How to solve CC attacks? Common problems and solutions

in today's rapid development of Internet business, network attacks have emerged in an endless stream. Among them, CC attacks have become a headache for many webmasters and operation and maintenance personnel due to their low cost and high concealment. After many corporate websites encounter CC attacks, access is slow, server resources are exhausted or even down, which seriously affects the normal operation of the business. Faced with this continuous application layer attack, many administrators feel helpless. This article will start from the principle of CC attacks, systematically sort out common attack characteristics, and give practical investigation ideas and solutions to help readers establish a complete protection system. Whether you are a novice in website operation and maintenance or a technician with some experience, you can get practical coping strategies from it.

First, what are the common forms of CC attacks

To solve CC attacks, it is first necessary to accurately identify their attack characteristics. CC attacks mainly send a large number of seemingly legitimate requests to target websites through proxy servers or botnets, which consume server connection resources and database query capabilities, resulting in normal users unable to access.

1, abnormal soaring traffic

When a website suddenly appears hundreds or even thousands of requests per second, and the source IP is scattered and the User-Agent is chaotic, it is likely to be under CC attacks. Under normal circumstances, the website traffic curve is relatively flat, while the attack traffic will show a steep peak.

2, server CPU and memory occupancy are high

attack requests often target dynamic pages or database interfaces, resulting in a large number of server processing processes piled up, CPU usage maintained at more than 90% for a long time, memory occupancy continued to climb, and eventually led to slow system response or crash.

Second, the first step of how to solve the CC attack: quickly locate the source of the attack

After confirming the CC attack, the first task is to quickly locate the attack characteristics and sources, in order to take targeted measures. By analyzing the access log and network connection status, you can narrow the scope of investigation.

1, view the number of server connections

use netstat or ss command to count the current TCP connection status, focusing on the TIME_WAIT and SYN_RECV state of the number of connections. If a large number of connections are from the same IP segment or the same proxy feature, the source of the attack can be basically locked.

2, analyze the web access log

check the URL with the most frequent access in the log, request interval, and request header information. Attackers often focus on requesting a resource-consuming interface, such as search, login, or report pages. These log features can help you quickly identify attack patterns.

Third, the core of how to solve the CC attack: Multi-layer protection strategy

After locating the source of the attack, it is necessary to deploy a multi-layer protection strategy to carry out three-dimensional defense from the network layer, the application layer to the business layer. It is often difficult to fully resist high-intensity CC attacks by relying on a certain layer of protection alone.

1. Enable web application firewall

configure WAF rules, limit the request frequency of a single IP, and set a reasonable access threshold. At the same time, turn on human-machine authentication, and return a verification code page for suspicious requests, which can effectively intercept a large number of automated attack traffic.

2. Optimize server performance and cache

Add Redis or Memcached cache to dynamic pages to reduce database pressure. At the same time, adjust web server parameters, such as maximum number of connections, timeout time, etc., to avoid resources being exhausted by invalid requests. For static resources, CDN can be enabled to accelerate the dispersion of traffic.

3. Implement IP blacklist and rate limit

dynamically ban malicious IPs or IP segments according to attack characteristics. Use nginx's limit_req module or iptables for connection limit to quickly cut off abnormal traffic when an attack occurs.

IV. Long-term protection and monitoring mechanism for CC attacks

Short-term response can only solve the urgent need. Establishing a long-term monitoring and emergency response mechanism can continue to ensure business stability. It is essential to regularly check and update the protection strategy.

1. Deploy a traffic monitoring and alarm system

Use tools such as Zabbix or Prometheus to monitor traffic, connections and resource usage in real time, set a reasonable threshold, and automatically trigger an alarm when the indicator is abnormal, so that the operation and maintenance personnel can intervene in the first time.

2, Develop emergency plans and regularly drill

Prepare a complete CC attack emergency plan, including contacts, operation steps, backup IP resources, etc. Conduct regular simulated attack drills to ensure that team members are familiar with the handling process and shorten the attack response time.

To sum up, the solution to CC attacks requires a closed loop from identifying characteristics, locating the source, multi-layer protection to long-term monitoring. WAF rules and caching mechanisms should be configured in advance in daily operations. IP restrictions and CAPTCHA policies should be quickly enabled when attacks occur, and protection parameters will be continuously optimized and monitoring alarms will be improved afterwards. Only by combining technical means with management processes can we minimize the impact of CC attacks on business and ensure the stable operation of the website. I hope this introduction can help you establish an effective defense system.