Finding Passwords in Logs and Shell History
Sooner or later it will happen: you type something after which you expect a password prompt then, as a reflex, you type the password. However, you fat-fingered the first command, and your password ended up in clear text in your shell history, likely in the system log, and who knows…Read More
Creating a Chroot Jail for SSH Access
Just a quick collection of notes on - rather than a definitive guide to - setting up an SSH chroot jail on RHEL 6. The same should work on RHEL 7 and unrelated flavors. For the most part.
GPG Encryption QSG
It always seems that just enough time has passed since the last time I worked with GnuPG for me to forget not just the exact syntax of these commands completely but the workflow in general. Here are some basics about using GnuPG and managing keys. If you need to know…Read More
Encrypting Log Data During Log Rotation
Most log files do not contain personally-identifiable information or other sensitive data. And even if they do, encryption of all personal data is not mandatory under GDPR. Still, on occasion, for testing and troubleshooting purposes you may want to log potentially sensitive information. It would be a very good idea…Read More
DevOps Obfuscation
Some years ago I've been reading "DevOps in Straight English" by Magnus Hedemark [efn_note]“DevOps in Straight English - Part 1 of 2 - Enter the Buzzword.” RHD Blog, 20 Apr. 2018, developers.redhat.com/blog/2014/01/15/devops-in-straight-english-part-1-of-2/. [/efn_note] and encountered the Release Frequency vs. Risk chart that supposedly illustrated the advantages of DevOps. It seemed convincing…Read More
Gnuplot with Bash
OK, so both of these things have been around forever and will be around long after we're gone. It's worth your time to learn how to use the to together.
File Compression Testing
For some reason I haven't used zip much on Linux, sticking to the standard tar/gzip combo. But zip seems to be a viable alternative. While not as space-efficient, it is definitely faster; syntax is simple; and, if you need to share the archive with a Windows user, he doesn't have…Read More
Killing Process Network Access
Imagine 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.
Installing t CLI power tool for Twitter
The '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.
Keeping Abreast with Filesystem Changes
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.
Resizing Photos for Instagram
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
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 do offer suggestions as comments. If you fancy…Read More
Grouping Output of SSH via xargs
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
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.
Awk & sed Snippets for SysAdmins
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
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