https://ranjithr.com Linux System Administrator specializing in AWS Cloud, DevOps Automation, Infrastructure Security, Resume Lab and DevOps Toolkit. en-us Sun, 26 Jul 2026 01:02:34 GMT https://ranjithr.com/learn/linux/file-permissions-ownership-umask https://ranjithr.com/learn/linux/file-permissions-ownership-umask Wed, 01 Jul 2026 00:00:00 GMT The rwx permission model, chmod symbolic vs. octal notation, chown/chgrp, setuid/setgid/sticky bits, and how umask sets your defaults. Linux https://ranjithr.com/learn/linux/cron-systemd-timers https://ranjithr.com/learn/linux/cron-systemd-timers Wed, 01 Jul 2026 00:00:00 GMT Crontab syntax, special strings, run-parts directories, and modern systemd timer units — with a direct comparison of when to use each. Linux https://ranjithr.com/learn/linux/ssh-hardening https://ranjithr.com/learn/linux/ssh-hardening Wed, 01 Jul 2026 00:00:00 GMT Disabling password auth, key-based login, sshd_config hardening, fail2ban jails, and bastion-host architecture for production access. Linux https://ranjithr.com/learn/linux/lvm-from-scratch https://ranjithr.com/learn/linux/lvm-from-scratch Wed, 01 Jul 2026 00:00:00 GMT Physical volumes, volume groups, and logical volumes — creating, extending, and shrinking storage without unmounting production filesystems. Linux https://ranjithr.com/learn/aws/iam-fundamentals https://ranjithr.com/learn/aws/iam-fundamentals Wed, 01 Jul 2026 00:00:00 GMT Users vs. roles vs. groups, identity-based vs. resource-based policies, policy evaluation logic, and applying least privilege in practice. 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AWS https://ranjithr.com/learn/devops/git-branching-strategies https://ranjithr.com/learn/devops/git-branching-strategies Wed, 01 Jul 2026 00:00:00 GMT Git Flow's branch model compared against trunk-based development with short-lived feature branches and feature flags — with a decision framework. DevOps https://ranjithr.com/learn/devops/docker-compose-multi-container-apps https://ranjithr.com/learn/devops/docker-compose-multi-container-apps Wed, 01 Jul 2026 00:00:00 GMT compose.yaml services, networks, volumes, environment files, healthchecks, and dependency ordering for a real app + database + cache stack. DevOps https://ranjithr.com/learn/devops/kubernetes-pods-deployments-services https://ranjithr.com/learn/devops/kubernetes-pods-deployments-services Wed, 01 Jul 2026 00:00:00 GMT The Pod as the atomic unit, Deployments for replica management and rollouts, and Services (ClusterIP/NodePort/LoadBalancer) for stable networking. 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Resume Lab https://ranjithr.com/blog/wazuh https://ranjithr.com/blog/wazuh Sat, 18 Apr 2026 00:00:00 GMT Wazuh manager/indexer/dashboard architecture, agent deployment, custom detection rules, alert tuning, and the operational dashboard workflow. Wazuh https://ranjithr.com/blog/owasp https://ranjithr.com/blog/owasp Thu, 02 Apr 2026 00:00:00 GMT SQL injection, XSS, CSRF, RCE, and the rest of the OWASP Top 10 — with vulnerable/fixed code examples and the security headers that stop them. OWASP https://ranjithr.com/blog/bitbucket https://ranjithr.com/blog/bitbucket Sun, 22 Mar 2026 00:00:00 GMT Repository setup, Bitbucket Pipelines YAML, branching permissions, pull requests, and deployment stages to servers and cloud targets. Bitbucket https://ranjithr.com/blog/nagios https://ranjithr.com/blog/nagios Sun, 15 Mar 2026 00:00:00 GMT Nagios Core installation, NRPE agent setup, host and service checks, notification/escalation rules, and the commands you'll run daily. Nagios https://ranjithr.com/blog/ansible https://ranjithr.com/blog/ansible Tue, 10 Mar 2026 00:00:00 GMT Inventory files, playbooks, variables, roles, handlers, Ansible Vault, and real-world playbooks for hardening and deploying servers at scale. Ansible https://ranjithr.com/blog/jenkins https://ranjithr.com/blog/jenkins Sun, 01 Mar 2026 00:00:00 GMT Installation, declarative pipelines, agents, credentials, GitHub/Bitbucket webhooks, deployment stages, and pipeline troubleshooting. Jenkins https://ranjithr.com/blog/sonarqube https://ranjithr.com/blog/sonarqube Wed, 25 Feb 2026 00:00:00 GMT Installation, quality profiles, quality gates, scanner configuration for multiple languages, and wiring SonarQube into a CI/CD pipeline. SonarQube https://ranjithr.com/blog/aws https://ranjithr.com/blog/aws Sat, 14 Feb 2026 00:00:00 GMT IAM, EC2, S3, Route53, CloudFront, ACM, RDS, CloudWatch, VPC, ALB, and Security Groups — with real deployment architectures and interview questions. AWS https://ranjithr.com/blog/docker https://ranjithr.com/blog/docker Mon, 02 Feb 2026 00:00:00 GMT Containers, images, volumes, networks, Dockerfiles, Compose stacks, private registries, and the troubleshooting playbook for production containers. Docker https://ranjithr.com/blog/cloudflare https://ranjithr.com/blog/cloudflare Wed, 28 Jan 2026 00:00:00 GMT DNS management, SSL/TLS modes, caching rules, firewall, WAF, rate limiting, page rules, origin certificates, and Cloudflare Tunnel. Cloudflare https://ranjithr.com/blog/git https://ranjithr.com/blog/git Tue, 20 Jan 2026 00:00:00 GMT Git internals, branching, merging, rebasing, cherry-picking, stashing, resetting, reverting, tagging, Git Flow, and resolving merge conflicts for real. Git https://ranjithr.com/blog/linux https://ranjithr.com/blog/linux Mon, 12 Jan 2026 00:00:00 GMT Filesystem hierarchy, permissions, users & groups, systemd, journald, cron, networking, SSH hardening, disk management, LVM, and RHCSA exam tips. Linux https://ranjithr.com/blog/cpanel https://ranjithr.com/blog/cpanel Mon, 05 Jan 2026 00:00:00 GMT Account management, email configuration, backups, SSL, DNS zones, PHP versions, and MySQL administration through cPanel/WHM. cPanel