At three o'clock in the morning that day, my cell phone was vibrating like a life preserver. I struggled to grab my phone, and on the screen was a series of alarm screenshots sent by my operation and maintenance brother and a voice with a sobbing tone: “Brother, the traffic is blowing up, the entrance is all red, and the business can't hold out any longer.”
I instantly sobered up and rushed to my computer. Logging into the console, into the eyes of a nearly straight line of peak traffic, not a common CC attack that slow climb, but like a sword straight into the heart - typical of theUDP FloodThe
That night, our traditional hardware firewalls like paper mache, millions of garbage messages per second to the bandwidth blocked the water, the real business requests can not even squeeze into the door. From that moment on, I completely understand that, in today's network environment, if your “high security” is only for HTTP/HTTPS, it is like only installing a security door to the front door, but the backyard fence torn down a clean.
UDP attacks, can be said to be the most “rogue” in the family of DDoS attacks, the most “unethical” one.
It doesn't even play the polite game of three handshakes with you. Attackers spoof massive amounts of UDP messages that are unceremoniously slammed into your server ports like garbage.DNS protocol,NTP protocol,SSDP protocolEven normal game ports are a springboard or target for this attack. Your server has to spend a lot of resources to deal with these meaningless “greetings”, parsing, responding, or waiting for a connection timeout that doesn't exist.
What is more disgusting is that the traffic manufacturing efficiency of this attack is extremely high, a small console can easily hit dozens or even hundreds of Gbps of traffic, the cost is low to outrageous. I have seen too many companies, spend a lot of money to buy the nominal hundreds of G defense “high defense”, a pure UDP Flood immediately encountered the original form, because their defense system may still rely on the bottom of the session state detection, and UDP flooding is precisely stateless, directly bypassed.
So, what really “ignores” UDP attacks?Anti-DDoS Servers?
It is definitely not the simple “turn on protection” button in your control panel. After so many years of fighting with the black industry chain, I found that a set of three-dimensional, from the edge to the core of the defense strategy, is the business of the life-saving straw. Expecting a single device or a single algorithm is pure self-deception.
The first line of defense has to be the operator's traffic cleaning center. This is equivalent to setting up a checkpoint right at the entrance to a national highway. A truly reliable high defense service has an IP address segment that is connected to the operator's cleaning node. When abnormal traffic (especially UDP torrents) is detected, the traffic does not rush directly to your server, but is pulled to these distributed cleaning centers.
Here deployed specifically for the stateless flood cleaning equipment, they through the characteristics of the analysis, rate limiting, fingerprint learning and other technologies, in the tens of thousands of network traffic, like a gold mine to sieve out the normal packets. You must not believe those who say “local firewall hard resistance” nonsense, in front of hundreds of G UDP flood, any single point of equipment bandwidth interface and computing power is a mantis.
The core advantage of a cleansing center is its “bandwidth hinterland” and dedicated hardware, which cannot be matched by a local server room in any way.
The second line of defense is smart routing with black hole mechanisms. Cleansing is not foolproof, and there are always extremes. When the attack traffic exceeds a predetermined threshold of terror that threatens the stability of the entire underlying network (e.g., the T-level), a responsible operator will activate the “black hole routing”.
Simply put, it's a direct message to routers around the world, at the very top of the network, “All data occurring at this IP address, please throw it directly into a black hole and don't pass it on.”
It sounds cruel, like giving up the servers, but in reality it's a heroic move to protect the thousands of other users in the server room from crippling the network infrastructure.
A good high defense service provider has a very high black hole trigger threshold and can provide real-time black hole status query and fast unblocking services. I have cooperated with some service providers, such as 08Host, in this piece of strategy is very transparent and flexible, their high defense IP rarely go to the whole network black hole this step, because the front cleaning capacity to give a large enough, which allows us to operate and maintain the staff have a bottom.
External defenses alone are not enough, but local server “fine-tuning” is critical. Many operations brothers ignore this point.
For UDP services, reasonable local configuration can effectively reduce the pressure of residual attacks. For example, for non-essential UDP services, firmly close ports. For UDP services that must be open (e.g., DNS, gaming), be sure to rate-limit them at the operating system level. iptables, or the more modern nftables, will do the trick under Linux.
These rules are like adding flow-regulating valves to each UDP service window of the server, which can't withstand a tsunami, but can prevent localized congestion formed by leakage even after cleaning.
Thinking at the architectural level is what is fundamental to long term success. My current principle is:Complete separation of core business from external servicesThe
Deploy UDP applications that are prone to attacks (e.g., game battlesuits, voice relays, DNS resolvers) behind true high defense IPs, or even use high defense servers alone. And the core assets, such as database, internal API, and management backend, are placed in another private network segment without any external ports, and communicate with the front-end high-defense server through a dedicated line or VPN.
In this way, even if the front-end UDP flood, at most, only affect that part of the external services, core data and internal business does not change. These days, even the CDN have to “prevent teammates” (meaning to prevent certain unreliable third-party services become the source of the attack), their own architecture and then do not do a good job of isolation, it is simply a gamble of luck.
When choosing a high defense server, don't just look at that total defense value number anymore. You have to ask like a detective:“What is your cleaning strategy for UDP Flood? Are the cleaning nodes distributed? What is the threshold for triggering a black hole in G. How long does the unblocking process take?” If the other party is evasive or only shows you a flashy PDF, then you can basically turn your head and leave.
The real ability, reflected in the technical details and operation and maintenance processes. I experienced a 300G+ level hybrid attack (UDP-based) that lasted more than 40 minutes, and the high-defense IPs used at the time relied on multi-center cleaning and flexible traffic scheduling to carry over the business in addition to slight fluctuations in latency, almost no packet loss. That kind of feeling after the robbery, than any advertisement can better illustrate the problem.
At the end of the day, there is no silver bullet for cybersecurity. “Ignoring” an attack does not mean that the attack does not exist, but that your business system is robust enough to treat it as background noise and no longer pose a substantial threat. This requires your defense system like an onion layered, from the carrier's backbone network cleaning, to intelligent routing scheduling, to the server's local granular control, and finally, the depth of the decoupling of the business architecture.
Spending money and energy on such a three-dimensional defense system, especially to ensure that it is optimized for UDP, a “low-cost killers”, is to run on the digital road for your business, equipped with a power, armor, strong engine.
It's only when the alarm goes off again that you can calmly take a sip of coffee, look at the easily defused spike in traffic on your protection statement, and muse, “That's it?”