Basic principles to be followed in firewall design

1. Traffic from inside to outside and from outside to inside must pass through the firewall.

2. Only the business flow approved by the local security policy can pass through the firewall.

3. Try to control external users' access to the intranet and strictly limit external users' access to the intranet.

4. Be transparent enough to ensure the circulation of normal business.

5. Have the ability to resist infiltration attacks and strengthen recording, auditing and early warning.