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Raymond Ops

Linux ops automation, cloud-native, Kubernetes, SRE, DevOps, Python, Golang and related tech discussions.

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Latest from Raymond Ops

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Raymond Ops

Aug 15, 2026 · Information Security

Frequent SSH Brute‑Force Attacks? Essential Defense Measures You Must Configure

When a server is exposed to the Internet, SSH brute‑force attempts are inevitable; this guide walks Linux operators through log analysis, disabling password authentication, enabling public‑key and 2FA, configuring fail2ban, changing the default port, restricting source IPs, deploying OSSEC, and automating daily and weekly security checks.

Fail2banLinux securitySSH

0 likes · 30 min read

Frequent SSH Brute‑Force Attacks? Essential Defense Measures You Must Configure

Raymond Ops

Aug 14, 2026 · Operations

Why Do Docker Containers Fail to Start? Common Causes and Troubleshooting Commands

This guide walks operators through the most frequent reasons Docker containers fail to start—such as image issues, misconfigurations, resource limits, permission problems, network errors, and volume mishaps—and provides a step‑by‑step command checklist to diagnose and fix each scenario.

DockerResource LimitsTroubleshooting

0 likes · 28 min read

Why Do Docker Containers Fail to Start? Common Causes and Troubleshooting Commands

Raymond Ops

Aug 14, 2026 · Operations

How to Diagnose and Fix 502, 504, and Connection Reset Errors in Nginx

This guide explains the distinct causes of 502 Bad Gateway, 504 Gateway Timeout, and Connection Reset errors in Nginx reverse‑proxy setups and provides a step‑by‑step, four‑segment troubleshooting workflow with concrete log examples, shell commands, and configuration recommendations.

502 Bad Gateway504 Gateway TimeoutConnection Reset

0 likes · 24 min read

How to Diagnose and Fix 502, 504, and Connection Reset Errors in Nginx

Raymond Ops

Aug 13, 2026 · Operations

How to Implement Nginx Rate Limiting: Protect Against Brute‑Force, Crawlers, and Traffic Spikes

This article explains how to use Nginx's built‑in limit_req and limit_conn modules—based on the leaky‑bucket algorithm—to throttle requests by IP or API key, configure burst and nodelay behavior, apply whitelists, customize error responses, fine‑tune with delay and dry‑run modes, and monitor effectiveness in production environments.

API securityNginxRate Limiting

0 likes · 22 min read

How to Implement Nginx Rate Limiting: Protect Against Brute‑Force, Crawlers, and Traffic Spikes

Raymond Ops

Aug 12, 2026 · Operations

Avoid These 10 Common Docker Pitfalls in Production

This article enumerates the ten most frequent Docker problems encountered in production—such as disk exhaustion, time drift, DNS failures, OOM kills, network issues, data loss, tag confusion, PID‑1 signal handling, missing resource limits, and exposed daemon ports—detailing their symptoms, underlying causes, diagnostic commands, remediation steps, and preventive measures, plus five additional hidden traps.

DevOpsDockerProduction

0 likes · 34 min read

Avoid These 10 Common Docker Pitfalls in Production

Raymond Ops

Aug 12, 2026 · Information Security

Common Security Configuration Issues Ops Face During GB/T 22239-2019 (Level‑2/3) Compliance

This guide walks operations engineers through the background, requirements, typical audit findings, step‑by‑step remediation commands, and verification methods for the most frequent security configuration problems encountered when implementing GB/T 22239‑2019 Level‑2/3 compliance on CentOS 7/8 and Ubuntu 20.04, covering identity authentication, access control, auditing, intrusion prevention, resource limits, and data confidentiality.

GB/T 22239Linux securityResource Limits

0 likes · 23 min read

Common Security Configuration Issues Ops Face During GB/T 22239-2019 (Level‑2/3) Compliance

Raymond Ops

Aug 11, 2026 · Databases

How to Diagnose MySQL Slow Queries: From Log Capture to Index Optimization

This guide walks MySQL operators through a complete slow‑query troubleshooting workflow—starting with enabling and analyzing the slow‑query log, using pt‑query‑digest and EXPLAIN to pinpoint index, SQL, schema, configuration or hardware bottlenecks, and then applying concrete optimizations such as proper indexing, cursor pagination, JOIN tuning, and server‑level parameter tweaks.

EXPLAINJOIN tuningMySQL

0 likes · 33 min read

How to Diagnose MySQL Slow Queries: From Log Capture to Index Optimization

Raymond Ops

Aug 11, 2026 · Operations

How to Quickly Identify High‑CPU Processes on a Linux Server with a One‑Minute Command Checklist

This article walks through a systematic, three‑stage method—starting with a 60‑second global scan using uptime, top, vmstat and mpstat, then pinpointing the offending process and thread with pidstat, perf and strace, and finally classifying the root cause to apply the appropriate fix—so you can diagnose and resolve Linux CPU spikes without resorting to blind restarts.

CPULinuxTroubleshooting

0 likes · 16 min read

How to Quickly Identify High‑CPU Processes on a Linux Server with a One‑Minute Command Checklist

Raymond Ops

Aug 9, 2026 · Operations

How a Full Redis Connection Pool Triggered a Service Outage: Step‑by‑Step Investigation

An online education platform experienced a cascade failure when Redis reached its maxclients limit, causing authentication, session, and cache services to become unavailable; the article details the connection mechanism, root‑cause analysis, rapid mitigation steps, and long‑term best practices for preventing similar outages.

Circuit BreakerJedisRedis

0 likes · 18 min read

How a Full Redis Connection Pool Triggered a Service Outage: Step‑by‑Step Investigation

Raymond Ops

Aug 9, 2026 · Operations

Disk Full on Linux? Run These 8 Diagnostic Commands First

When a Linux server reports a full disk, the article explains three possible causes—actual space exhaustion, inode depletion, or deleted files still held by processes—and walks through eight essential commands, from df and du to lsof, ncdu, iostat, and journalctl, to diagnose and safely resolve the issue.

LinuxSystem AdministrationTroubleshooting

0 likes · 21 min read

Disk Full on Linux? Run These 8 Diagnostic Commands First