# Debugging SSL on Linux To help anyone looking at the SSL code, here are a few tips I've found handy. [TOC] ## Logging There are several flavors of logging you can turn on. * `SSLClientSocketImpl` can log its state transitions and function calls using `base/logging.cc`. To enable this, edit `net/socket/ssl_client_socket_impl.cc` and change `#if 1` to `#if 0`. See `base/logging.cc` for where the output goes (on Linux, usually stderr). * `HttpNetworkTransaction` and friends can log its state transitions using `base/trace_event.cc`. To enable this, arrange for your app to call `base::TraceLog::StartTracing()`. The output goes to a file named `trace...pid.log` in the same directory as the executable (e.g. `Hammer/trace_15323.log`). ## Network Traces http://wiki.wireshark.org/SSL describes how to decode SSL traffic. Chromium SSL unit tests that use `net/base/ssl_test_util.cc` to set up their servers always use port 9443 with `net/data/ssl/certificates/ok_cert.pem`, and port 9666 with `net/data/ssl/certificates/expired_cert.pem` This makes it easy to configure Wireshark to decode the traffic: do Edit / Preferences / Protocols / SSL, and in the "RSA Keys List" box, enter 127.0.0.1,9443,http,;127.0.0.1,9666,http, e.g. 127.0.0.1,9443,http,/home/dank/chromium/src/net/data/ssl/certificates/ok_cert.pem;127.0.0.1,9666,http,/home/dank/chromium/src/net/data/ssl/certificates/expired_cert.pem Then capture all tcp traffic on interface lo, and run your test.