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January 6, 2020 – 12:38 am

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:

The key to getting this setup working well is to weed …

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Appending Filenames

December 22, 2019 – 9:51 pm
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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 …

Bulk-Adding IPTables Rules

December 12, 2019 – 9:46 pm
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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 …

Windows 10 Upgrades

December 6, 2019 – 9:44 pm
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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.

Working with iptables Logging

November 30, 2019 – 9:41 pm
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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

November 29, 2019 – 9:40 pm
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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 …

CD/DVD-to-ISO Helper Script

November 27, 2019 – 9:39 pm
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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 …

Copying Data in a Restricted Environment

August 17, 2019 – 8:04 pm
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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 …

Sending Windows Logs to Remote Syslog

July 6, 2019 – 11:21 am
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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

July 3, 2019 – 11:19 am
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Many recent publications , , suggest the iPhone is full of security holes threatening your privacy. The threat seems to be coming not so much from the phone’s operating system, but from the apps, …

Squeezing Video Files

June 30, 2019 – 11:16 am
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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 …

Finding Passwords in Logs and Shell History

June 27, 2019 – 11:15 am
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Sooner or later it will happen: you type something after which you expect a password prompt then, without looking, you type the password. However, you fat-fingered the first command, and your password ended up in …

Anatomy of Internet Bullshit

June 25, 2019 – 11:12 am
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Here’s an oldie from two years ago that reared its ugly head on Pocket: Starting Your Day on the Internet Is Damaging Your Brain, by Srinivas Rao. The author presents his personal opinion that reading …

Creating a Chroot Jail for SSH Access

April 17, 2019 – 4:51 pm
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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 Unix Oriental

April 14, 2019 – 4:16 pm
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Placed quite appropriately in the “Security” category – my favorite Oriental cocktail recipe. Distinguishing it from the classic preparation, are absence of sweet vermouth and lime juice, as well as addition of just a couple …

Encrypting Log Data During Log Rotation

April 9, 2019 – 4:12 pm
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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 …

Late Night Rant: Facebook

March 25, 2019 – 4:15 pm
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According to media reports, since 2012, millions of Facebook and Instagram logins and plaintext passwords have been sitting on some internal Facebook system, accessible by  thousands of the company’s employees.

File Compression Testing

January 27, 2019 – 5:29 pm
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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; …

Killing Process Network Access

January 27, 2019 – 4:45 pm
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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.

Keeping Abreast with Filesystem Changes

January 17, 2019 – 4:39 pm
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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.

The Facebook Fracas

January 9, 2019 – 4:48 pm
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The 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 ever existed.

Find Large Folders

January 9, 2019 – 4:37 pm
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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 a file to delete…

The Future of Spaghetti Code

August 18, 2018 – 4:20 pm
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In 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 …