What is the principle of DDOS attack? Analysis of core knowledge of cyber security

the deep integration of digital office and the Internet, network attacks have become a common risk that threatens the security of enterprise and personal information. Among them, DDOS attacks have always been the key prevention objects in the field of cyber security due to their strong destructive power and relatively low implementation threshold. Many people only know that such attacks will lead to website paralysis and service interruption, but they have little understanding of the operation logic behind them. This article will disassemble the principle of DDOS attacks from multiple dimensions, combine the actual operation mechanism, classification differences and other content, and build a complete cyber security cognitive framework for readers to help improve risk prevention awareness.

What is the basic logic of DDOS attack principle?

to understand the principle of DDOS attack, we must first start from its core objectives and operating premise, which is the basis for mastering all derivative mechanisms.

1. Core objective: depletion of target resources

The core logic of the

DDOS attack principle revolves around "resource exhaustion", where the resources include the server's bandwidth, CPU computing power, memory space, etc. Under normal circumstances, the server will process various access requirements in an orderly manner according to the priority of user requests and its own load; while DDOS attacks will launch requests that far exceed the server's load limit in a short time, leaving the server in a state of "overwhelmed", and eventually unable to respond to the normal requests of legitimate users to achieve the purpose of the attack.

2, the key role of distributed initiation

The "distributed" in the

DDOS attack principle is the core feature that distinguishes it from ordinary DOS attacks. Ordinary DOS attacks only rely on a single attack source to initiate a request, which is easy to be identified and intercepted by the protection system; while DDOS attacks will control a large number of infected devices, which is often called "broilers". Attacks launched simultaneously from different network nodes around the world can not only instantly amplify the attack traffic, but also hide the real attack source, greatly improving the success rate and concealment of the attack.

2. What are the common classifications of DDOS attack principles?

depending on the type of server resources targeted by the attack, the principle of DDOS attack will also present different ways of operation, and the corresponding attack effect and protection difficulty are also different.

1, bandwidth consumption DDOS attack principle

the principle of this type of DDOS attack focuses on the server's internet bandwidth resources, by sending a large number of meaningless data packets, filling the target server's exit bandwidth. For example, the common UDP flood attack, the attacker will send a large number of UDP data packets to the random port of the target server, the server will try to reply after receiving the "port unreachable" message, further consuming its own bandwidth resources, eventually resulting in legitimate users' requests cannot reach the server through limited bandwidth.

2, resource exhaustion DDOS attack principle

this kind of DDOS attack principle targets the server's CPU, memory and other computing resources. Take the SYN flood attack as an example, the attacker will send a large number of SYN requests to the server that forge the source Internet Protocol Address. After receiving the request, the server will allocate resources to establish a half connection and wait for the reply of the source IP. However, because the source address is forged, the server will maintain these half connections, and eventually exhaust all available connection resources and cannot process new legitimate requests.

3. What is the amplification mechanism in the principle of DDOS attack?

in order to further improve the efficiency of attacks, attackers will use the characteristics of network protocols to design amplification mechanisms, which is also a very confusing and destructive part of the principle of DDOS attacks.

1, the use of public servers to achieve traffic amplification

the core of this kind of DDOS attack principle is to use public servers on the Internet, such as DNS servers, NTP servers, etc., to convert small traffic attack requests into large traffic attack responses. Attackers will send requests to these public servers that forge the source IP as the target server. After receiving the request, the server will send a large amount of response data to the forged source IP. Eventually, all response traffic will flow to the target server, forming an attack traffic that far exceeds the attacker's own output ability.

2, the influence factor of magnification

The magnification in

DDOS attack principle mainly depends on the protocol type and server configuration. For example, the magnification of the NTP protocol can reach hundreds of times, and an attacker sending a request of tens of bytes can trigger the server to return tens of KB or even hundreds of KB of response data; while the amplification of the DNS protocol is usually between 10-100 times, and the specific value will fluctuate according to the query content of the request and the cache status of the server.

IV. What is the relationship between the principle of DDOS attack and the means of defense?

understand the principle of DDOS attack is not only to recognize the attack, but also to provide a basis for defense.

1, defense logic for bandwidth consumption

based on the principle of bandwidth-consuming DDOS attacks, the core of defense is to achieve traffic cleaning and bandwidth expansion. Enterprises can deploy professional traffic cleaning equipment to identify and filter out meaningless attack data packets, and only allow legitimate traffic to enter the server; at the same time, with the help of Cloud as a Service provider's elastic bandwidth service, temporarily increase the bandwidth limit in the event of an attack to avoid the attack traffic directly filling the exit bandwidth.

2, defense logic against resource exhaustion

combined with the principle of resource-exhausted DDOS attacks, the focus of defense is to optimize server connection management and request verification. For example, by configuring SYN cookies, the server does not directly allocate connection resources when receiving SYN requests, but returns a cookie with authentication information. Only when the client side returns the correct cookie, the connection is officially established, so as to avoid being used up by forged requests.

sum up, this paper disassembles the DDOS attack principle from the four dimensions of basic logic, classification difference, amplification mechanism and defense association. The core focuses on "distributed exhaustion of target resources". Different types of attacks will design operation mechanisms for different resources of the server, and amplification mechanism further enhances the destructive power of the attack. Understanding these DDOS attack principles can not only help us identify network risks, but also provide professional basis for formulating effective defense strategies, which is an important foundation for building a cyber security protection system.