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IPv4 Link Local Addresses in Fedora

A network link-local address is an address that is valid only for use within the network segment or the broadcast domain that a host is connected to. Link local addresses can be layer 2 or layer 3. For example, a 48-bit Ethernet MAC address is one form of a layer 2 link-local address. Link-local addresses are generally not guaranteed to be unique beyond a network segment. Because of this, layer 3 switches (routers) do not forward packets with layer 3 link-local addresses. For Layer 3 IPv4 link-local (IPv4LL) addresses, RFC3927 specifies the address block 169.254.0.0/16. Zero-configuration Networking (zeroconf) is a

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

Boycott Systemd

Finally people are beginning to wake up and understand that systemd and Lennart Poettering, who works for Red Hat, is a cancer that will destroy and splinter the Linux ecosystem. According to a new movement, boycottsystemd.org: It represents a monumental increase in complexity, an abhorrent and violent slap in the face to the Unix philosophy, and its inherent domineering and viral nature turns it into something akin to a “second kernel” that is spreading all across the Linux ecosystem. I could not agree more. systemd flies in the face of the Unix philosophy: “do one thing and do it well,”

Systemd the Operating System?

It appears that Lennard Poettering is a student of Adolf Hitler plan to invade the Sudetenland. Just let me do this and all will be well! Systemd was sold to the adoring masses on the basis that it would significantly speed up system startup and shutdown. That was a complete lie from the start. Systemd has not significantly improved system startup or shutdown times. Instead it has seriously complicated things for ordinary system administrators and integrators. Instead of a small number of initialization scripts, there are hundreds of configuration files and executables. Since then, systemd has spread like a cancer