Timeline
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
Working with ffmpeg on Multi-Core Systems
While ffmpeg has multithreading capability, getting the best performance on multi-core systems calls for something more than just playing with the -threads option.
IMDb Movie Title Parser in Bash
This is an update to the IMDb parser I wrote years back. From time to time IMDb makes small changes to their setup that break my script. This time they decided to start blocking curl, or so it would seem. Even using a fake user-agent string doesn't help. But wget…Read More
Sending Windows Logs to Remote Syslog
Nothing fancy here: just a quick note on directing Windows event logs and select application logs to a remote syslog server.
Plugging iPhone’s Privacy Holes
Many recent publications [efn_note]Gallagher, Sean, and Utc. “Dozens of IOS Apps Surreptitiously Share User Location Data with Tracking Firms.” Ars Technica, 10 Sept. 2018, arstechnica.com/information-technology/2018/09/dozens-of-ios-apps-surreptitiously-share-user-location-data-with-tracking-firms/. [/efn_note], [efn_note]Stern, Joanna. “iPhone Privacy Is Broken...and Apps Are to Blame.” The Wall Street Journal, Dow Jones & Company, 31 May 2019, www.wsj.com/articles/iphone-privacy-is-brokenand-apps-are-to-blame-11559316401. [/efn_note], [efn_note]Fowler,…Read More
Managing Mapped Network Drives in Windows
Windows, that epitome of operating system excellence, just loves hammering away at mapped network drives whenever it sniffs even a whiff of network connectivity. Any network, mind you—right or wrong. Predictably, this stubborn attachment leads to performance hiccups and random hangs, all because Windows can't resist reaching out to drives…Read More
LLM Collapse Explained
Overview [audio mp3="https://www.igoroseledko.com/wp-content/uploads/2025/05/v6y03s0z22gigydnwnbqf41qadf.mp3"][/audio] Model collapse in large language models (LLMs) occurs when models repeatedly train on their synthetic outputs, gradually reducing the diversity, accuracy, and alignment of generated content compared to original human-produced data. Detecting and measuring this issue is crucial to maintaining the quality of these models and avoiding…Read More
Squeezing Video Files
All that crap I've been saving from YouTube, Facebook and whatnot tends to add up. As quality is not a huge concern here (not that it was very high to begin with), optimizing those video files can recover a surprisingly significant amount of disk space. If you have CPU cycles…Read More
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
