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Revisiting Systemd D-Bus Interfaces

This blog looks in detail at systemd’s hostnamectl and timedatectl utilities and their associated daemons.

Control Group Subsystems in RHEL7

Control groups (cgroups) are a Linux kernel feature that enables you to allocate resources — such as CPU time, system memory, disk I/O, network bandwidth, etc. — among hierarchically ordered groups of processes running on a system. Initially developed by Google engineers Paul Menage and Rohit Seth in 2006 under the name “process containers”, it was merged into kernel version 2.6.24 and extensively enhanced since then. RHEL6 was the first Red Hat distribution to support cgroups. Cgroups provide system administrators with fine-grained control over allocating, prioritizing, denying, managing, and monitoring system resources. A cgroup is a collection of processes that


Project Atomic, a Red Hat sponsored project, features an interesting new update system for RPM-based Linux operating systems called OSTree (rpm-ostree) which has been developed by Colin Walters over the last couple of years. Evidently OSTree supports atomic updates to an OS although I am not sure how that actually works because there is a lot of marketing hype and buzz words associated with Project Atomic including Docker containers. In the default model, the RPMs are composed on a server into an OSTree repository, and client systems can replicate in an image-like fashion, including incremental updates. However, unlike traditional Linus

The Sunsetting of SHA-1

SHA-1 (Secure hash algorithm) is a 160-bit hash algorithm that is at the heart of many web security protocols such as Secure Sockets Layer (SSL) and Transport Layer Security (TLS) since shortly after it was developed by the NSA (National Security Agency) in 1995. In 2005, a professor in China demonstrated an attack that could be successfully launched against the SHA-1 function, suggesting that the algorithm might not be secure enough for ongoing use. Because of this, NIST immediately recommended federal agencies begin moving away from SHA-1 toward stronger algorithms. In 2011, NIST mandated that many applications in federal agencies