Network traffic inspection has always involved tradeoffs between visibility and performance. Traditional methods like man-in-the-middle (MITM) proxies require certificate management and introduce latency. Q.Tap, an open-source eBPF-based tool, aims to solve these challenges by providing visibility into encrypted traffic without the performance penalties.
How Q.Tap Works
Q.Tap leverages eBPF (extended Berkeley Packet Filter) to attach to TLS/SSL functions in the Linux kernel, intercepting data before encryption and after decryption. This approach allows developers and security professionals to see unencrypted traffic without modifying applications, installing proxies, or managing certificates. The tool operates out-of-band with minimal overhead, avoiding the latency issues common with MITM solutions.
For OpenSSL-based applications, Q.Tap scans binaries for TLS symbols and attaches eBPF probes to functions like SSL_read and SSL_write. This works for both dynamically linked libraries and statically compiled binaries, giving it broader coverage than many alternative solutions.
Language Support and Technical Challenges
While Q.Tap's open-source version primarily focuses on OpenSSL, the community discussion reveals that support for other languages and runtimes varies. Go support exists but isn't yet open-sourced, requiring special handling due to Go's static linking approach.
We have Go support, but it is not open sourced yet. Go is a bit more complicated but we were able to get it after some cave diving in the ELF formats... because Go is statically linked, we need to pull several different offsets of the functions we are going to hook into.
The developers have addressed optimization challenges by building custom binary utilities focused on fast symbol recognition rather than comprehensive debugging information. They've also implemented caching to avoid rescanning frequently used binaries and shared libraries.
Q.Tap Requirements
- Linux with Kernel 5.10+ with BPF Type Format (BTF) enabled
- eBPF enabled on the host
- Elevated permissions (sudo on host or specific Docker container settings)
Q.Tap Use Cases
- Security auditing
- Debugging network issues
- API development
- Troubleshooting third-party integrations
- Learning and exploration
- Legacy system investigation
- Validation testing
Development Prerequisites
- Linux (kernel 5.8+)
- Go 1.24+
- make
- clang14
- clang-tidy (optional)
Advantages Over Traditional Methods
Unlike MITM proxies or tools that require environment variables like SSLKEYLOGFILE to be set before application startup, Q.Tap can be attached to running processes. This makes it particularly valuable for troubleshooting production issues without restarting services. The ability to see encrypted traffic without adding latency addresses a significant pain point for developers debugging network communications.
The tool also provides rich contextual information beyond just the decrypted content, including source/destination details, bandwidth usage, SNI information, container metadata, and even Kubernetes pod and namespace information when applicable.
Security Considerations
As with any tool that decrypts traffic, Q.Tap raises security concerns. The developers emphasize that Q.Tap runs exclusively on your nodes, giving you control over what it captures and where that data goes. The eBPF verifier provides security guarantees that prevent arbitrary memory access.
For organizations with strict compliance requirements, Q.Tap offers configuration options including disabling TLS inspection entirely while still providing connection metadata. The paid offering from Qpoint.io provides additional security features and a control plane for dashboards and alerting.
Limitations and Future Directions
Q.Tap currently has several limitations. It requires Linux with Kernel 5.10+ and eBPF support, along with elevated permissions. Some commenters noted that uprobes can add latency through context switches, though the developers claim this is statistically insignificant compared to MITM proxies.
The tool also doesn't currently support all runtimes and languages equally. While the commercial version supports JVM, Go, and NodeJS, with Rust support in development, the open-source version has more limited coverage. Additionally, Q.Tap doesn't currently work on non-Linux platforms, though the developers expressed interest in exploring Microsoft's eBPF implementation for Windows support.
For those interested in trying Q.Tap, the project offers a quick demo mode that can be run with a simple curl command, making it easy to see the tool in action before committing to a full installation.
Reference: Q.Tap