Cheewai cynici

A Short IPv6 Guide for Home IPv4 Admins

This guide is for homelab admins who understand IPv4s well but find setting up IPv6 hard or annoying because things work differently. In some ways, managing an IPv6 network can be simpler than IPv4, one just needs to learn some new concepts and discard some old ones.

Let’s begin.

First of all, there are some concepts that one must unlearn from ipv4:

Concept 1

A funky shell thingy that I've never seen before

So you're in posix sh and you want to do the equivalent of this in bash:

foo | tee >(bar) >(baz) >/dev/null

(Suppose that bar and baz don't produce output. Add redirections where needed if that's not the case.)

Fedora 36 Post Installation (For Software Developers)

Top N things you should do after installing or upgrading to your new Fedora 36 workstation.

Settings

Change Hostname

CPU: percentage of limit

A lot of people land when trying to find out how to calculate CPU usage metric correctly in prometheus, myself included! So I'll post what I eventually ended up using as I think it's still a little difficult trying to tie together all the snippets of info here and elsewhere.

This is specific to k8s and containers that have CPU limits set.

To show CPU usage as a percentage of the limit given to the container, this is the Prometheus query we used to create nice graphs in Grafana:

sum(rate(container_cpu_usage_seconds_total{name!~".*prometheus.*", image!="", container_name!="POD"}[5m])) by (pod_name, container_name) /

As tested on Linux:

An SCM_RIGHTS ancillary message is "attached" to the range of data bytes sent in the same sendmsg() call.
However, as always, recvmsg() calls on the receiving end don't necessarily map 1:1 to sendmsg() calls. Messages can be coalesced or split.
The recvmsg() call that receives the first byte of the ancillary message's byte range also receives the ancillary message itself.
To prevent multiple ancillary messages being delivered

	Aerobase	Keycloak	WSO2 Identity Server	Gluu	CAS	OpenAM	Shibboleth IdP
OpenID Connect/OAuth support	yes	yes	yes	yes	yes	yes	third-party
Multi-factor authentication	yes	yes	yes	yes	yes	yes	yes
Admin UI	yes	yes	yes	yes	yes	yes	no
OpenJDK support	yes	yes	yes			yes	no
Identity brokering	yes	yes	yes
Middleware	NGINX, Wildfly	Wildfly, JBOSS	WSO2 Carbon	Jetty, Apache HTTPD	any Java app server	any Java app server	Jetty, Tomc

ⓘ This list is not meant to be exhaustive and is not guaranteed to be maintained. See the comments for updates and alternative options.

(Items in bold indicate possible concerns)

	Keycloak	WSO2 Identity Server	Gluu	CAS	OpenAM	Shibboleth IdP
OpenID Connect/OAuth support	yes	yes	yes	yes	yes	yes
Multi-factor authentication	yes	yes	yes	yes	yes	yes
Admin UI	yes	yes	yes	yes	yes	no
OpenJDK support	yes	yes	partial²	yes

	# ===================================================================== #
	# BASIC CONFIGURATION
	# ===================================================================== #

	# Arch: "default", "x86_64", "aarch64".
	# "default" corresponds to the host architecture.
	arch: "default"

	# An image must support systemd and cloud-init.
	# Ubuntu and Fedora are known to work.

	{
	"install": "pip3 install --user -r requirements.txt",
	"start": "PYTHONUNBUFFERED=true python3 server.py",
	"watch": {
	"ignore": [
	"\\.pyc$"
	],
	"install": {
	"include": [
	"^requirements\\.txt$"

	for node in $(knife search node "ohai_time:[* TO $(date +%s -d '30 days ago')]" -i); do
	knife client delete $node
	knife node delete $node
	done