Inventory Network Services with Nmap

September 23, 2021

Originally published September 23, 2018 @ 2:01 pmWith 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 devices…Read More

Maryland Renaissance Festival

September 17, 2021

Originally published September 17, 2018 @ 11:38 pmThe 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 based…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

NFS I/O Stats with Logging

August 24, 2021

The nfsiostat is an excellent tool for analyzing NFS performance. The only major problem with this utility is that it’s designed to be used interactively. It does not have logging or timestamping capabilities. I needed to get information about NFS mount performance during a nightly backup, and I didn’t really…Read More

Inventorying NFS Mounts and Mount Options

August 22, 2021

As time goes by, NFS mounts multiply like rabbits. Added by many different people over the years, these entries present a dizzying variety of mount options – most are a copy-paste job that makes little sense. All this variety inevitably results in performance issues that are difficult to pin down.…Read More

Automatic File Backups in VIM

August 17, 2021

Having to undo stupid changes to config files is an unfortunate side effect of too few sysadmins supporting too many servers. The VIM editor has some built-in file backup options. However, I find these options very limited and generally not particularly well suited to sysadmin work. A solution has been…Read More

Joining Text Files and Data Columns

July 28, 2021

When working with application logs and other text files, it is often useful to view the contents of different source files side-by-side. Here we will take a quick look at various command-line methods for joining data columns from different files. Let’s start with a simple example: we have these three…Read More

Automating Web Page Screenshots

July 13, 2021

Originally published July 13, 2018 @ 2:25 pmAutomatic Web page screenshots are commonly used for various monitoring tasks, such as detecting copyright infringement, website defacement, and other legal and security matters. Automatic screenshotting can also be a useful tool for researchers, developers, and journalists. There are free and open-source tools…Read More

Convert Color Text to Images in Bash

June 4, 2021

The textmg is a cool little CLI tool written by jiro4989 – a systems engineer from Japan – that allows you to convert the color output in a terminal window to an image file. I find this very useful when sharing code snippets on social media and when writing documentation.…Read More

The Future of Spaghetti Code

May 30, 2021

Originally published May 30, 2018 @ 12:59 amIn his new book “The Future of Work: Robotics, AI, and Automation”1, Darrell West of the Brookings Institution makes some very extravagant predictions. Here’s a short but entirely sufficient summary from the book’s presentation by Brennan Hoban: AI is expected to be better…Read More

AWS CLI Cheat Sheet

May 21, 2021

Originally published May 21, 2018 @ 10:18 pmThe installation and configuration process for AWS CLI is fairly simple. The package itself is installed with pip (yum -y install python-pip): pip install awscli --upgrade --user Selecting what you need from the output can be accomplished via awscli filters and queries; using…Read More

Copying X11 Magic Cookies

May 15, 2021

Originally published May 15, 2018 @ 10:03 amI rarely use GUIs, but when I do, it’s from CLI and every time I run into the annoying MIT-MAGIC-COOKIE-1 data did not match error. It’s easy to fix, but it happens to me so rarely that between the fixes I forget how…Read More

Verify Network Port Access

May 13, 2021

Originally published May 13, 2018 @ 8:53 pmThere are several tools you can use to verify access to a remote network port: nc, tcping, telnet. Unfortunately, nc from the netcat package has been replaced by the one from nmap, which lacks the -z option, making it useless for non-interactive applications. A partial workaround…Read More

Solving Crossword Puzzles from CLI

May 11, 2021

Linux command-line tools provide access to a wealth of dictionaries, encyclopedias, thesauri, directories, and other reference sources. Learning to use these tools is a worthwhile endeavor even if solving crossword puzzles is not your favorite pastime. Let’s start with installing the various tools we’ll be discussing in this article: apt…Read More

Deleting Hidden Files

May 7, 2021

Originally published May 7, 2018 @ 10:33 amThis simplest of problems just never fails to find a new victim. For whatever reason you want to delete all hidden files in the current directory and subfolders. Without much thinking you just type rm -rf .* Here’s a classic example of one…Read More

Longwood Gardens, April 2018

April 30, 2021

Originally published April 29, 2018 @ 9:17 pmIt’s not far and I buy a yearly pass, so, when there’s nothing better to photograph, I take photos of pretty flowers. Gets me a few “likes” on Facebook…

Quickly Grow tmpfs filesystem

April 29, 2021

Originally published April 29, 2018 @ 7:08 pmJust a quick command to double the size of the /tmp filesystem that uses tmpfs. This is  for those situations when you can’t be bothered to think. df -hlP /tmp && (( s = `df -lP /tmp | grep ^tmpfs | awk '{print…Read More

Late Night Rant: Agile

April 17, 2021

Originally published April 17, 2018 @ 10:56 pmCollabNet VersionOne has released it’s 12th annual “State of Agile” report. The survey involved more than 1,400 software professionals in various roles and industries over the fourth quarter of 2017. Only 12% responded that their organizations have a high level of competency with…Read More

Duck Duck Go Search from Shell

April 11, 2021

Originally published April 11, 2018 @ 4:25 pmThe ddgr python script is a command line interface for Duck Duck Go  – a privacy-oriented search engine that, unlike Google, will not give away your data to the likes of Cambridge Analytica. In the past year Duck Duck Go has grown and…Read More

Document Conversion with Unoconv

April 4, 2021

Originally published April 3, 2018 @ 2:07 pmThe other day I ran into the “Flexible Import/Export” article by Bruce Byfield in the March 2018 issue of Linux Pro Magazine and thought it could use some more detail. So here’s some more detail. The unoconv utility is a part of LibreOffice.…Read More

How Not to Prepare for a SysAdmin Interview

March 22, 2021

Originally published March 21, 2018 @ 12:26 amThe Linux Foundation just gave birth to seven supposedly interesting tips on how to prepare for a Linux SysAdmin job interview. Unfortunately, the research behind all this probably excellent advice was based on interviewing hiring managers – the people who, despite the title,…Read More