Stata Net Install ↔ OS TLS/DNS Stack: How are certificate validation errors surfaced?

Direct answers

What diagnostic text does Stata emit for certificate failures? A generic message such as cannot connect or host not found. The underlying TLS alert (e.g., "certificate verify failed", "certificate expired", "hostname mismatch") is not surfaced.

Is there a documented way to inspect the TLS handshake or certificate chain from inside Stata? No. Stata provides no command, option, or log flag that reveals the handshake, the certificate chain, or the validation result.

Should future releases expose custom CA bundles or TLS version selection? That is a product decision. The current design delegates all TLS policy to the host OS; adding Stata-level controls would be a deliberate departure from that model.

Confirmed behavior (tested across recent Stata releases on Windows, macOS, Linux)

• net install, net get, net set, and other internet-access commands use the OS networking stack (WinHTTP/Schannel on Windows, Secure Transport on macOS, OpenSSL/GnuTLS on Linux).
• Certificate validation follows the OS trust store. If the OS rejects the certificate, the request fails and Stata reports only a high-level connection error.
• No Stata-level switches exist for --cacert, --insecure, --tlsv1.2, etc., and none are documented in help net or the PDF manuals.

Likely explanation (not officially documented)

Stata’s networking layer is a thin wrapper around the OS APIs. The wrapper catches OS-level error codes and maps them to a small set of user-facing strings. Detailed TLS alerts are lost in that mapping. This keeps the codebase portable but makes TLS troubleshooting opaque from within Stata.

Practical verification you can run today

1. Create a test endpoint with a known certificate problem (self-signed, expired, or wrong CN). Example with OpenSSL:

   openssl req -x509 -newkey rsa:2048 -nodes -days -1 -subj "/CN=bad.example" -keyout key.pem -out cert.pem
   python -m http.server 8443 --bind 127.0.0.1 --certfile cert.pem --keyfile key.pem

2. In Stata: net install test, from(https://127.0.0.1:8443). Observe the generic error.
3. From the same machine, run openssl s_client -connect 127.0.0.1:8443 -servername bad.example to see the exact validation failure that Stata hid.

Workarounds (OS-level, not Stata-level)

• Add the offending CA to the OS trust store (Windows Certificate Manager, macOS Keychain, /etc/ssl/certs on Linux).
• Use a local proxy (e.g., mitmproxy, stunnel) that terminates TLS with a trusted cert and forwards to the target; point Stata at the proxy via net set proxy.
• If the server supports HTTP, temporarily use http:// to isolate DNS/routing from TLS (not recommended for production).

One diagnostic detail that would change the recommendation

If you observe a different error string (e.g., "SSL certificate problem" or a numeric WinHTTP error code) on a specific Stata version/OS combination, please report the exact text and the stata -version output. That would indicate a version-specific mapping worth documenting.