AirMac Extreme doesn't have built-in VPN server functionality

AirMac Extreme lacks a built-in VPN server, so use VPN passthrough with a LAN-side VPN server instead.

Configuration Method for Setting Up Two AirMac Extreme Units

Extending Wi-Fi with two AirMac Extreme units: factory reset, Google Public DNS, and reference links.

Hosting a static website on Amazon S3

Hosting a static site on Amazon S3, both S3-only and in combination with CloudFront.

Amazon WorkSpaces Personal on Simple AD at small scale — setup, cost, and scaling paths

I set up a single-purpose Windows desktop on Amazon WorkSpaces Personal with Simple AD, for a small team that needs a browser and client certificates for a specific line of business. As of July 30, 2026, Simple AD is closed to new customers, and existing customers keep full functionality. This post covers the minimum setup, Tokyo-region monthly costs, what Simple AD gets you and where it falls short, the trade-offs of AWS Managed Microsoft AD and AD Connector, and the limits of WorkSpaces backup and restore, with citations to AWS official documentation.

Restricting AWS ALB Access to CloudFront Only

Reference articles for restricting AWS ALB access to CloudFront-only traffic, with HTTPS pattern notes.

Comparison Information for AWS Batch and Job Services - AWS Batch, Lambda, ECS Task

Reference articles and decision notes for choosing between AWS Batch, Lambda, and ECS Task for batch jobs.

Why I Gave Up on AWS Copilot CLI for Preview Environments

I ran a PoC to build preview environments with AWS Copilot CLI and ended up abandoning the approach. Here's what went wrong and what I learned.

[AWS EC2] Instance Store - Ephemeral Disk (volatile disk) can be used for free

AWS EC2 instance store (Ephemeral Disk) is free to use, with the caveat that data is wiped on instance stop.

About AWS EC2 instance-specific network bandwidth and bandwidth guarantee

Measured per-instance EC2 network bandwidth references and confirmation that AWS does not guarantee it.

AWS EC2 instance selection meeting Wowza Streaming Engine minimum recommended specifications

Choosing AWS EC2 instance types that meet Wowza Streaming Engine's minimum recommended specifications.

[AWS] Moving from Private Subnet to Public Subnet to Reduce NAT Gateway Costs

How I reduced NAT Gateway costs by moving ECS Scheduled Tasks from a private subnet to a public subnet.

HTTPS Support with AWS S3 + CloudFront + Route53

Serving an S3 static site over HTTPS by adding CloudFront in front of an S3 + Route53 setup.

Cost Comparison Between Amazon S3 Standalone and S3 + CloudFront Configuration

Comparing costs and trade-offs between S3 standalone and S3 + CloudFront to decide which fits your workload.

How to Build a Proxy Server with Squid3

Steps for building an HTTP proxy server on Ubuntu using Squid 3.x.

[Cacti] Monitoring Target Addition Procedure Memo

A quick memo on adding a new monitoring host to Cacti and placing it in a Graph Tree.

I Cancelled My Sakura VPS

Notes on cancelling Sakura VPS and planning a migration to Sakura Cloud.

CDN Implementation Proposal

A CDN proposal covering the basics, trade-offs, and choosing between CloudFront and Fastly.

How to check CentOS support end-of-life dates

Where to look up the end-of-life date for each CentOS release.

How to publish a static website with custom domain using Amazon CloudFront + S3 + Route 53

Publishing a static site on a custom domain with CloudFront + S3 + Route 53, including OAI and HTTPS setup.

ConoHa VPS is Recommended for Server Cost Discounts Through Shareholder Benefits

How GMO Internet's shareholder benefit knocks 5,000 yen off ConoHa VPS server costs, plus pros and cons.

[Linux] Checking name servers with the dig command

Using `dig <domain> NS` to look up the name servers for a specific domain.

[DigitalOcean] Solution for 'You cannot create more than 10 droplets at a time' Error

Working around the 10-droplet batch limit when creating Droplets via the DigitalOcean API.

Collection of Articles That Help Understand DNS Propagation

A short link collection of articles that explain how DNS propagation works.

Solution for ECR Connection Error After Changing VPC Settings with S3 Endpoint on AWS

Notes on resolving ECR 403 Forbidden errors after VPC changes, focused on the S3 gateway endpoint that ECR relies on.

Feature Flag Service Comparison — How to Choose Between OSS, Self-Hosting, and Japan Region

A comparison of major feature flag services, from SaaS offerings like LaunchDarkly to OSS options such as Unleash, Flagsmith, GrowthBook, and Bucketeer. Also covers how to choose a self-hosting strategy with the Japan region in mind.

[Fluentd] The Origin of .pos File Name is Position

The Fluentd .pos file gets its name from 'position' — where the tail input last read to.

[Heroku] Runs on Amazon EC2 North America Region, Response Time from Japan is Around 300ms

A 2012 snapshot noting Heroku ran only on Amazon EC2 US East, with roughly 300 ms response times observed from Japan.

[Heroku] Action Required: Legacy Routing End of Life

Reacting to Heroku's legacy routing end-of-life notice by planning a CloudFlare CNAME flattening setup for the naked domain.

Solution for large /tmp/magick-xxx files created by ImageMagick and policy.xml configuration changes

Cleaning up massive /tmp/magick-xxx files and tuning ImageMagick's policy.xml resource limits.

Steps to Install Latest Stable Nginx on Ubuntu LTS 16.04

Add the official Nginx apt repository to Ubuntu 16.04 and install the latest stable 1.12.0.

Solution for No space left on device error ~ inode depletion edition

Tracking down a No space left on device error on Linux to inode depletion caused by wp-file-cache.

[iptables] Applying firewall rules: iptables-restore v1.4.7: no command specified Error occurred at line: 6

The `no command specified` error on iptables restart was caused by whitespace on a blank line.

How to Quickly Build a Japanese IP VPN with OpenVPN + Linode

Quickly build a Japan-IP VPN with Linode's Tokyo 2 region and the OpenVPN Marketplace one-click app.

Librato Metrics - Service for Metrics, Monitoring, and Alerts

A bookmark note on Librato Metrics, a SaaS for metrics, monitoring, and alerts.

[Linode] How to find Coupon Code and Referral Code

Finding Linode coupon codes and using a referral code at signup.

Creating Infrastructure Diagrams with Miro

Where to grab AWS, GCP, and Azure icon assets for infrastructure diagrams in Miro.

[Nagios] Changing check_load Settings for Load Average Monitoring

Tightening Nagios's check_load intervals so load average spikes get flagged sooner.

[Nagios] Configuration File Verification, Reloading, etc.

Nagios commands for validating configuration files and reloading them without a full restart.

Collection of Articles Useful for Nagios Introduction and Configuration

A curated reading list for getting started with Nagios and configuring it in practice.

net-snmp Installation and Configuration Method

Installing net-snmp with yum and configuring snmpd.conf, service startup, and iptables port rules for Nagios monitoring.

Netlify becomes faster depending on root domain and subdomain assignment

Which combination of Netlify DNS or subdomain assignment lets Geo-targeting kick in and make sites faster.

Investigating Netlify Server Location and Region

Using nslookup, traceroute, and ip2location to identify a Netlify site's server location as Singapore.

Personal Study Methods and How-To Guide for Network Technology

A self-study guide to networking for app engineers — books, hands-on tips, a troubleshooting checklist, and must-have gear.

[Nginx] add_header Not Reflected Due to Overwrite Issue and Solution

Why Nginx add_header at the server level disappears when a location block adds one, and how to work around it.

[Nginx] How to Check Compile Options

Use nginx -V to inspect the configure arguments and enabled modules of an installed Nginx binary.

[Nginx] Access restriction configuration to block specific IP addresses

Adding a deny directive inside a location block to block a specific IP address in Nginx.

[Nginx] How to Exclude Specific URLs from Basic Authentication

Using satisfy any and allow all to exempt specific URLs or static assets from Nginx Basic auth.

[Nginx] Configuration to Redirect HTTP to HTTPS & HTTP Strict Transport Security (HSTS) Support

Nginx configs for a 301 HTTP→HTTPS redirect and the HSTS header, plus how to submit to the HSTS Preload List.

[Nginx] upstream timed out (110: Connection timed out) while reading response header from upstream

How I resolved Nginx 504 Gateway Time-out errors by switching PHP-FPM's pm to static and retuning it.

[Nginx] How to Configure Redirects from www URLs to Non-www URLs

How to set up a 301 redirect from www URLs to non-www URLs in Nginx using rewrite.

How to Remove WordPress Cache Plugin WP File Cache

How I deactivated and completely removed the WP File Cache plugin after it exhausted the server's inodes.

On-Premise vs Cloud Decision Criteria

Decision criteria between on-premise and cloud from a cost perspective, with Dropbox's AWS repatriation as a case study.

[PHP-FPM] WARNING: [pool www] server reached pm.max_children setting (30), consider raising it

Fixing PHP-FPM's pm.max_children WARNING and Bad Gateway by raising the setting in www.conf.

[PHP-FPM] recv() failed (104: Connection reset by peer)

Raising PHP-FPM's request_terminate_timeout to 120s to stop frequent 502 Bad Gateway errors.

[PostgreSQL] Configuration for Connecting from Other PCs

Configuring `listen_addresses` and pg_hba.conf so PostgreSQL accepts connections from other hosts.

How to Install Python 2.7.1 on CORESERVER

Installing Python 2.7.1 on CORESERVER and fixing python -V still showing 2.4.3.

'Kubernetes Complete Guide 2nd Edition' is a Recommended k8s Beginner Book

A quick recommendation of 'Kubernetes Complete Guide 2nd Edition' as a good first book for Kubernetes.

Reading Notes: 'Infrastructure Design Theory - From Requirements Definition to Operations and Maintenance'

Reading notes on 'Infrastructure Design Theory', covering non-functional requirements grades, availability, and ops design.

Redis Replication (Master-Slave) Environment Setup [docker-compose Edition]

Setting up and verifying a Redis master-slave replication environment with docker-compose.

Deciding Whether to Enable or Disable Redis TLS Support

Two perspectives — zero trust vs. safe-within-VPC — for deciding whether to enable Redis TLS.

Lesson learned: Check router's DHCP allocation limit when you get 'Cannot connect to internet due to self-assigned IP address' error

The lesson: when Wi-Fi hits a self-assigned IP error, check the router's DHCP allocation limit — mine was capped at 32.

[Ruby] God : The server is not available (or you do not have permissions to access it)

How I resolved god's 'The server is not available' error by loading the config file with an explicit path instead of a glob.

[Ruby] Uninstalling Passenger

Example console output for uninstalling the Phusion Passenger gem with `gem uninstall passenger`.

Received a ¥20,000 Free Coupon for 'Sakura Cloud'

Got a 20,000 yen Sakura Cloud coupon and started planning a migration from Sakura VPS.

Reference links for creating a server on Sakura Cloud

Official Sakura Cloud manual links used from account creation through server setup.

For Sakura Cloud and VPS CPU specifications, you have to check cpuinfo yourself

Sakura support won't share physical host CPU specs — you have to check /proc/cpuinfo yourself.

[Server] Initial Setup of CentOS 6.3 on Sakura VPS

Initial setup for Sakura VPS's CentOS 6.3 — admin user, SSH, iptables, and yum.

Story of registering for Sakura VPS's 2-week free trial period to set up with Ansible

Signed up for Sakura VPS's 2-week free trial to prepare for Ansible-based server setup.

I Was Thinking 'There's an UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY Error!' When I Received an Email Titled '[Sakura VPS] Report on Failure'

A Sakura VPS host hardware failure caused fsck errors — I opted to restore from their backup.

[Sakura VPS] Installing Ubuntu 12.04

Installed Ubuntu 12.04 on Sakura VPS by following the official custom OS installation guide.

Shopify's Infrastructure is Google Cloud Platform (GCP)

A quick note that Shopify runs its infrastructure on Google Cloud Platform, sourced from Shopify's engineering blog.

Summary of Helpful Articles When Getting Started with SNMP

A link roundup of ITmedia and CodeZine articles I used to get started with SNMP.

Stopped MAC Address Filtering Function

Why I turned off office Wi-Fi MAC address filtering after finding the security benefit didn't justify the maintenance cost.

[Network] Subnet Mask Reference Table

A quick lookup table of subnet masks — IP counts, dotted mask values, and prefix lengths.

[Tomcat] How to Change Port Number Configuration

Change Tomcat's port from 8080 to 80 by editing the Connector in tomcat/conf/server.xml.

Beyond Trivy and tfsec - Comparing Alternative Security Scanning Tools (Grype, Checkov, Snyk, KICS)

The Trivy supply chain compromise and tfsec's maintenance-mode status have made it urgent to evaluate alternative security scanning tools. This article compares options beyond Trivy and tfsec: Grype, Snyk, and Docker Scout for vulnerability scanning, and Checkov and KICS for IaC scanning, with practical guidance on selection criteria and recommended combinations.

Understanding Load Average

Notes on reference articles for understanding load average on multi-core Linux systems.

Upgrading Nginx Version with yum ~ CentOS 6

Steps to upgrade Nginx to a newer version with yum on CentOS 6.

VALUE-DOMAIN DNS Settings Not Reflecting Due to Unconfigured Name Servers

How to fix VALUE-DOMAIN DNS not reflecting by configuring the name servers to ns*.value-domain.com.

[YAMAHA RTX1210] How to Configure DHCP Reserved Addresses

Configuring a DHCP reserved address on the YAMAHA RTX1210 VPN router, with the commands I ran from the maintenance console.

YAMAHA WLX302 Configuration

Notes on the YAMAHA WLX302 wireless AP — max client counts, link-speed channel profiles, and SSID operation plans.