I don’t know if I used a VPS host with a high configuration before, or if there is a problem with the performance of the newly moved Alibaba Cloud Hong Kong VPS host. In short, every time I dig the site at night, the host becomes unstable and the system load suddenly becomes high. suddenly low. Using server log analysis tools: ngxtop and GoAccess, you can also find out that some IPs are constantly scanning server ports and WP background.