SysAdmin

Learn how to turn off ModSecurity for a specific domain or path using a single directive in your .htaccess file. This is useful when a legitimate request is being blocked by the WAF rules.

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 DNS amplification attack floods a victim with forged responses by exploiting open resolvers. This post walks through iptables rules and BIND hardening steps to block the attack vector.

A practical walkthrough of how DNS resolution works, from the hierarchical name space down to the iterative query process. Includes common zone file syntax mistakes and how to avoid them.

A quick one-liner to flush every message out of the Exim mail queue. Useful when a misconfigured relay or a flood of bounce messages has clogged up your server.

Learn how to manually decompress an RPM package into a working directory using rpm2cpio and cpio, without installing the package.