Cloudflare frequently intercepts the tcp network detection of itdog.cn

Itdog.cn is the network diagnostic platform with the largest number of users in China. I found that when using the tcp tool to continuously detect the cloudflare network, cloudflare will intercept the detection nodes in Chinese Mainland of itdog. TCP requests will no longer respond to many nodes (icmp will not be affected). During the interception of tcp, all products under the entire cloudflare network will no longer respond to the tcp requests of the itdog detection point.

Does Cloudflare impose stricter restrictions on certain IP addresses?