Timeline

Validating HTTPS Cache Peers for Squid
I have a squid proxy server that uses a long list of authenticated cache peers in a round-robin configuration. The process looks something like this:
Fuzzy Search with Linux
This is a quick look at several handy utilities that will allow you to find, navigate, and edit directories and files easily. This overview includes such tools as fzf, rg, fd-find, bat, and the fzf.vim plugin for VIM.
Updating PHP 5.6w to 7.1u on CentOS 6.10
This is mostly just a note to self. As I mentioned previously (probably more than once), I very much dislike systemd and will stick with CentOS 6 for as long as possible. Having said that, WordPress dashboard has been nagging me about having to update PHP. So here we go.
Analyzing atop Logs with atopsar
I have discussed atop previously but concentrated primarily on how to run it and how to collect data. Now I'd like to spend some time talking about ways to analyze the data collected with atop.
Sun Juan Mountains, Colorado
In July, some friends and I went on an 8,000-mile overlanding trip to Colorado, Utah, Wyoming, and South Dakota. One of the first stops was the Alpine Loop in Colorado's San Juan mountains. Here are some photos from there and other nearby areas we visited on our first week of…Read More
Appending Filenames
If you google how to append, say, current timestamp to the filename in Bash, almost every suggestion boils down to something really basic along the lines of mv $somefile $somefile_$(date +'Y%-%m-%d'). Technically, this is correct and, yet, this is not what was needed.
Basic Data Recovery in Linux
Have you noticed how the letters "e" and "r" are neighbors on your keyboard? And an unrelated question: do you know the difference between crontab -e and crontab -r commands? Look it up if you don't. Honestly, I've never used the crontab -r command in my many years as a…Read More
Renaming Files with exiftool, Part II
In the first part of this article, I went over the details of a process for renaming photos to include the geographic location in the filename. Some people asked if the same can be done for videos, and the answer is "probably."
Dealing with GitHub Desktop
GitHub Desktop is one of those terrible applications that I still have to use occasionally, much to my regret. I can't tell you if a five-year-old or a cat coded it, but this application with relatively straightforward functionality has more bugs than Florida.
Verifying SNMP Connectivity on Multiple Hosts
I needed to check if SNMP was accessible on whatever live servers that existed in a particular subnet. Here's a quick script to do this.
Selecting Time Ranges from Logs, Part 2
A couple of years ago I wrote an article about selecting specific time ranges from log files. I proposed two options: either convert all timestamps to epoch format (a CPU-intensive process) or rely on regex (limited to specific date/time periods). Here's a followup with a couple more methods. Perhaps a…Read More
Bulk-Adding IPTables Rules
I've been using my mod of this handy script to block countries with iptables. One issue with the script is that it is adding rules one-by-one using the iptables -A syntax. This is the proper way to add rules, but it does take a long while. And here's how you…Read More
Late Night Rant: Trump, Bolton, Iran, Saudis
Usually I try to keep politics out of my blog, but this time I just can't resist. A few days after Trump fires Bolton for being too tough on Iran (among other reasons), the supposedly Iranian-backed somebodies launched a daring and devastating attack, crippling Saudi Arabia's oil production.
Automatically Block Frequent Visitors
I had a few similar scripts floating around this site, but this one is a bit more all-inclusive and better organized. The script will analyze your firewall/whatever access log and block particularly active visitors.
Windows 10 Upgrades
I did the only sensible thing and disabled automatic updates on my two Windows 10 laptops. Microsoft's belated foray into the world of CI/CD for releasing Windows patches suffers from limited automated testing.
Server and Application Resiliency Testing
You are deploying a new application cluster and wonder how it will perform under less-than-ideal conditions: heavy system load, slow storage, network performance degradation. Application resiliency testing is integral to any application architecture but is often passed over because the process is considered overly complex and time-consuming. Here are some…Read More
Detecting Blurry Photos with ImageMagick
Here's a typical scenario: I go to a birthday party where everyone knows I'm a shutterbug, so I have to bring my camera. As time goes by and blood alcohol concentration rises and attention to detail declines, the photos become increasingly blurry. The trick is to take a lot of…Read More
Working with iptables Logging
Most commonly iptables is used to allow, block, or redirect connections. However, it also has a logging feature that can be very useful for network traffic analysis and system security.
Copying File Attributes Across Servers
To make long story short, had to fix someone's chmod -R 777 /. A late-night copy-paste fail, it would seem. Needless to say, console access is required, as SSH will not work with permissions on keys wide open. A prerequisite for the process below is to have a similar server…Read More
CD/DVD-to-ISO Helper Script
I can't recall the last time I needed to convert a CD to ISO. I have four laptops and not one even has a DVD drive. It took me a while to find an external drive and remember how to do this.
Longwood Gardens, August 2019
Longwood Gardens is an American botanical garden. It consists of over 1,077 acres of gardens, woodlands, and meadows in Kennett Square, Pennsylvania, United States in the Brandywine Creek Valley. It is one of the premier horticultural display gardens in the United States and is open to visitors year-round.
Analyzing Network Performance
Much of network performance analysis will be comparative in nature. Thus, seeing the output of multiple commands side by side can be quite useful. Bash has a useful little utility called pr and we'll make use of it.
Maintaining DNS Records
I've recently dragged all of my DNS records from Site5. It only took me six years to finally get off that godawful hosting service. In retrospect, keeping a better track of all DNS records would not have wasted time. Then again, I would not be a sysadmin if I wasn't…Read More
Copying Data in a Restricted Environment
Consider this not-so-hypothetical scenario: you have some data on server_a that you would like to copy to server_b. Unfortunately, these two servers cannot communicate with each other. Nor do they have access to any common network-mounted storage. Bummer. I do have a jumpbox from which I can SSH to either…Read More
Raising Dead Services
I suppose you may say all of this can be just as easily be done via systemd service config files. Well, yes and no. Yes, it can be done. And, no, not as easily. Not even close. Because systemd sucks by design. But this is a subject for another post.…Read More












































