Measure DNS Server Performance

January 10, 2022

Originally published January 10, 2019 @ 6:35 pmThis is not an entirely proper way to benchmark a DNS server, but, in a pinch, it should give you some idea of its responsiveness and stability. The commands below require dig (provided by the bind-utils package), and shuf (provided by the coreutils…Read More

The Facebook Fracas

December 22, 2021

Originally published December 20, 2018 @ 10:31 pmThe Facebook privacy saga is getting ridiculous. You’re using a free service that you signed up for – nobody was holding a gun to your giant head. And it’s not Gulag either: just delete your profile, uninstall the damned app, and forget Facebook…Read More

Killing Process Network Access

December 21, 2021

Originally published December 19, 2018 @ 6:32 pmImagine this scenario: a particular process on your server is connecting to a host outside your internal network and you don’t like that. On the other hand, you can’t just kill that process because you need it. The simple script below uses tcpkill…Read More

Generating and Running Multiple Scripts

December 20, 2021

Originally published December 19, 2018 @ 5:41 pmAdmittedly, this has a limited range of practical applications and is more of a scripting exercise. The command shown here generates a bunch of temporary scripts each containing the sleep command for up to one minute. The scripts are ran in the background…Read More

Removing Chef Server Installation

December 19, 2021

Originally published December 19, 2018 @ 11:41 amJust a quick note on how to completely remove (more or less) Chef server installation from a CentOS/RHEL box. There are a bunch of bits and pieces all over the place and it took me a few minutes to figure this out, so…Read More

Installing t CLI power tool for Twitter

December 15, 2021

Originally published December 15, 2018 @ 9:14 pmThe ‘t’ is an excellent Ruby-based CLI utility for interacting with the Twitter API written by Erik Berlin. This is certainly not the only such tool available, but, in my estimation, it is the most full-featured and expertly-written. No amateur-hour coding here. Here…Read More

Keeping Abreast with Filesystem Changes

December 13, 2021

Originally published December 13, 2018 @ 11:48 am The inotify is a Linux kernel sybsystem for notifying user-space applications of filesystem changes. I always thought this exceptionally handy utility was under-appreciated or at least underutilized. I am not planning on going through the many features of inotify, but instead will…Read More

Resizing Photos for Instagram

December 12, 2021

Instagram is being a pain in the neck by limiting support to specific aspect ratios. Currently, you can only upload photos of no less than a 4/5 ratio for portrait mode and the peculiar 16/8.377 ratio for landscape shots, which is just a smidgen over the standard 16/9. Neither ratio…Read More

Curated Downloads

November 21, 2021

Originally published November 20, 2018 @ 6:21 pm A curated list of useful or otherwise interesting (to me) downloads. These are all things I installed, configured and, at the very least, played with for a few days. I will add a lot more stuff to this list, time permitting. Please…Read More

Grouping Output of SSH via xargs

November 19, 2021

To make a long story short, I have a list of servers where I need to execute a command and get back the output. Using a for loop to run SSH with key authentication is the usual approach, except in this case accessing one server at a time was taking…Read More

Exporting WordPress to Markdown

November 14, 2021

WordPress is my favorite CMS, but the complexity and security issues introduced by PHP and the database are unnecessary in some cases. Migrating to a static Web site may be a better option when it is all you need. There are plenty of choices like Gatsby, Hugo, and Jekyll. The…Read More

QNAP NAS Performance Analysis

November 7, 2021

The QNAP Resource Monitor utility available via the Web UI provides a lot of useful functionality with good visual presentation. However, sometimes you need just a little bit more detail to help track down a particularly elusive performance issue. The purpose of this quick write-up is to help you install…Read More

Auto-Update /etc/hosts

October 29, 2021

Originally published October 29, 2018 @ 1:05 pm This was a silly solution to a silly problem, but may come in handy in the future for other things. A user process was establishing frequent connections to a handful of FQDNs. Not having any IP caching capability, every connection attempt was…Read More

Find Large Folders

October 22, 2021

Originally published October 21, 2018 @ 6:19 pm When you get a filesystem space alert (and they tend to arrive at 3:37 on Saturday morning), deleting various supersized log files is one option I already covered in adequate detail. That is if you get so lucky as to find such…Read More

Laziness vs Phishing

October 14, 2021

Here’s an interesting article 1 detailing the methods scammers use to steal your one-time passwords for Coinbase. People criticize Coinbase for not doing more to fend off the phishing bots. Well, it’s not as easy as it sounds and expensive. The bottom line is: fighting the bots won’t reduce the…Read More

Awk & sed Snippets for SysAdmins

October 7, 2021

Books have been written on the subject of awk and sed. Here’s a small sample of commands I put together over the years that are useful for everyday system administration tasks. Most of these tasks involve reformatting strings and files, which is why I decided to bundle tr, cut, and…Read More

Synology NAS Hacks

October 6, 2021

I’ve been using various Synology NAS devices for many years now, and they’re great. Well, almost. There are a few rough spots that don’t thrill me. These consumer-grade devices are designed to be difficult to break by people who know little about computers. This approach also annoys the living daylights…Read More

Finding Duplicate Photos

September 25, 2021

Being a shutterbug and a digital hoarder can get expensive. A couple of days ago, my TerraMaster D5-300 5-bay DAS crashed. Again. This time it was the power supply. I replaced it only to discover that my RAID 5 volume is toast. It was still rebuilding the failed drive I…Read More

Inventory Network Services with Nmap

September 23, 2021

Originally published September 23, 2018 @ 2:01 pm With the growing number of network-enabled devices in your home, meaningful security becomes elusive. The first step to addressing the situation is knowing what you have. A few examples below use the nmap utility to scan your local network and detect active…Read More

Maryland Renaissance Festival

September 17, 2021

Originally published September 17, 2018 @ 11:38 pm The second largest fairy of its kind in the US has been operating in Crownsville, MD, sine 1977. The event is centered around a permanent Tudor-style village and is open in September and October. Every year the theme of the festival is…Read More

Collatz Conjecture in Bash

September 17, 2021

The Collatz conjecture is a math problem from the mid-1930s. It involves an algorithm that starts with any positive integer, and then each following number is made by taking the previous number and changing it. If the number n is even, you make it half of what it was (n/2).…Read More

Simple Math from Bash Command Line

September 13, 2021

Chances are, most shell scripts you write will require some math operations, even if it’s something as simple as incrementing a variable inside of a loop. As with everything else in Linux, there are multiple ways of accomplishing the same task. Here’s a quick look at some of the options.…Read More

Focus Stacking with Lightroom and Photoshop

September 6, 2021

Not the usual topic for this blog and not the most comprehensive guide on the subject out there, but here I go anyway. Focus stacking combines multiple photos taken at different focal distances into an image of greater depth of field. Focus stacking is used primarily in close-up photography: macrophotography…Read More

Generating Honeypot Data Structure

September 4, 2021

I’ve been fiddling with my inotifywatch scripts to make a better “early-warning” system for ransomware detection and realized I needed a more realistic honeypot data structure. Ransomware is getting more clever and is no longer easily fooled by dummy files from /dev/urandom or popular file collections. This all started early…Read More

Peculiar Linux Command-Line Tools

September 1, 2021

Some Linux CLI commands I type every day, probably hundreds of times. Others – on a rare occasion. But there’s a category of truly esoteric utilities tailor-made for some singular and often exotic purpose. I heard of many – if not most – of these utilities, but it’s difficult to…Read More