There are many methods and techniques for DDoS (Distributed Denial of Service) attacks, and attackers can choose different methods based on their goals and the complexity of their attack techniques. The following are some common DDoS attack methods:

　　UDP Flood attack: The attacker sends a large number of forged UDP packets to the target server to consume its bandwidth and processing power.

　　TCP SYN Flood attack: The attacker sends a large number of false TCP connection requests (SYN), causing the server to continuously try to establish connections, thereby occupying server resources.

　　ICMP Flood attack: The attacker sends a large number of ICMP echo requests (ping requests), occupying server resources.

　　HTTP GET/POST attack: The attacker sends a large number of HTTP GET or POST requests to the target server, occupying its bandwidth and processing power.

　　Slowloris attack: The attacker uses a small number of connections to keep the HTTP connection open, occupying server resources and making it unable to serve other requests.

　　NTP and DNS amplification attacks: The attacker disguises himself as the victim's IP address and sends requests to NTP or DNS servers. These servers will respond with large amounts of data and bounce the attack traffic back to the victim.

　　SSDP attack: Attackers abuse the vulnerabilities of UPnP devices and send a large number of SSDP requests to occupy the target bandwidth.

　　ACK/PSH Flood attack: The attacker sends a large number of TCP ACK or PSH packets, occupying server resources.

　　HTTP compression attack: The attacker sends a request containing a large amount of compressible data, occupying the server's CPU resources to decompress the data.

　　Memcached amplification attack: The attacker disguises himself as the victim's IP address and sends requests to Memcached servers. These servers will respond with large amounts of data and bounce the attack traffic back to the victim.

　　WebSocket attack: Attackers use WebSocket connections to send a large number of data packets, occupying server resources.

　　SSL/TLS handshake attack: The attacker establishes multiple SSL/TLS connections and consumes server resources during the handshake process.

　　Pipe Attack: Attackers use a large number of different types of attack techniques to confuse and evade defenses, making protection more complex.

　　Application Layer Attacks: These attacks are typically application-specific, such as attacks on databases, game servers, or web applications.

　　Volumetric attack: This attack type involves large amounts of traffic designed to overwhelm the victim's network infrastructure.

　　Protocol attack: Attackers may target weaknesses in specific protocols, such as DNS or NTP.

　　Please note that attackers may combine multiple attack methods and use distributed networks to increase attack intensity and make it difficult to trace the source of the attack. Therefore, network administrators need to adopt multi-layered defense strategies to deal with various DDoS attacks.