sysctl tuning on Linux

While most Linux Kernels nowadays come with nice sysctl defaults, there’s always room for improvement. Some parameters can be used for performance tuning, others can be critical for security hardening. What is sysctl? sysctl is an interface to view and dynamically change parameters in Linux and other *NIX operating systems. In Linux, most of the dynamic Kernel settings can be […]

TCP connection states

TCP is the abbreviation for Transmission Control Protocol. It is one of the core protocols in the internet protocol suite and provides a reliable protocol to communicate in computer networks. Nearly every Internet-connected device “talks” TCP and the whole Internet relies on it.

Docker Pull Deprecation for v1.5 clients

A while ago, Docker announced that Docker pull requests from version 1.5 and earlier clients will no longer function as of December 15. While push requests have been disabled since Nov 19, pull requests were disabled for the Docker Hub today as well.

Ansible Modules – shell vs. command

In the Ansible Core are a lot of Ansible modules included for almost all use cases. On this page are all modules listed and described with the available options and some examples. Some Ansible modules are on the first view quite similar and can be used for the same purpose, but often are there some crucial […]

Compare command outputs with process substitution

Every sysadmin knows the situation, if he has to compare the output of some commands. Most of us save the output of the commands in a temporary file, compares these files with the diff binary and afterwards delete the temporary files. In this blog post I’ll show you the usage of process substitution to get the differences of commands […]

Ansible Tower offline installation on a Red Hat system

A few days ago Ansible released a new version of their enterprise product Ansible Tower. It’s a web interface on top of the ansible core and offers a lot of useful features. In the release notes is a new topic listed that is an important requirement for some customers of us, bundled installation support. It’s now possible […]

Calling Ansible handlers based on OS distributions

Sometimes you’ve got an Ansible task that should notify another task after a change. In Ansible this is called a handler and a description can be found here. Mostly the handler can be defined OS-independent. In this blog post, we show you, how to use a list of handlers for different OS distributions.

Deploying SSL private keys with Ansible

When you’re using Ansible or any other configuration management tool, you might come in contact with deploying SSL certificates sooner or later. While deploying public SSL certificates isn’t a security issue at all, the deployment of private keys become more critical – at least if you want to deploy them securely.