HTTP/HTTPS Intercepting Proxy for Banking Integration Debugging
A leading Romanian retail bank
Why It Exists
Debugging integrations between the bank’s self-service modules and partner systems (CRM, OTP, OCR, core APIs) often requires seeing the exact bytes on the wire, including over TLS. This gateway/proxy tooling exists to intercept, inspect and replay that traffic during development and testing.
What We Built
Two complementary pieces. A compact, self-contained do.py, a multithreaded TCP forwarding proxy (~90 lines) that parses incoming HTTP requests, resolves target host/port, and relays bytes between client and upstream, useful for quick local tunnelling and inspection. Alongside it, an integrated proxy2 toolkit (with proxy2.py, a https_trasparent.py transparent-mode variant, a setup_https_intercept.sh helper and examples) for HTTPS man-in-the-middle interception, generating/installing a CA so encrypted banking traffic can be decoded and examined during testing.
Technologies & Approach
Pure-Python sockets and threading for a zero-dependency forward proxy, plus a transparent HTTPS-intercept setup for TLS inspection. Lightweight and scriptable by design, so it can be dropped into any dev environment without heavyweight tooling.
Outcome / Impact
Provided a practical, dependency-free way to observe and troubleshoot the request/response flows between SSS apps and their dependencies, speeding up integration debugging across the self-service banking suite.
Capabilities Demonstrated
- HTTP/HTTPS traffic interception and inspection
- Transparent TLS man-in-the-middle for controlled testing
- Lightweight, dependency-free networking tools in Python
- Practical integration-debugging tooling for complex back-office stacks