What security problems may exist in the web server?

The following is a brief summary of common network problems:

DoS attack;

SQL injection;

CSRF；

XSS, etc.

General countermeasures:

Open the firewall

Escape input and output data, including special symbols;

Do not use concatenated SQL strings

Data validity detection;

Data flow monitoring;

Update security or high-risk vulnerability patches in time;

Token mechanism or verification code setting;

Refine file directory permissions, etc. ;

Online file type and content verification;

Horizontal authority management, etc.