Linux system hardening: adding hidepid to /proc

Hiding processes for other users The pseudo-filesystem /proc contains a lot of useful information for the system administrator. It also shares a lot to normal users on the system. We can change what can be seen by using the right mount options. When looking in /proc you will discover a lot of files and directories. A lot of these directories are just numbers and represent the information about a particular process ID (PID). By default, Linux systems are deployed to allow […]

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Linux History: How Dot Files Became Hidden Files

The history of hidden files Ever wondered why there are files on your Linux system, starting with a dot? The short answer: they are shortcuts. The story begins many years ago when the first file systems were created on UNIX. To allow easy navigation, a single file with a dot (.) was added to each directory. Secondly, a double dot file (..) was added to easily move up in the directory structure. As these files had no real data in them, […]

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Using xattrs or Extended Attributes on Linux

Using xattrs or Extended Attributes on Linux Extended attributes, xattrs for short, are an extensible mechanism to store metadata along files. In other words, they describe some additional properties of the file. Normally this information is limited, like ownership and dates. With xattrs more information can be stored about the file. Support for xattrs Not all file systems have support for xattrs, but nowadays the most common ones support it (EXT4, Btrfs, ReiserFS, JFS and ZFS). To determine if your […]

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