NetworkManager                                        
*   LinWin                      
  4/20/20   NetworkManager   https://docs.fedoraproject.org/en-US/Fedora/23/html/Networking_Guide/index.html  
                                           
   
  Home As of Fedora 20, the default networking service is provided by NetworkManager, which is a dynamic network control and configuration daemon 
  Install / Fedora that attempts to keep network devices and connections up and active when they are available. 
  cronjobs The traditional ifcfg type configuration files are still supported.
  Info (inxi)
  Desktops Users do not interact with the NetworkManager system service directly
  dnf Instead, users perform network configuration tasks via graphical and command-line user interface tools. 
  DNS
  firewalld Application or Tool Description                    
  LVM NetworkManager  The default networking daemon  
  LVM2 nmtui  A simple curses-based text user interface (TUI) for NetworkManager  
  N.Neighbor'd nmcli  A command-line tool provided to allow users and scripts to interact with NetworkManager
  NM control-center  A graphical user interface tool provided by the GNOME Shell  
  Wireless nm-connection-editor  A GTK+ 3 application available for certain tasks not yet handled by control-center  
  Services
  Sys Jour To install:  # dnf install NetworkManager
    Status: # systemctl status NetworkManager
    To start: # systemctl start NetworkManager
    To start on boot-up: # systemctl enable NetworkManager to ensure that NetworkManager starts up every time the system boots
   
   
    1.6 NetworkManager and the Network Scripts   https://docs.fedoraproject.org/en-US/Fedora/23/html/Networking_Guide/sec-NetworkManager_and_the_Network_Scripts.html
   
    In previous Red Hat Enterprise Linux releases, the default way to configure networking was using network scripts.
    The term network scripts is commonly used for the script /etc/init.d/network and any other installed scripts it calls.
    The user supplied files are typically viewed as configuration, but can also be interpreted as an amendment to the scripts.
   
    Although NetworkManager provides the default networking service, Red Hat developers have worked hard to ensure that scripts and NetworkManager cooperate with each other.
    Administrators who are used to the scripts can certainly continue to use them. We expect both systems to be able to run in parallel and work well together
     It is expected that most user shell scripts from previous releases will still work.
   
    Running Network Script
   
    Run the script only with the systemctl utility which will clear any existing environment variables and ensure clean execution.
    # systemctl start network ( stop | restart | status | enable )
   
    Do not run any service by calling /etc/init.d/servicename start|stop|restart|status directly. 
    Note that in Red Hat Enterprise Linux 7, NetworkManager is started first, and /etc/init.d/network checks with NetworkManager to avoid tampering with NetworkManager's connections.
    NetworkManager is intended to be the primary application using sysconfig configuration files and /etc/init.d/network is intended to be secondary, playing a fallback role. 
    NetworkManger  is primary
    The network service is secondary
   
    The /etc/init.d/network script is not event-driven, it runs either: 
    1.  manually (by one of the systemctl commands start|stop|restart network),
    2.  on boot and shutdown if the network service is enabled (as a result of the command systemctl enable network). 
    It is a manual process and does not react to events that happen after boot.
    Users can also call the scripts ifup and ifdown manually.
   
   
    Custom Commands and the Network Scripts
    There are ways to perform custom tasks when network connections go up and down, both with the old network scripts and with NetworkManager
    When NetworkManager is enabled, the ifup and ifdown script will ask NetworkManager whether NetworkManager manages the interface in question, which is found from the “DEVICE=” line in the ifcfg file.
    If NetworkManager does manage that device, and the device is not already connected, then ifup will ask NetworkManager to start the connection. 
     If the device is managed by NetworkManager and it is already connected, nothing is done. 
     If the device is not managed by NetworkManager, then the scripts will start the connection using the older, non-NetworkManager mechanisms
    that they have used since the time before NetworkManager existed. 
    If you are calling "ifdown" and the device is managed by NetworkManager, then ifdown will ask NetworkManager to terminate the connection. 
    The scripts dynamically check NetworkManager, so if NetworkManager is not running, the scripts will fall back to the old, pre-NetworkManager script-based mechanisms. 
   
   
    1.7 Network Configuration Using sysconfig Files