Troubleshooting

Learn how to extract dynamic symbols from the mysqld binary and use them to resolve a crash stack dump into readable function names.

Exim offers two DKIM-related toggles that work together to validate and enforce sender signatures. Setting both to On ensures your mail server actually checks incoming DKIM records and rejects messages that fail validation.

A quick reference for enabling verbose output when sending mail from the command line, so you can see the full SMTP transaction and diagnose delivery issues.

A quick three-command recipe for grabbing a full thread backtrace from a running httpd process with gdb, useful when Apache appears hung or unresponsive.

A quick bash one-liner to pull offending IP addresses from exim relay-denied entries and resolve them to hostnames, making it easier to identify which gateways are misconfigured.

A practical, step-by-step guide for diagnosing and recovering from common InnoDB corruption issues, covering first response, log analysis, checksum verification, and data restoration techniques.