SysAdmin

Explains how to access AWS EC2 user data from within an instance using the instance metadata service. Covers the metadata endpoint, a curl example, and where the user data script is stored on Linux and Windows.

Learn how to insert iptables rules at a specific position using the -I flag, with syntax breakdown and a practical SSH example.

A practical cheat sheet for managing firewalld on RHEL, Fedora, and CentOS systems. Covers zones, services, ports, rich rules, NAT, and direct iptables-style rules.

A guide to building a Kubernetes cluster manually, component by component, without kubeadm or minikube. This approach provides a deep understanding of how Kubernetes works under the hood and prepares you for both certification exams and day-to-day operations.

Catalogs the active Flannel CNI configuration and the full set of 19 available CNI plugin binaries on a Kubernetes node. Provides file sizes, modification dates, and the purpose of each installed plugin.

Clarifies which CNI plugins are acceptable for the CKA exam and explains why the official Kubernetes documentation avoids vendor-specific deployment commands.