Is the protection capability of the DDoS protected cloud servers in Los Angeles truly reliable? Can they maintain service stability under real attack traffic? Stress testing is a direct way to verify this, but improper operation may violate the terms of service or affect others, leading to server bans. Therefore, the core principle of stress testing is "simulating real threats under secure, authorized, and controllable conditions."

Preparation before testing is more important than the test itself. The first step, and absolutely indispensable, is to carefully read the service provider's terms of service and formally communicate with them. Most reputable DDoS protected service providers explicitly prohibit users from launching DDoS tests on their networks themselves, unless using their official "stress testing platform" or submitting a written application in advance specifying a testing time window. Blindly testing can result in service suspension at best, and legal liability at worst. When communicating with customer service, clearly state your testing objectives (e.g., verifying 50Gbps SYN Flood protection), the desired testing time period (usually recommended during off-peak hours, such as late night or early morning in Los Angeles), and the range of source IPs for the test (if you are building your own test nodes). Obtaining explicit permission is a prerequisite for security testing. The second step is backup and monitoring setup. Before testing, be sure to perform a complete backup of all critical data and configurations on the server. Simultaneously, you need to set up a monitoring system to observe the server status in real time during the test. Basic monitoring commands include observing CPU, memory, and disk I/O, while for high-defense testing, network traffic and connection counts are of paramount importance.

# Real-time multi-faceted monitoring (It is recommended to run using tmux or different terminal windows separately)

# 1. Comprehensive system monitoring (can use htop or glances)

htop

# 2. Real-time network traffic monitoring (view external network cards, such as eth0)

iftop -i eth0

# 3. Real-time TCP connection status statistics

watch -n 1 'netstat -n | awk '\''/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'\'''

# 4. Brief overview of system performance

vmstat 1

After completing the preliminary preparations, the next step is to design the test plan. Stress testing of high-defense servers is usually divided into two levels: legitimate business traffic stress testing and simulated attack traffic testing. The former tests the server's carrying capacity under normal business peaks, while the latter verifies the effectiveness of the defense system. For legitimate traffic testing, conventional stress testing tools can be used, such as `wrk` or `Apache Benchmark (ab)` for web servers. The purpose of this test is to identify the server's performance bottlenecks under normal conditions, such as the level of concurrent connections at which the application's response time spikes or begins to crash.

# Using ab to perform concurrent stress testing (legitimate traffic) on a web service

ab -n 100000 -c 1000 http://yourserverIP/

# Parameter explanation: -n Total number of requests, -c Concurrency level

Simulated attack testing, on the other hand, requires more specialized tools and must be conducted in a fully controlled and authorized experimental environment (such as an independent test cluster built by yourself or a partner). Never use any "stress testing service" found on the internet to attack your production server. Common simulated attack types include TCP SYN Flood, UDP Flood, and HTTP GET Flood. In your own testing environment, you can use tools like `hping3` and `MHDDoS` (for learning and research purposes only) to send massive amounts of specific types of data packets to the target server. The key to testing is not to "brute force" the server, but to observe the defense system's response: At what threshold (e.g., 10Gbps) does the attack traffic begin to be cleaned? During the cleaning process, are normal business requests (which can be continuously sent from another clean IP) affected? What are the latency and packet loss rate curves at the start, during, and end of the attack?

During the test execution, your role is that of an observer and recorder. You need to closely monitor several core dashboards:

1. The DDoS protection provider's console: This is the most important view. Reputable DDoS protection services provide real-time traffic charts, clearly distinguishing between "inbound traffic," "cleaned traffic," and "attack traffic." You will see that when the attack traffic reaches a certain threshold, "cleaned traffic" will remain stable, while "attack traffic" will be separately identified and separated.

2. Server internal monitoring: Observe whether the server's CPU and memory usage are within the normal range. An ideal high-defense scenario is that even with a large inbound traffic volume (e.g., under attack), the actual business traffic reaching the server's network interface card after external scrubbing is small, and server resource consumption should remain stable. If server CPU usage spikes abnormally, it may mean that some attack traffic has penetrated the defense, or that your application layer configuration (such as web server connection handling) needs optimization.

3. Business Availability Monitoring: Continuously conduct access tests on critical business pages on the server from multiple monitoring points globally (or your own different network environments), recording availability and response times. This directly verifies the ultimate goal of "high-defense"—ensuring uninterrupted business operations.

After the test, analysis and reporting are crucial. You need to compile all data from the test period: peak attack traffic, scrubbing trigger threshold, duration of business impact, peak server resource usage, etc. Based on this data, answer key questions: Did the defense meet the service provider's promised specifications? Was the scrubbing mechanism intelligent (can it accurately identify and allow normal traffic)? What was the delay from the start of the attack to the scrubbing taking effect? ​​Did the business experience any impact (were there any slight fluctuations or connection interruptions)? Based on the results, you may need to adjust the configuration of the server or application itself. For example, if testing reveals that a sudden surge in new connections can cause the web service to crash, you might need to optimize parameters such as `nginx`'s `worker_connections` and the system kernel's `net.core.somaxconn`.

Throughout the process, always keep the following red lines in mind: Never test targets that are not owned or authorized; never test DDoS protected lines without notifying the service provider; gradually increase the scale and intensity of the test, avoiding using maximum traffic from the outset; and be prepared to stop the test at any time. As an international hub, the Los Angeles data center has a complex network environment, and your test traffic may have unexpected cross-border impacts. Therefore, a successful stress test is the result of technical capability, meticulous planning, and rigorous communication.