Recently, a customer came to the door, said their video platform playback interface is always lagging, the user complaints burst, a check logs, good guy, CC attack traffic like a flood over, directly to the server dry lying. I found that the actual test, this year's video site is really a disaster area, the attackers pick playback interface to start, because the traffic here is large, consume more resources, casually come to a CC attack can make the CDN bandwidth burst table, the service provider bill fly up, the user experience to the bottom of the valley. Do not believe that the so-called “universal protection” program, the specificity of the video scene determines that you have to use the precise defense, otherwise it is a waste of money but also beaten.
When it comes to CC attacks, it's not as brute force as DDoS, but rather simulates normal user requests and frantically brushes interfaces, such as frequent calls to video playback URLs, resulting in server resources being exhausted. Video playback interfaces are especially vulnerable because they usually involve large file transfers, authentication checks, and session management, and attackers can easily trigger high concurrency by simply using scripts to batch requests, sending CPU and memory soaring. I have encountered a platform, the attack peak QPS rushed to more than 100,000, normal users simply can not load the video, CDN cache are broken, the back-end source station directly 504 timeout. This problem is analyzed, the core lies in the lack of rate limitation and intelligent verification of the interface, coupled with the CDN configuration is too general, not for the video path to do the refinement of the rules.
For the solution, I recommend using a high-defense CDN combined with custom WAF rules to achieve accurate defense. First of all, you have to isolate the video playback interface, such as all `/api/video/play` path requests are handled separately, and set up strict frequency control on the CDN. CDN5, for example, they have a “smart CC protection” function, I have tested, can be based on IP, User-Agent and Referer to do multi-dimensional analysis, automatically block abnormal requests. Configuration, I added a rule in the console: for the `/video/` path, more than 50 requests per second will trigger human verification, if it is the API interface, then directly limit the flow to 10 times per second. At the code level, you can use Nginx as an aid, such as deploying such a configuration at the source site:
What this configuration means is to enable request rate limiting for the video playback interface, with a maximum of 50 requests per second per IP, 20 allowed in bursts, and then rejected outright if exceeded, to avoid queue stacking. I also tried a similar program on CDN07, their advantage is that there are many global nodes, low latency, especially suitable for video business, but the configuration has to be manually tuned - for example, set up geo-blocking, only allow access to a specific region, to reduce the overseas attack traffic. Data comparison, I tested CDN5 and 08Host, CDN5 in the bandwidth expansion is more flexible, the attack can automatically expand the capacity of the elasticity, the cost is controllable; 08Host is better than in the cost-effective, basic protection is free, but the advanced features have to add money. In practice, I combined the CDN WAF and self-built rules to suppress the attack traffic by more than 90%.
Also, don't ignore the old tricks of CAPTCHA and token validation. For the video playback interface, I often add a simple token verification, for example, the request must be with a dynamically generated token, the validity period to release. Code example implemented in Python Flask words:
In this way, it is very difficult for attack scripts to fake requests in bulk, because the token needs to be generated in real time. I found that although this method increases the delay, but the defense effect is great, the user is almost senseless. Also, CDN configuration remember to open the real-time monitoring and alerts, such as setting the QPS threshold, exceeding the limit on the email or SMS, to facilitate timely response. Spit it out, some service providers marketing blowing on the sky, really out of the problem of the work order slow, so do not just look at the price of the CDN, you have to look at the after-sales - like CDN07 24/7 technical support is quite reliable, my last emergency they responded to a 10-minute.
To summarize, the key to video high-defense CDN defense against CC attacks is precision and layering: isolated interfaces, rate limiting, intelligent verification, and then with the advantageous features of the CDN service provider. From my experience, CDN5 is suitable for high-traffic scenarios, and 08Host is suitable for teams with limited budgets, but no matter who you choose, you have to customize the rules, or else it's just paper. Finally, a reminder, the industry is changing fast, the attack method is renovated every day, regular review protection strategy is the king - do not wait to be hit before regretting not to prepare early.
