File Permissions

RuntimeDirectoryMode setting

Harden system and user services by configuring systemd units with more strict file permissions using the unit setting RuntimeDirectoryMode.

Set default file permissions on Linux with umask

Learn how to use umask to set the default file permissions in Linux. We look at examples, including how and where to implement them.

Understanding the output of the stat command

Learn everything about the output that the stat command returns. Great for forensics, intrusion detection, and system administration.

How to change file permissions

Learn how to change the file permissions of files and directories on a Linux system. Follow the examples and make your system more secure.

Linux file permissions

Learn the basics of file permissions on Linux systems and filesystems such as ext4, XFS, and ZFS. Guided by examples and common Linux tools.

Introduction in Linux file permissions

Learn the basics of how a Linux system applies file permissions. We look at examples to demystify the permissions mean and learn to troubleshoot common issues.

How to find hard links or files that point to a specific file

Learn how to find hardlinks on a file system or which files they have in common. We will use the find command to get this information quickly available.

Changing file permissions on macOS (and using flags)

Using file flags on macOS. While performing system hardening on macOS, you may encounter a typical chmod error. Learn how to fix this type of error

File permissions of the /etc/shadow password file

The /etc/shadow file is one of the most important files on Linux. Got an issue with the file permissions of your /etc/shadow password file? Look no further!

Linux Capabilities: Hardening Linux binaries by removing setuid

Setuid binaries may be a risk for the system. We will investigate how to remove the setuid bit and use Linux capabilities instead, to reduce the risks.

PCI DSS (v3) Linux: Restrict log file viewing (A.1.2.d)

Linux users who want to compliant with PCI DSS have to restrict log file viewing to only the owner. Learn how to achieve this.

Plus sign in ls output

When file access control lists, or ACLs are being used, the output of ls will change. Learn about the additional plus sign in its output.

Conducting a Linux Server Security Audit

Performing a Linux server security audit can be a time consuming process. In this article the most important parts are explained including automation.