Practical Guides for Sysadmins: Linux, Windows, Networking & DevOps
Step-by-step tutorials, troubleshooting checklists and plain-English explainers for people who run servers, networks and desktops.
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Popular Troubleshooting Guides
- Fix “wmic is not recognized” on Windows 11
- Nginx 502 Bad Gateway: What It Really Means and How to Fix It
- MySQL/MariaDB Connection Refused: Checklist That Fixes It
- Cron Job Not Running? Checklist Before Blaming cron
- DNS Not Resolving on Linux: Checklist That Actually Works
- Cloudflare 522 on a Coolify VPS: How I Found the Real Cause
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Latest Posts
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New posts missing from your Rank Math sitemap? Here is the code path behind it in version 1.0.280, how to clear the stale cache, and a small must-use plugin workaround. - Coolify Dashboard Not Loading but Sites Are Up: Unhealthy Container After an Update
The Coolify dashboard stopped loading while the sites kept working. How to tell the proxy from the app, read the health check and log, and roll back a single container safely. - How to Safely Upgrade an Ubuntu VPS Running Docker (apt Checklist)
Upgrading 62 packages, including Docker and OpenSSH, on a VPS that hosts live sites: simulate first, run detached, expect a short SSH refusal, verify from outside, and plan the reboot. - Replace WP-Cron with a Real Cron Job (WordPress in Docker)
WP-Cron only runs when someone visits. The exact 5-minute host cron job I use for a WordPress container, the CLI memory error I hit, and how I verified it before disabling WP-Cron. - wp-config.php.bak Publicly Accessible? How to Check and Fix a Backup in the Web Root
A dated backup copy of wp-config.php in the web root was served over HTTPS. How I checked using only the status code, moved it, read the logs and what to rotate if secrets may have leaked. - Docker Bypasses UFW: Why Your Closed Port Is Still Open (and the Fix)
I deleted the UFW rule for a port and it still answered from the internet. Docker publishes ports before UFW sees the packets. How to check from outside and how to bind the port to localhost.
Hi, I’m Maruthi Vishnu
I’m a Systems Administrator and DevOps Engineer with 7+ years of hands-on IT experience. Started my career at Revalsys Technologies as a System Administrator — managing Windows Server, Active Directory and enterprise infrastructure. Then deepened my sysadmin expertise at vSplash Techlabs, before moving into DevOps and Cloud at Ratnam Solutions Private LTD where I work with AWS infrastructure today. sysadmin.co.in is where I document everything I learn, break, and build — so you don’t have to figure it out the hard way.
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