Which Online Blocked Website Detection Tool Is Best? 5 Practical Connectivity Testing Platforms

Webmasters running overseas servers, cross-border e-commerce, or foreign trade websites have almost all encountered this frustrating situation: the backend shows the server is running fine, overseas access is lightning fast, but users on certain domestic provinces or specific ISP networks frequently report "page won't load" or "connection timeout."

This typical "partial or full network connectivity anomaly" is often caused by the domain or server being blocked by the Great Firewall. In such cases, blindly restarting the server or changing configurations won't solve the problem at all. To quickly identify the root cause, using online detection tools with nationwide multi-node concurrent probing capabilities is currently the most efficient troubleshooting method.

Normally, if you run concurrent tests on different tools and find that overseas nodes are all green, while domestic HTTP/HTTPS requests return connection refused or timeout in large numbers, and Ping nodes are partially reachable, you can basically conclude that the domain is experiencing SNI/TCP blocking or DNS pollution. If even ICMP Ping is all red with packet loss on domestic nodes, it's highly likely that the server IP address has been directly banned.

1. What Are the Common Network Issues?

Before directly running tools, it's necessary to understand several common types of network blocking. Many beginners easily mistake line jitter or slow local DNS resolution as "being blocked." Understanding their performance differences will give you confidence when reading detection reports:

• DNS Pollution: Network nodes deliberately return fake IP addresses (such as resolving to 0.0.0.0 or invalid overseas IPs), causing users' browsers to be unable to find the real server.

• TCP/SNI Blocking: The domain resolves to the correct IP, and ICMP Ping works, but as soon as you access the webpage via HTTPS (sending SNI domain information), the connection is instantly cut off or forcibly reset (RST). This is currently the most common interception method.

• IP Ban: The specific IP of the target server is directly blacklisted, causing all ports (80, 443, Ping, etc.) of that IP to be unreachable on domestic networks. No matter what new domain you bind, as long as it points to that IP, it will fail.

The core advantage of online connectivity testing platforms is that they can dispatch nodes from telecom, Unicom, Mobile, and overseas locations across the country within seconds to initiate access tests simultaneously, eliminating misjudgments caused by local ISP failures.

2. In-Depth Review and Recommendation of Popular Online Blocked Website Detection Tools

1. chahu (Teapot Speed Test)

Official Website: https://www.chahu.com/block

chahu is a network diagnostic tool that has gained a good reputation among运维 and webmaster circles in recent years. In terms of connectivity troubleshooting, its blocked website detection feature is quite solid. After entering a domain, the system will call concurrent nodes from major provinces across the country within seconds for testing.

Key Highlights:

• Detailed Blocking Distinction: Clearly distinguishes between DNS resolution failure, TCP handshake interruption, or HTTPS/SNI-level blocking, avoiding vague judgments.

• Full-Link Visualization: Combined with route hop count, packet loss rate, and latency display, making it easy to determine whether the problem lies at the backbone network exit or provincial local nodes.

• Comprehensive Risk Assessment: In addition to connectivity tests, it also integrates domain interception and security status checks, making it suitable as the first stop for daily troubleshooting.

Applicable Scenarios:

• Sudden Website Connectivity Troubleshooting: When receiving reports from users in specific domestic provinces or ISPs (Telecom/Unicom/Mobile) that "the website won't open," quickly locate the affected specific regions and lines.

• Precise Determination of Blocking Type: Quickly confirm whether the domain is experiencing DNS pollution, TCP/SNI blocking, or a pure server IP ban.

2. ITDOG

• Official Website: https://www.itdog.cn/py/

ITDOC is quite popular among veteran webmasters, mainly because it has a large number of domestic nodes.

• Key Highlights: The "China map color block diagram" generated after running tests is very useful. Provinces with normal node responses show green, lagging ones show yellow, and if unreachable, they turn red. If you run a test and find that the domestic map is largely red or even all red, while overseas nodes are all green, you can be almost certain that the domain is blocked.

• Applicable Scenarios: Suitable for testing node responses across the country, or checking the coverage and acceleration effect of a newly configured CDN in different provinces.

3. Boce (拨测)

Official Website: https://www.boce.com/wall

Boce is an enterprise-level comprehensive monitoring platform, and its blocked website query and pollution detection modules are also frequently used.

• Key Highlights: Its advantage lies in node coverage that includes not only the three major ISPs but also niche lines like education networks and Great Wall Broadband. Additionally, if you have a bunch of domains to check, it supports batch import queries, saving you from manual entry and improving efficiency.

• Applicable Scenarios: Suitable for batch risk screening before domain transactions, as well as simultaneous detection of WeChat and QQ interception status.

4. GreatFire.org

Official Website: https://zh.greatfire.org/

Unlike the previous tools that focus on "real-time connectivity speed," GreatFire specializes in historical data recording and continuous statistics of network blocking behavior.

• Key Highlights: You can view the trend of a domain's blocked ratio over the past months or years. By comparing crawl results from domestic and overseas nodes, it provides long-term blocking judgments.

• Applicable Scenarios: Suitable for confirming whether a domain is a specific target that has been blocked for a long time.

5. Ping.pe

Official Website: https://ping.pe/

Developed by the backend team of a well-known overseas VPS provider, this tool has a minimalist interface but is highly targeted. Nodes are evenly distributed across North America, Europe, Asia, etc.

• Key Highlights: Specifically tests ICMP/Port connectivity for a given IP or domain. The result list clearly shows "overseas nodes all green (OK), mainland China nodes all red (Failed)" for easy comparison.

• Applicable Scenarios: When you're unsure whether the domain is blocked or the newly rented overseas server IP is banned, this tool is the most intuitive to use.

3. Comparison of Mainstream Testing Platforms

4. Practical Response Strategies After Confirming a Website Is Blocked

If after multiple tests with the above tools, you confirm that the website is indeed blocked, you can take countermeasures based on your business situation:

1. Thoroughly Investigate and Clean Website Content: Many websites get blocked because they are hacked, defaced, or contain prohibited content. The first step is to check server files and databases, and fix security vulnerabilities, as this is a prerequisite for all subsequent repair work.

2. Change to a New Domain and IP Address: If you encounter severe DNS pollution or a global IP ban, the most direct solution is to switch to a clean new domain and change the server IP. If conditions permit, re-register the new domain with search engines.

3. Use a Compliant Domestic CDN or High-Defense Node: For some SNI blocking, if the website has an ICP filing, you can switch the domain back to a domestic data center and use a compliant CDN, leveraging the node's normal resolution to transition, which usually restores access.

4. Check SSL Certificates and Standard Port Settings: In some cases, SNI interception is triggered by abnormal certificates or non-standard ports. Using a standard SSL certificate issued by a well-known CA and using the standard port 443 can reduce the risk of false blocking to some extent.

Website connectivity anomalies are an unavoidable challenge in operations, but when you encounter a site that won't open, don't panic and speculate. First, run a node scan with Chahu to quickly identify whether it's DNS pollution, SNI blocking, or a pure IP ban. Then, based on the specific blocking type, take measures such as cleaning up prohibited content, changing IP/domain, or using protection services. This is the most reliable approach. It's recommended to bookmark commonly used detection tools in your browser so you can diagnose immediately during sudden network anomalies.

Related Q&A

Q: If a detection tool shows that a domain is blocked, is the result accurate? Could it be a false positive?

A: Online detection tools generally do not produce false positives. These tools work by simultaneously dispatching multiple nodes from domestic Telecom, Unicom, Mobile, and overseas to initiate access. If domestic nodes show large-scale timeouts or connection refusals, while overseas nodes are all normal, you can basically conclude that blocking has occurred. However, note that occasional anomalies in a single province or ISP node could be due to local network fluctuations or node issues. It's recommended to cross-verify with multiple tools before making a judgment.

Q: After a website is blocked, what's the fastest way to restore it?

A: The fastest way is to change the domain and server IP. There is basically no appeal channel for DNS pollution or IP bans, and waiting for automatic unblocking is unrealistic. Register a new domain, point it to a new server IP, and set up 301 redirects to transfer traffic from the old domain. This usually restores access within a few hours. If the website has an ICP filing, migrating the domain back to a domestic data center and using a compliant CDN is also an option.

Q: Are there any warning signs before a website gets blocked? Can it be prevented in advance?

A: There are several obvious warning signals. For example, a sudden significant drop in website traffic, sporadic reports from users in a few provinces that the site won't open, or frequent alerts from third-party monitoring platforms about connectivity anomalies in a certain region. For prevention, regularly scan the domain status with detection tools, check the server for malware or injected malicious pages, update SSL certificates promptly, and change non-standard ports back to 443 to reduce the probability of being falsely blocked.

Q: If a detection tool shows that the website is inaccessible only on mobile networks, while other ISPs are normal, is it blocked?

A: This situation is unlikely to be blocking; it's more likely an interconnection issue between ISPs or a routing failure on a specific line. A real block usually covers all ISPs, not just one. It's recommended to use MTR or route tracing tools to see where the packet loss occurs. If it's a backbone network exit issue, just wait for the ISP to fix it; there's no need to rush to change domains.

Q: Can CDN bypass the firewall?

A: It depends. If only the domain is blocked by SNI, using an overseas CDN like Yewsafe with proxy mode enabled and pointing the domain to the CDN's IP has a certain probability of restoring access. However, if the IP is banned, CDN won't help; if the origin IP is exposed, it will still be blocked. Additionally, if the website primarily targets domestic users, the safest approach is to obtain an ICP filing and migrate back to a domestic data center.