic locations to mitigate attack pressure.
• Threat Intelligence: Use security data to identify potential threats and update protection strategies.

This content provides a comprehensive overview of common DDoS attack types, their characteristics, and effective defense strategies, presented in clear and grammatically correct English.