How to determine and resolve when a website domain is blocked by the firewall

Domain being blocked means a domain blocked by the Great Firewall【abbreviated as GFW】, also called the Chinese firewall or China National Firewall. Reasons a domain may be blocked may be that the website has too much illegal information or sensitive content, does not comply with domestic laws and regulations, or the domain itself contains sensitive words, or the website hosting used is overseas, or the overseas IP has sensitive reactionary information and is directly blocked. Once a domain is banned by GFW, there is no query or appeal channel. Although domain resolution is normal at this time, access will be connection reset, directly causing the website to be inaccessible.

1. National Firewall

The chief designer is Fang Binxing, former president of Beijing University of Posts and Telecommunications, hailed as the “father of the National Firewall”. Under this system, the state can block any illegal website outside mainland China, making them inaccessible from China—what we call a blocked domain. Generally speaking, the domain is blacklisted by the National Firewall, or the website IP is blacklisted by GFW.

2. Common blocking targets

① Illegal websites such as pornography, gambling, and drugs, and associated IPs.

② Websites with sensitive information such as political involvement and reactionary content.

③ The domain itself contains sensitive words.

④ There may be cases of mistaken interception.

3. Several manifestations of a domain being blocked by the Wall

(1) Blocked due to anti-fraud reasons

In this case, domain resolution is normal, but it cannot be accessed in some places, or individual networks cannot access it (for example, China Mobile cannot access it). A reset connection reset phenomenon may occur, or it may be hijacked to 127.0.0.1 or 0.0.0.0. It is currently known that Fuzhou, Fujian, and Quanzhou, Fujian, may intercept more websites that resolve overseas.

(2) DNS hijacking

More observant webmasters may find that sometimes when using China Telecom broadband to open a certain website, it will jump to other pages, or simply cannot be opened, and the domain cannot normally resolve to its own server address. This is very likely DNS hijacking, also called DNS pollution. This is also a means of GFW interception and blocking. This nature may be relatively serious, directly hijacking the domain, causing this domain to be unusable normally in China. There is no solution except changing the domain. To determine whether DNS pollution exists, you can go to http://ping.chinaz.com/ to check domain resolution. If it is detected that the domain resolution points to different IPs, and they all point to overseas addresses such as Facebook, twitter, Google, etc., it indicates that it has been directly banned by GFW, and you can only change the domain.

(3) Domain included in the GFW blacklist

When IP/DNS hijacking is ruled out, then the domain is blocked by the Wall.

Symptoms of a domain being blocked by the Wall: the domain can resolve normally, but accessing it produces a reset connection reset, and other websites on the server also cannot be accessed at this time. After a period of time, other websites become normal, but after accessing the blocked website, all are implicated and inaccessible. Testing by connecting through an overseas proxy shows it can be accessed normally. In this case, it can basically be determined that the domain is blocked by the Wall. Changing to a domestic filing for use will do; access to overseas [sites] all has to go through GFW filtering, while placing the website domestically eliminates this concern. Of course, you also cannot make a website with illegal or sensitive content information.

4. How to determine whether a domain is blocked by the Wall

1. Analyze through website access symptoms and compare through third-party tool detection.

As shown in the figure below, it resolves overseas, and all third-party detections show download abnormalities. This may be because the IP or domain resolves overseas and is blocked by the Wall. Switching to a domestic data center and filing will generally solve it.

As shown in the figure below again, most regions are hijacked to the local machine, but some places can access it. This is hijacking. It may be due to anti-fraud reasons, or because the domain contains related keywords, or due to content reasons. You can try consulting the anti-fraud center.

Blocked-by-Wall query address: https://www.boce.com/wall, www.17ce.com (check whether there is a download abnormality prompt in the detection node)

Pollution query address: https://www.boce.com/pollute 

Illegal interception query: https://www.110.cqqgsafe.com/ (The data is not necessarily complete, but if you find a record, try contacting the local anti-fraud center to appeal) 

5.Solutions:

(1) First ensure the website is legal and compliant, check website information, clean up sensitive content, and website content must comply with domestic policies and regulations.

(2) If resolving overseas is blocked by the Wall, move the website to the mainland, use a domestic server, and complete filing.

(3) If it is DNS hijacking pollution, there is no solution; change the domain.

(4) If filed and resolved to within China, but some regions are intercepted and cannot access, it may be due to anti-fraud reasons. You can try contacting the local anti-fraud department to appeal.

If you cannot determine it yourself, you can submit a ticket and we will detect and analyze the reason.