Just took over a financial project, the boss patted his chest and said, “We have this volume, who will come to fight ah”, the results of the third day on the line, directly hit to the self-closed. Three o'clock in the morning received an alarm text message, the entire business cluster completely paralyzed, the traffic peak soared to 200 times the usual - this time to understand, high defense CDN is not optional, but a life-saving straw.
These days DDoS attacks have long been industrialized, just find an underground market, 500 bucks can buy 24 hours non-stop G-rated traffic attacks. You think a set of Cloudflare free version will be able to rest easy? I'm not sure if I'm going to be able to do that, but I think I'm going to be able to. Last year, an exchange used a cheap CDN, was TCP flood penetration, the attacker even arrogant to the official website to hang blackmail message. Never believe those “unlimited defense” false propaganda, really encountered a huge traffic impact, many service providers first reaction is to give you to do empty route.
The real experience of the actual battle know that to deal with T-level traffic attacks must be layered defense strategy. Just like the ancient city defense, the outer city fell and the urn, the urn broke and the inner city. I tested and found the most reliable structure is: intelligent scheduling layer → edge cleaning layer → source station protection layer, three-layer linkage in order to play a perfect defense.
It's the smart scheduling of the first level that is most people's blind spotThe first thing you need to do is to get a good cleaner node. Many teams think that if they buy a good cleaning node, everything will be fine, but they don't know that if the scheduling strategy doesn't work, the attack traffic can directly overwhelm the link back to the source. Last year, when I used CDN5's global load balancing, I set up an ASN-based traffic scheduling policy to automatically schedule traffic from suspected attack source areas to high-defense nodes:
This set of rules helped me block 70% tentative attacks, especially those requests coming from the ASN segment of a typical botnet, which were diverted directly to the high defense cluster for processing. Interestingly, the attacker later changed to use the cloud vendor IP segments to launch attacks, I added additional detection rules based on HTTP header characteristics - Dao tall foot high devil ah.
Technology selection for the edge cleaning layer directly determines the defense ceilingThe first thing I'd like to say is that I don't know how much I can do. Don't look at the CDN vendors are blowing their own how many T cleaning capacity, really to the pressure test when the performance is very different. Last year, when I did the vendor selection, I pulled out CDN5, CDN07 and 08Host to do the real traffic test:
Simulating a 500,000 QPS per second HTTP Flood attack, CDN07's CPU load suddenly soared to over 90%, and the latency deteriorated from 35ms to 800ms; 08Host directly triggered the meltdown mechanism, and jumped CAPTCHA for normal users as well; on the contrary, CDN5's performance amazed me - Their dynamic fingerprint detection can actually keep the normal business latency stable within 50ms.
The key difference is the cleaning algorithm. Traditional threshold-based detection (e.g., triggered when the number of requests per second exceeds the limit) is too easily bypassed, and advanced attacks now simulate normal user behavior. The best solution is to use machine learning models to do behavioral analysis, such as detecting mouse movement tracks, API access sequence anomalies, and so on. This is why the professional high-defense CDN is 3 times more expensive than the cloud vendor's own protection - people really hit the money on the algorithm.
Elastic bandwidth is the ultimate physical defenseThe first thing I'd like to say is that I don't want to be a part of it. Say what algorithm what strategy, encounter T level attack ultimately look at the bandwidth hard power. But buy fixed bandwidth is to pay IQ tax, usually 95% time idle burning money. I have compared three elastic programs:
CDN5 adopts the “guaranteed + burst” mode, pay 2G monthly base fee, burst bandwidth according to $0.12/GB billing. Tested to be hit when the capacity can be automatically expanded to 2T, settled down a large-scale attack defense cost of about $ 3,000.08Host engaged in bandwidth pooling program, the joint 100 customers to share the 10T cluster, usually cheaper, but encountered a number of customers at the same time when the attack may be resources scramble. The most pitiful is a well-known cloud vendors, the contract is written in the “elastic capacity expansion”, really hit when you have to manually lift the work application - attackers will not wait for you to go through the approval process!
It's the source station cloaking that's the killer move that many people ignore. I've seen too many teams buy a high defense CDN but expose the source station IP fiasco. Attackers get the real IP through historical DNS records, SSL certificate sniffing, and even mailbox server reverse lookup, directly bypassing the high defense to penetrate the source station. You must do the whole link to hide:
This set of combinations of punches down, last year we carried a record 1.2Tbps attack, business latency increased only 20ms. after the attack group in Telegram spit: “this CDN5 node with the onion like, peel off a layer there is a layer”.
Now let me choose the model, I will prioritize three points: global scheduling capabilities (at least 30 cleaning nodes), flexible billing reasonableness (can not sudden skyrocketing bill), the degree of automation of the API (whether it can be docked to the self-built monitoring system). Recently tested CDN07 in Asia-Pacific performance is good, but the European node latency is high; 08Host cost-effective for startups, but the stability of the large traffic to be observed.
Finally said a solid: no 100% security system, high defense CDN just raise the cost of attacks to the other side can not afford. We now set the defense threshold is 800Gbps - not to prevent larger, but measured the cost of attackers to rent this level of botnet has exceeded the value of our business losses. Security is essentially a matter of economics, don't forget to do the math.
