Systemd on Linux Security

Resolving DNS Issues with resolvectl and systemd-resolved in a Home Network

Mon, 15 Jun 2026 09:54:03 +0200

Introduction to DNS Resolution

When setting up a home network, DNS resolution is one of those critical components that can be a real pain to troubleshoot. I’ve seen this go wrong when people are new to Linux, so let’s dive into how to use resolvectl to resolve DNS issues with systemd-resolved.

Understanding systemd-resolved

systemd-resolved is a system service that handles DNS resolution, among other network-related tasks. It’s part of the systemd suite and is widely used in many Linux distributions, including Ubuntu, Debian, and Fedora. The real trick is that systemd-resolved provides improved DNS security and better support for modern DNS protocols like DNS over TLS (DoT) and DNS over HTTPS (DoH). Don’t bother with trying to use it without understanding these benefits, as they’re a key part of what makes systemd-resolved so useful.

Troubleshooting Slow Network Connectivity with ss and resolvectl on Linux

Sun, 14 Jun 2026 08:16:06 +0200

Introduction to Network Troubleshooting

I’ve seen my fair share of slow network connectivity issues on Linux, and having the right tools at your disposal can make all the difference. Two tools that I rely on are ss and resolvectl, which can help you diagnose and troubleshoot network issues. In this article, we’ll explore how to use these tools to identify and potentially fix slow network connectivity problems.

Understanding `ss`

The ss command is a replacement for the traditional netstat command, and it provides more detailed information about network connections, including TCP, UDP, and Unix domain sockets. To get started with ss, you can use the following command to display all active connections:

Taming Disk-Hungry Logs with systemd's Persistent Journal and Log Rotation

Sat, 13 Jun 2026 11:46:55 +0200

Introduction to Log Management

I’ve seen log management become a major headache for many Linux administrators. Logs are essential for diagnosing issues, detecting security threats, and optimizing system performance, but they can grow rapidly and consume significant disk space. In practice, this can lead to performance issues and even system crashes. To avoid this, we can use systemd’s persistent journal and log rotation features.

Understanding systemd’s Journal

Systemd’s journal is a centralized logging system that collects log messages from various system components, including systemd services, kernel messages, and application logs. The real trick is to configure it to use persistent storage, so logs aren’t lost upon system reboot. By default, the journal stores log messages in a volatile storage area, which isn’t very useful for long-term log management.

Using systemd to Manage and Rotate Logs for Forgotten System Services

Fri, 12 Jun 2026 08:50:25 +0200

Introduction to Log Management with systemd

I’ve seen many Linux admins struggle with log management, especially when it comes to system services that are often overlooked. Systemd is a powerful system and service manager that provides a wide range of features, including process management, dependency handling, and log management. In this article, I’ll focus on using systemd to manage and rotate logs for system services.

Understanding systemd Logs

The real trick is to understand how systemd logs work. Systemd logs are stored in a binary format, which can be read using the journalctl command. This command provides a powerful way to filter, search, and manage system logs. By default, systemd stores logs in /var/log/journal, but this can be configured to use a different location. Don’t bother with trying to read the binary logs directly - just use journalctl.

Taming systemd Timer Services to Run Your Daily Backup at a Reasonable Hour

Tue, 09 Jun 2026 09:05:53 +0200

Introduction to systemd Timer Services

I’ve been using systemd timer services for years to schedule tasks on my Linux systems, and I have to say, they’re a game-changer. Most Linux distributions, including Debian, Arch Linux, and OpenSUSE, use systemd as their default init system, so it’s worth learning how to use them. In this article, I’ll show you how to use systemd timer services to run daily backups at a reasonable hour.

Taming systemd-resolved: Troubleshooting DNS leaks and resolving domain name surprises on Linux desktops and servers

Fri, 05 Jun 2026 10:35:34 +0200

Introduction to systemd-resolved

I’ve seen systemd-resolved become a crucial part of many Linux distributions, including Ubuntu, Debian, and Fedora, as of 2026. It’s designed to provide a robust and secure way to resolve domain names on Linux systems. However, like any complex system, it can sometimes behave unexpectedly, leading to DNS leaks and domain name resolution surprises.

Understanding DNS Leaks

A DNS leak occurs when your system sends DNS queries to an unintended DNS server, potentially revealing your browsing history and online activities to third parties. This can happen when your system is configured to use a specific DNS server, but systemd-resolved is not properly configured to respect this setting. Don’t bother with manually trying to diagnose DNS leaks - just use online tools such as dnsleaktest.com or ipleak.net to check for them.

Taming systemd-resolved: How to Configure DNS Settings for Split Horizon Environments

Thu, 04 Jun 2026 11:14:28 +0200

Introduction to systemd-resolved

I’ve seen many Linux admins struggle with configuring DNS settings for split horizon environments. systemd-resolved, a DNS resolver component of the systemd suite, can make life easier. In this article, I’ll walk you through how to configure DNS settings for split horizon environments using systemd-resolved.

Understanding Split Horizon Environments

Split horizon environments are network setups where multiple DNS servers provide different answers for the same domain name, depending on the client’s location or network. I’ve encountered this in organizations with multiple offices or data centers, where different DNS servers serve different locations. For example, a company with offices in the US and Europe might have two separate DNS servers, one for each region, providing different IP addresses for the same domain name.

Rescuing a Linux System Stuck in Emergency Mode: A Step-by-Step Recovery Guide

Wed, 03 Jun 2026 11:47:11 +0200

Introduction to Emergency Mode

I’ve seen this go wrong when a Linux system encounters a critical issue during boot - it may enter Emergency Mode. This mode provides a minimal environment for troubleshooting and recovery. With many Linux distributions, including Debian and Arch Linux, updating their boot processes to use systemd, understanding how to rescue a system stuck in Emergency Mode is crucial.

Identifying the Issue

To rescue a system in Emergency Mode, you first need to identify the cause of the issue. Don’t bother with guessing - check the system logs, which are usually available in the /var/log directory. I usually start with the journalctl command to view the system logs:

Troubleshooting Failed Mounts at Boot Time with systemd and fstab

Tue, 02 Jun 2026 09:15:54 +0200

Introduction to Troubleshooting Failed Mounts

When I’m dealing with a Linux system that won’t boot properly, one of the first things I check is the mount points. systemd and the /etc/fstab file are crucial in this process, but issues can still arise, leading to failed mounts and potential system instability. In this article, I’ll walk you through practical steps to troubleshoot and resolve failed mounts at boot time, focusing on systemd and fstab configurations.

Taming Disk-Hungry Logs with systemd-journald and logrotate

Mon, 01 Jun 2026 10:10:58 +0200

Introduction to Log Management

I’ve seen log files grow out of control and consume disk space, affecting system performance. To tame disk-hungry logs, I recommend using systemd-journald and logrotate. These tools help manage log data, making it easier to troubleshoot, debug, and perform security audits.

Understanding systemd-journald

systemd-journald is a system service that collects and stores log messages from various sources. It provides a centralized logging system, which I find more efficient than traditional text-based log files. To view log messages, use the journalctl command:

Rescuing a Broken Linux System with a systemd Emergency Mode Shell

Sun, 31 May 2026 08:26:25 +0200

Introduction to Emergency Mode

I’ve seen this go wrong when a Linux system encounters a critical issue during boot - it can be a real headache. But, thankfully, Linux has a built-in safety net called emergency mode. This mode kicks in when there’s a failed filesystem check or an inability to mount a necessary partition, providing a minimal environment for troubleshooting and repair. With the advancements in Linux, understanding how to use emergency mode is crucial for system administrators and users alike.

Troubleshooting DNS Leaks with systemd-resolved and resolv.conf on a Small Linux Server

Fri, 29 May 2026 08:36:48 +0200

Introduction to DNS Leaks

I’ve seen DNS leaks cause issues on even the most secure Linux servers. Ensuring your DNS setup is solid is crucial, and one common problem is a DNS leak, where your system inadvertently reveals your DNS queries to unauthorized parties. In this article, I’ll walk you through troubleshooting DNS leaks using systemd-resolved and resolv.conf on a Linux server.

Understanding systemd-resolved

systemd-resolved is a powerful tool that provides DNS resolution capabilities. It’s designed to be a caching, validating DNS resolver that can also handle DNSSEC validation. To check if systemd-resolved is running on your system, use the following command:

Debugging systemd Service Startup Failures with systemd-analyze and Journalctl

Thu, 28 May 2026 11:31:56 +0200

Introduction to Debugging systemd Services

I’ve seen this go wrong when you’re trying to troubleshoot issues with your Linux system - those pesky systemd services can be a real pain. They’re the backbone of your system, managing everything from network connections to system logging. Debugging these services can be a daunting task, especially for those new to Linux administration. Fortunately, systemd provides two powerful tools to help you diagnose and resolve issues: systemd-analyze and journalctl.

Taming Split DNS Chaos with systemd-resolved and Local Hostname Resolution

Wed, 27 May 2026 08:34:11 +0200

Introduction to Split DNS Chaos

I’ve seen this go wrong when working with multiple networks or self-hosted services: split DNS configurations can become a real headache. Luckily, many Linux distributions have started adopting systemd-resolved as the default DNS resolver, which makes managing split DNS scenarios much simpler. In this article, I’ll walk you through how to use systemd-resolved for local hostname resolution and taming that split DNS chaos.

Understanding systemd-resolved

The real trick is understanding how systemd-resolved works. It’s a systemd component that provides DNS resolution and caching, and it can be configured to use multiple DNS servers and handle split DNS scenarios with ease. To check if systemd-resolved is enabled on your system, run the following command:

Troubleshooting Slow DNS Lookups with systemd-resolved and resolvectl

Mon, 25 May 2026 08:57:59 +0200

Introduction to Troubleshooting Slow DNS Lookups

I’ve seen slow DNS lookups bring Linux systems to a crawl, and with our increasing reliance on online services, efficient DNS resolution is crucial. This article focuses on troubleshooting slow DNS lookups using systemd-resolved and resolvectl, which are integral to many modern Linux distributions.

Understanding systemd-resolved

systemd-resolved is a system service that provides DNS resolution, replacing traditional implementations like glibc’s resolver. It offers improved security, better DNSSEC handling, and efficient management of multiple DNS servers. To check if it’s running on your system, use:

Taming systemd-resolved: Avoiding DNS Leaks and Surprises with Split DNS Configurations

Sun, 24 May 2026 10:21:18 +0200

Introduction to systemd-resolved

I’ve worked with Linux systems for years, and one thing that’s become increasingly important is DNS resolution. systemd-resolved is a DNS resolver component of the systemd suite, designed to provide a flexible and secure way to resolve domain names. It was introduced in systemd version 216, released in 2015, and has since become a standard component in many Linux distributions. By default, systemd-resolved uses a split DNS configuration, which can sometimes lead to DNS leaks and unexpected behavior. I’ve seen this go wrong when a system has multiple network interfaces or connections, each with its own DNS resolver configuration.

Using systemd to Manage and Rotate Log Files Without Running Out of Disk Space

Sat, 23 May 2026 11:26:20 +0200

Introduction to Log Rotation with systemd

I’ve seen log files consume entire disks, bringing systems to a grinding halt. That’s why log rotation is crucial - it ensures your logs don’t get out of control. With systemd, you’ve got a robust mechanism for managing and rotating logs. In this article, I’ll dive into using systemd for log rotation, covering its benefits, configuration, and some practical examples.

Understanding systemd’s Role in Log Rotation

systemd’s journald is a game-changer for log management. It collects and stores log messages from various sources, including systemd services, kernel messages, and other system components. This centralized logging system makes it easier to manage and rotate logs. By leveraging systemd’s capabilities, you can configure log rotation to suit your specific needs, keeping your system stable and secure.

Taming systemd-resolved: Tips for Troubleshooting and Customizing DNS Resolution on Linux

Fri, 22 May 2026 10:04:50 +0200

Introduction to systemd-resolved

I’ve been using systemd-resolved for a while now, and I have to say, it’s a big improvement over traditional DNS resolvers. As of 2026, many Linux distributions, including Ubuntu, Debian, and Fedora, have adopted systemd-resolved as the default DNS resolver. While it offers several benefits, including improved security and performance, some users may encounter issues or require customization to suit their specific needs. Don’t bother with trying to disable it, though - it’s usually worth the effort to get it working right.

Using rsync and systemd to Automate Offsite Backups of Selected Config Files and User Data

Thu, 21 May 2026 10:49:01 +0200

Introduction to Automated Offsite Backups

As a Linux user, you’ve probably learned the hard way how important it is to protect your configuration files and user data from loss or corruption. I’ve seen this go wrong when a disk fails or a configuration change goes awry. One way to ensure the integrity of this data is to set up automated offsite backups. In this article, we’ll explore how to use rsync and systemd to create a reliable and efficient backup system.

Using jq to Parse and Manipulate JSON Logs from systemd-journald

Tue, 19 May 2026 08:58:34 +0200

Introduction to jq and systemd-journald

I’ve found that working with Linux systems often involves digging through logs to troubleshoot issues. systemd-journald is a key component in this process, collecting and storing log messages from various sources. Since these logs are often in JSON format, tools like jq become incredibly useful for parsing and manipulation. In this article, I’ll walk you through how to use jq to parse and manipulate JSON logs from systemd-journald.

Troubleshooting systemd Service Startup Failures with Dependency Ordering and Journalctl

Mon, 18 May 2026 10:30:29 +0200

Introduction to systemd Service Troubleshooting

I’ve seen this go wrong when services fail to start due to complex dependency ordering and logging issues. systemd, with its powerful tools for diagnosing problems, makes it easier to identify and fix these issues. In this article, we’ll focus on practical examples of using dependency ordering and journalctl to troubleshoot systemd service startup failures.

Understanding systemd Dependencies

systemd services are defined in unit files, typically located in /etc/systemd/system/ or /usr/lib/systemd/system/. These files specify the service’s dependencies, which are crucial for determining the order in which services start. Dependencies are defined using directives like Requires, Wants, Before, and After. For instance, a web server service might require the network service to be started before it can start itself.

Taming Log Rotation in systemd: A Practical Approach to Preventing Disk Bloat

Sun, 17 May 2026 10:14:26 +0200

Introduction to Log Rotation

I’ve seen this go wrong when log files grow out of control, filling up the disk and causing system instability. That’s why log rotation is a crucial aspect of Linux system maintenance. With many Linux distributions, including Debian and Arch Linux, adopting systemd as their default init system, understanding how to manage log rotation in a systemd environment is essential. In practice, this means getting familiar with systemd-journald, the component responsible for collecting and storing log messages.

Taming systemd Service Restart Behavior with RestartSec and TimeoutStartSec

Sat, 16 May 2026 08:13:26 +0200

Introduction to systemd Service Restart Behavior

I’ve seen this go wrong when a service fails and systemd keeps restarting it, causing more harm than good. To avoid this, it’s essential to understand how systemd handles service restarts. Systemd is a core component of most modern Linux distributions, responsible for managing system services, including their startup, runtime, and shutdown. One of the key aspects of systemd service management is its ability to automatically restart services that fail or terminate unexpectedly. However, this behavior can sometimes lead to unintended consequences, such as a service restarting indefinitely in a failed state. To mitigate this, systemd provides two important directives: RestartSec and TimeoutStartSec.

Systemd on Linux Security

Resolving DNS Issues with resolvectl and systemd-resolved in a Home Network

Introduction to DNS Resolution

Understanding systemd-resolved

Troubleshooting Slow Network Connectivity with ss and resolvectl on Linux

Introduction to Network Troubleshooting

Understanding ss

Taming Disk-Hungry Logs with systemd's Persistent Journal and Log Rotation

Introduction to Log Management

Understanding systemd’s Journal

Using systemd to Manage and Rotate Logs for Forgotten System Services

Introduction to Log Management with systemd

Understanding systemd Logs

Taming systemd Timer Services to Run Your Daily Backup at a Reasonable Hour

Introduction to systemd Timer Services

Taming systemd-resolved: Troubleshooting DNS leaks and resolving domain name surprises on Linux desktops and servers

Introduction to systemd-resolved

Understanding DNS Leaks

Taming systemd-resolved: How to Configure DNS Settings for Split Horizon Environments

Introduction to systemd-resolved

Understanding Split Horizon Environments

Rescuing a Linux System Stuck in Emergency Mode: A Step-by-Step Recovery Guide

Introduction to Emergency Mode

Identifying the Issue

Troubleshooting Failed Mounts at Boot Time with systemd and fstab

Introduction to Troubleshooting Failed Mounts

Taming Disk-Hungry Logs with systemd-journald and logrotate

Introduction to Log Management

Understanding systemd-journald

Rescuing a Broken Linux System with a systemd Emergency Mode Shell

Introduction to Emergency Mode

Troubleshooting DNS Leaks with systemd-resolved and resolv.conf on a Small Linux Server

Introduction to DNS Leaks

Understanding systemd-resolved

Debugging systemd Service Startup Failures with systemd-analyze and Journalctl

Introduction to Debugging systemd Services

Taming Split DNS Chaos with systemd-resolved and Local Hostname Resolution

Introduction to Split DNS Chaos

Understanding systemd-resolved

Troubleshooting Slow DNS Lookups with systemd-resolved and resolvectl

Introduction to Troubleshooting Slow DNS Lookups

Understanding systemd-resolved

Taming systemd-resolved: Avoiding DNS Leaks and Surprises with Split DNS Configurations

Introduction to systemd-resolved

Using systemd to Manage and Rotate Log Files Without Running Out of Disk Space

Introduction to Log Rotation with systemd

Understanding systemd’s Role in Log Rotation

Taming systemd-resolved: Tips for Troubleshooting and Customizing DNS Resolution on Linux

Introduction to systemd-resolved

Using rsync and systemd to Automate Offsite Backups of Selected Config Files and User Data

Introduction to Automated Offsite Backups

Using jq to Parse and Manipulate JSON Logs from systemd-journald

Introduction to jq and systemd-journald

Troubleshooting systemd Service Startup Failures with Dependency Ordering and Journalctl

Introduction to systemd Service Troubleshooting

Understanding systemd Dependencies

Taming Log Rotation in systemd: A Practical Approach to Preventing Disk Bloat

Introduction to Log Rotation

Taming systemd Service Restart Behavior with RestartSec and TimeoutStartSec

Introduction to systemd Service Restart Behavior

Understanding `ss`