Linux & DevOps Troubleshooting Blog
Practical guides for Linux engineers — NGINX debugging, process troubleshooting, CIS hardening, and production incident response.
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79 posts · page 2 of 9
SSH Connection Refused Linux: Fix Guide
Fix SSH connection refused on Linux — diagnose why SSH won't connect, check sshd service and firewall, recover from lockout, and harden SSH without breaking access.
How to Search Text in Files Linux: grep Examples
Search text in files in Linux with grep — recursive search, regex patterns, context lines, count matches, and real-world log investigation examples.
How to Restart Network Service in Linux (All Distros)
Restart network service in Linux using systemctl, nmcli, and ip commands — covering Ubuntu, RHEL, Debian, and CentOS with real examples and what to do when restart fails.
Port Already in Use Linux: How to Find and Fix It
Fix 'port already in use' errors on Linux — find what process owns the port, kill it safely, handle TIME-WAIT sockets, and prevent the issue from recurring.
ping vs curl vs telnet: Which to Use for Network Testing
Know when to use ping, curl, and telnet for network testing — what each tool tests, what its limitations are, and which to reach for first when debugging connectivity issues.
Permission Denied Linux: Fix with chmod and chown
Fix 'permission denied' errors in Linux — read permission bits correctly, use chmod and chown safely, debug with ls -la and stat, and avoid common mistakes that break applications.
Nginx Rate Limiting Configuration: Practical Guide With Examples
Configure nginx rate limiting with limit_req_zone and limit_req — with real examples for API protection, login endpoints, and burst handling in production.
Nginx 502 Bad Gateway Fix: Root Causes and Solutions
Fix nginx 502 bad gateway errors — identify the root cause from the error log, fix upstream connection issues, keepalive config, and timeout problems in production.
netstat vs ss: Which to Use and What's the Difference
netstat vs ss — understand the differences, when to use each, equivalent command translations, and why ss is the modern replacement for netstat on Linux.