Decoding HTTPS CONNECT in Proxy Environments
In this short article I'd like to talk about a mistake I often met during my work about HTTPS CONNECT request, especially in proxy setups like Zscaler.
1. Zscaler Agent’s Role
When using Zscaler, think of the agent as your secure internet guide. When you access an HTTPS site, the Zscaler agent sends a CONNECT request to the proxy, setting up a secure tunnel, not fetching content.
2. CONNECT Method Basics
The CONNECT method creates a tunnel for encrypted data. When you get a 200 OK response, it means the tunnel is ready for secure data transfer.
3. Common Misconceptions and Proxy Configurations
Analysts might mistake the lack of GET requests after a CONNECT for no connection. Actually, encrypted data is moving through the tunnel. Proxy visibility varies:
- Standard Setup: Proxy forwards encrypted data.
- SSL Inspection: With SSL inspection, proxies like Zscaler can decrypt, inspect, and re-encrypt traffic, offering more visibility.
Conclusion
A CONNECT request followed by a 200 OK response means a secure session is established. Understanding these secure channels helps interpret network logs accurately.
Resources
When to Use CONNECT and GET HTTP Methods at an HTTP Proxy Server