Troubleshooting

A quick bash one-liner to identify which directories are consuming the most inodes on a Linux system, helping you pinpoint the source of ‘No space left on device’ errors when disk space still appears available.

A quick way to list every port a process is listening on, using lsof and a simple grep filter. Handy for troubleshooting connectivity issues or auditing what services are exposed on a host.

A troubleshooting walkthrough for getting mod_remoteip working correctly under Apache 2.4 and cPanel, including the right LogFormat directives and RemoteIP configuration so that access logs, mod_security, and other modules all see the real client IP.

A quick Apache mod_rewrite snippet that returns a 403 Forbidden to any request whose User-Agent matches a bot pattern. Drop it into your .htaccess and you are done.

A lightweight bash script that monitors Apache error logs for repeated access-denied entries and automatically blocks offending IPs via iptables. Useful for quick-and-dirty rate-based blocking without a full WAF.

A quick walkthrough of using mtr in report mode to capture packet loss data across network hops. Learn how to run a 30-cycle test and read the output to isolate where loss is occurring.