The .NET Framework 4.8 does not have a direct built-in equivalent to Java's -Djavax.net.debug=ssl:handshake for enabling SSL/TLS handshake debugging from the command line or via a simple configuration switch. However, you can achieve similar diagnostic output using the following approaches:
1. Enable System.Net Tracing (Recommended for .NET Framework)
You can configure System.Net tracing via your application's app.config or web.config file to log detailed information about network activity, including SSL/TLS handshakes.
Example app.config:
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This logs System.Net and System.Net.Sockets activity to a file (network.log).
While it doesn’t dump raw TLS handshake bytes like Java, it does show certificate validation, cipher suites negotiation (indirectly), and connection errors.
For more TLS-specific diagnostics, combine this with Windows-level tools (see below).
⚠️ Note: Tracing impacts performance—use only for debugging.
2. Use Windows Schannel Logging (OS-Level SSL Debugging)
.NET Framework uses the Windows Schannel (Secure Channel) security package for TLS. You can enable Schannel event logging via the Windows Event Log:
Open Event Viewer → Applications and Services Logs → Microsoft → Windows → Schannel.
Right-click Operational → Enable Log.
Reproduce your SSL issue; handshake errors and details will appear here.
