Topic: Linux – Ctrl blog

GNU Parallel can do anything, but scripting may be the better option

2021-04-03T15:07:00Z

GNU Parallel is a utility that lets you run command jobs in parallel; on local and on remote hosts over the network. It’s incredibly powerful when you need something more flexible than xargs, and it’s especially useful with small computer clusters.

systemd application firewalls by example

2021-02-12T20:02:00Z

An application firewall, unlike a gateway (router) or system level firewall, is meant to limit the networking of a single application. It can be used to prevent a compromised service from seeing into the local network, prevent programs from calling home, plug metadata leaks, or more tightly control a program’s network access.

What’s with cp --reflink: failed to clone: Invalid argument?

2021-01-23T14:10:00Z

Most modern copy-on-write file systems, such as Btrfs and XFS, support file cloning. (OpenZFS being the notable exception.) However, the tools that support this space-saving innovation can be difficult to use. Here’s an example situation detailing how the simple copy (cp) command on Linux can make it hard to understand what’s going on.

How to resize ZRAM (compressed swap) managed by systemd/zram-generator

2020-11-13T04:45:00Z

Fedora Linux 33 was released last week with some interesting changes like switching the default file system to BtrFS, handing DNS resolution over to systemd-resolved, and enabling ZRAM instead of a swap partition by default. I’ll focus on the latter feature in this article.

TeamViewer RPM repo left door open for malicious packages

2020-11-02T15:50:00Z

Three months ago, I discovered a security vulnerability in TeamViewer RPM auto-updates on Linux. The vulnerability allowed an attacker-in-the-middle (AITM) to subvert the TeamViewer RPM package repository to install and execute arbitrary software with root permissions.