Red Hat Enterprise Linux operating system freezes the Fedora a year or two before its release
CentOS Project is an community fork of RHEL, like a beta stream sitting between Fedora and Redhat
Fedora is the official open source version of RHEL, bleeding edge, test ground for RHEL features
AlmaLinux OS - Forever-Free Enterprise-Grade Operating System
Korora Project discontinued
Fedora
Package Management: RPM (dnf after 22)
Fedora (operating system) - Wikiwand
FedoraProject
The relationship between Fedora and Red Hat Enterprise Linux | Red Hat
Fedora 21 rolls three versions of Linux into one OS | InfoWorld
Fedora 25 stakes out leading edge, not bleeding edge | InfoWorld
Rawhide is the Fedora's rolling release
Releases/Rawhide - FedoraProject
Nobara Project
I Love Nobara Linux - Goodbye Manjaro and Distro Hopping - YouTube
CentOS
Firewall
CentOS Linux 7 以 firewalld 指令設定防火牆規則教學 - G. T. Wang
How To Open A Port In CentOS / RHEL 7 – The Geek Diary
5.3. Viewing the Current Status and Settings of firewalld Red Hat Enterprise Linux 7 | Red Hat Customer Portal
Open firewall port on CentOS 7 - Stack Overflow
Package manager
DNF Package Manager For RPM-Based Linux Distributions - LinuxAndUbuntu - Linux News | Apps Reviews | Linux Tutorials HowTo
what is different between DNF and yum [Quick review] - Eldernode
DNF command on CentOS 8 - what is DNF command - DNF tutorial
EPEL: AUR for CentOS
Top 8 YUM ThirdParty Repositories for CentOS and RHEL
Copr
Category:Copr - FedoraProject
Copr Plugin | DNF
Fedora Hosted is Fedora's equivalent of AUR or PPA, it hosts many Copr (Cool Other Package Repo).
FAQs - Fedora Hosted
UserDocs – copr
HowToEnableRepo – copr
sudo dnf copr enable <reponame>
# for remix such as Korora, specify Fedora base
sudo dnf copr enable <reponame> fedora-23-x86_64Fedy
Fedy - Tweak your Fedora
folkswithhats/fedy: Fedy lets you install multimedia codecs and additional software that Fedora doesn't want to ship, like mp3 support, Adobe Flash, Oracle Java etc., and much more with just a few clicks.