File system permissions are at the root of every modern operating system and, Linux is no exception to this rule. While some users may not be well versed with how to apply proper permissions or, need assistance with the discovery of files, folders and configurations that may be overly shared this document aims to demystify Linux file permissions, how to find improper permissions and how to properly calculate permissions.

An introduction to utilizing auditd to detect malicious activity on a Linux system that may be under attack or, where the attacker has already gained access to the machine. This article looks at collecting the log information into /var/log/audit/audit.log.

Secure shell is the primary means of access for a Linux or, Unix host. Many times attackers will not only use ports: 22, 222, 2222 as a means of identifying a remote system as a Linux / Unix flavor but also attempt to use variations of user names (admin, root, administrator, test, etc.) to hammer your SSH server in order to gain a foothold within your environment. This document helps address some of the security concerns when running SSH.

This article walks defenders through the steps to protect a Linux system running PHP against PHP shells that have been uploaded to a remote host.