1. Introduction
Many users encounter their overseas VPS IP being blocked for the first time and mistakenly think their server is down. However, in most cases, it’s not a problem with your machine—it's simply that the IP has been flagged by China’s Great Firewall (GFW), meaning it’s inaccessible from mainland China but still works fine abroad.
Let me explain this in simpler terms and provide you with solutions for dealing with this issue when it happens.
2. Who Blocked Your IP?
There are two main entities responsible for blocking your IP:
1. GFW (Great Firewall)
The GFW monitors cross-border internet traffic, analyzing your access behavior and protocol characteristics to determine whether it’s “suspicious” or “non-compliant.” If it is flagged, the GFW will block it.
2. Domestic ISPs (Telecom, China Unicom, China Mobile)
These ISPs follow the GFW’s blocking strategy. If they detect that a particular IP is involved in malicious activities or abnormal traffic, they will block it locally.
3. Why Did Your IP Get Blocked?
There are generally two types of reasons for an IP being blocked: you triggered the rules or you were mistakenly caught in the crossfire.
1. Suspicious Traffic Behavior
This is the most common reason for getting blocked. Examples include:
DDoS attacks or large amounts of abnormal traffic
Programs sending fixed-interval heartbeat packets, which are flagged as proxy/ circumvention traffic
High-frequency requests resembling web scraping or attacks
Too many long connections or very obvious traffic patterns
In these cases, your IP can be blacklisted for exhibiting behaviors perceived as risky or malicious.
2. Content or Historical Issues Leading to a Block
Sometimes, the reason is historical or related to content issues:
Your server might have previously hosted illegal or sensitive content
The IP range might have been used for malicious activities in the past
DNS pollution or poisoning might cause the real IP to be blocked
Your server might have been hacked and used to launch attacks, resulting in the IP being blocked by the ISP
In some cases, it’s just bad luck and you get caught in the crossfire.
3. Attack on the Datacenter
If your datacenter is under a large-scale attack, the ISP may temporarily block the entire IP range to protect the network, which could affect your server’s IP as well.
4. What to Do If Your IP Is Blocked?
Quick and Direct Solutions
1. Change to a New Public IP (Most Direct Solution)
You can release your old IP on the cloud platform and request a new one. Most overseas providers make this process quite easy. However, be aware that if your traffic behavior is still problematic, the new IP could also be blocked.
2. Use a CDN to Hide Your Real IP (e.g., Cloudflare)
You can host your domain on Cloudflare and enable proxy mode (orange cloud icon).
With this, domestic users will see Cloudflare’s IP instead of your server’s IP, allowing access to your server even if the IP is blocked.
Advantages:
No need to change your server
Allows access to a blocked server in mainland China
3. Use High-DDoS Defense or Traffic Cleaning Services
Purchase high-defense IP services (e.g., from Alibaba Cloud, Tencent Cloud, or overseas providers).
These services will help filter out attack traffic and forward the legitimate data to your server.
This is ideal for businesses with frequent DDoS attacks, like APIs or other high-frequency services.
4. Use a Jump Host or VPN for Traffic Forwarding
You can use another overseas server to forward traffic to your blocked IP.
This is not a long-term solution but can work well in an emergency.
Long-Term and Stable Solutions
1. Automated IP Switching Architecture
Set up a system that can automatically switch IPs in just a few minutes, even keeping the session alive while switching.
This generally involves multi-cloud deployment (AWS, GCP, Azure) along with load balancing.
2. Traffic Obfuscation to Prevent GFW from Recognizing Your Traffic Patterns
Make your traffic look like regular HTTPS (TLS handshake characteristics)
Mimic normal browser behaviors, such as random packet sizes
Add "noise" traffic to confuse DPI systems
These techniques are effective for services frequently flagged as "suspicious" by the GFW.
5. How to Prevent Your IP from Getting Blocked Again?
1. Compliance and Security
Avoid hosting sensitive content
Regularly patch your server and update software
Set up firewalls and close unnecessary ports
Block brute force login attempts
2. Optimize Traffic Behavior
Implement rate-limiting on APIs and services
Add CAPTCHA or human verification where necessary
Avoid using high-risk protocols like UDP or ICMP
3. Redundancy in Your Architecture
Use multiple nodes, IPs, and ensure high availability
Employ Anycast and BGP multi-line routing
Implement smart DNS that returns different IPs based on user location to prevent one IP from going down
4. Domain-Level Protection
Enable DNSSEC to prevent DNS pollution
Force HTTPS for encrypted communication
Do not expose your real server IP publicly
Conclusion
When your overseas server IP gets blocked, it’s not just bad luck; it’s usually due to traffic behavior, attacks, or content-related issues triggering automatic blocking mechanisms. To avoid this, it’s essential to follow security best practices and traffic management guidelines, which will keep your server accessible and in compliance.