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; …
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![IMG_1941[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/IMG_19411-100x65.jpg "Killing Process Network Access")
![k0c1xg3f9erebub0aeel9842kih-1[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/k0c1xg3f9erebub0aeel9842kih-11-100x65.jpg "Installing t CLI power tool for Twitter")
![4bh5tzr851pq7wca4n9e6zus2fn[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/4bh5tzr851pq7wca4n9e6zus2fn1-100x65.jpg "Keeping Abreast with Filesystem Changes")
Security »
Late Night Rant: Facebook
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.
Measure DNS Server Performance
This is not an entirely proper way to benchmark a DNS server, but, in a pinch, it should give you some idea of its responsiveness and stability.
The Facebook Fracas
![gaabtjyr7kjlsqt1dsziphakwvj[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/gaabtjyr7kjlsqt1dsziphakwvj1-80x80.jpg "The Facebook Fracas")
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.
Generating and Running Multiple Scripts
![lqmqmqhf574z485f4ldembi9vtv[1]](https://i1.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/lqmqmqhf574z485f4ldembi9vtv1-80x80.jpg "Generating and Running Multiple Scripts")
Admittedly, this has a limited range of practical applications and is more of a scripting exercise. The command shown here generates a bunch of temporary scripts each containing the sleep command for up to one minute.
Removing Chef Server Installation
Just a quick note on how to completely remove (more or less) Chef server installation from a CentOS/RHEL box.
Auto-Update /etc/hosts
![rkhctxih1a1jdqh7x0cgs00ljh5[1]](https://i1.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/rkhctxih1a1jdqh7x0cgs00ljh51-80x80.png "Auto-Update /etc/hosts")
This was a silly solution to a silly problem, but may come in handy in the future for other things. A user process was establishing frequent connections to a handful of FQDNs. Not having any IP caching capability, every connection attempt was preceded by DNS lookup.
Find Large Folders
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…
Deleting Hidden Files
This 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 …
Quickly Grow tmpfs filesystem
Just 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.
Duck Duck Go Search from Shell
The 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 …
Obfuscating Shell Scripts
Unix shell scripting language is run by the command-line interpreter and, as such, can be read and understood by anyone with sufficient access and experience. Sometimes this is not a good thing. Sometimes you want …
The Mystery of a Hemisphere
To make this long (and embarrassing) story short: a friend’s kid had a homework assignment in geometry to calculate the surface area of a conjoined cone, a cylinder, and a hemisphere.
Raspbian ‘partitions on different devices’ Error
After downloading a Raspbian image and writing it to an SD card, you get the following error when trying to boot the Pi: “Could not expand filesystem, please try raspi-config or rc_gui. Boot and root …
Tmux Bootstrap Configuration
Just a list of commands to quickly configure tmux with some of the best (i.e. my favorite) plugins and options. Feel free to disagree – you may be right – but I don’t think so.
Find Large Files
Every time a filesystem is running out of space and I need to find something to delete, I end up googling the syntax for the find command to make sure it stays off NFS and …
Show Logged In Users During a Time Window
Let’s say you want to see who was logged in on the server during last weekend. This includes users who, say, logged in on Thursday and haven’t logged out until Saturday afternoon.
Extracting Email Addresses from TCP Streams
Here’s a quick example of using tshark to extract email addresses from TCP streams. Let’s say some application on your server is sending emails and you want to find out who is receiving those emails.
Export WP Posts and Sync to Sharepoint
Long story short: old wiki is overloaded and broken; new wiki is not a wiki but SharePoint – a glorified file server; people are forced to improvise and put documentation on a WP wiki; bosses …
Useful MySQL One-Liners
I am by no means an expert SQL programmer. Having said that, I’ve been using MySQL for a very long time. This is a collection of simple but useful SQL queries and MySQL configuration options. …
Plotting Log Data
While I am on the subject of selecting time ranges from logs, a practical application presented itself. A lonely server in a far-away land with a habit of running out of memory could only be …
Croncal – the Cron Calendar
The croncal is a clever Perl script that reads entries in your crontab and outputs a schedule, showing the time when cron jobs will run.
Install and Configure Etckeeper
Etckeeper is a handy tool that uses git to keep track of changes to anything in /etc (or any other folder you choose). It’s very simple to use and can help you quickly identify and undo stupid …
Using IPTables to Allow Access to Private Networks
Below is a quick example of how to use iptables to allow port access for all types of private networks. In this case we’re allowing access to ports 10000 and 20000, commonly used by webmin and usermin.
Commands & Shells »
Killing Process Network Access
![IMG_1941[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/IMG_19411-80x80.jpg "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
![k0c1xg3f9erebub0aeel9842kih-1[1]](https://i2.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/k0c1xg3f9erebub0aeel9842kih-11-80x80.jpg "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.
Applications »
AWS CLI Cheat Sheet
The installation and configuration process for AWS CLI is fairly simple. The package itself is installed with pip (yum -y install python-pip):
Late Night Rant: Agile
CollabNet 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 …
Data »
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.
Keeping Abreast with Filesystem Changes
![4bh5tzr851pq7wca4n9e6zus2fn[1]](https://i0.wp.com/www.krazyworks.com/wp-content/uploads/2019/01/4bh5tzr851pq7wca4n9e6zus2fn1-80x80.jpg "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.
Monitoring »
Automating Web Page Screenshots
Automatic 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 out there that can help you automate the task of creating Web page screenshots.
Automating Web Page Screenshots
Automatic 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, …
Networking »
Inventory Network Services with Nmap
With 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 and services.
Verify Network Port Access
There 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 …
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Igor
Sr. Unix SysAdmin with twenty years experience supporting Solaris, HP-UX, AIX, IRIX, and Linux servers in a large distributed environment.
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