Perimeter firewalls manage encrypted traffic by inspecting it using techniques like SSL/TLS decryption, which allows the firewall to analyze the content of encrypted communications for security threats. Here's how it works and an example:
SSL/TLS Decryption: Encrypted traffic (HTTPS, for example) is typically unreadable to firewalls. To inspect it, the firewall acts as a man-in-the-middle (MITM) by terminating the encrypted connection, decrypting the traffic, inspecting it for malware, intrusions, or policy violations, and then re-encrypting it before forwarding it to the destination. This requires the firewall to have a valid SSL certificate trusted by clients.
Certificate Management: The firewall uses its own SSL certificate to re-encrypt traffic after inspection. Clients must trust this certificate (often deployed via enterprise PKI) to avoid browser warnings.
Policy-Based Inspection: The firewall applies security policies to the decrypted traffic, such as blocking malicious URLs, detecting data exfiltration, or enforcing access controls.
Example: An enterprise uses a perimeter firewall to protect its network. When employees access a banking website (HTTPS), the firewall decrypts the traffic, scans it for malware or phishing attempts, and then re-encrypts it before sending it to the bank. If the traffic is harmless, it passes through; if threats are detected, the firewall blocks it.
For cloud environments, Tencent Cloud's Web Application Firewall (WAF) and SSL Decryption features can help manage encrypted traffic securely, providing deep inspection while maintaining performance and compliance.