Chapter 5 Post-Installation Configuration

This chapter describes system configuration changes that you might be required to make after an installation.

5.1 Registering With the Unbreakable Linux Network

After you install Oracle Linux 8 on a system, you have the option to register the system with the Unbreakable Linux Network (ULN), provided you have an account. To register the system, visit To obtain Oracle Linux updates from ULN, you must have an Oracle Linux support subscription.

You can also register with ULN by using the uln_register shell command. To use the Oracle Linux 8 GNOME desktop menu, select Activities and then search for ULN Registration. Click the ULN Registration shortcut icon to start the graphical registration wizard.

For more information about ULN, see Oracle® Linux 8: Managing Software on Oracle Linux.

During the ULN registration, your server is automatically registered with the Oracle Linux 8 BaseOS Latest and Oracle Linux 8 Application Stream Packages repositories. ULN also provides channels for Oracle-specific software packages such as Ksplice and other software that is available to Oracle Premier Support customers. To enable access to these packages, log in to ULN and subscribe your system to the Oracle Software for Oracle Linux 8 channel.

If you have an Oracle Linux Premier Support account, you can opt to use Ksplice, which enables you to keep your systems secure and highly available by automatically updating them with the latest kernel security errata and other critical updates. If you choose to use Ksplice, you can subscribe your systems to the Ksplice for Oracle Linux channel and install Ksplice packages on them. After completing the registration, use the dnf command to install the Ksplice Uptrack package. The Ksplice Uptrack client downloads the access key from ULN and automatically configures itself so that your system can immediately begin to use Ksplice Uptrack. For more information, see Oracle® Linux: Ksplice User's Guide

5.2 Obtaining Errata and Updates From the Oracle Linux Yum Server

Oracle also provides all errata and updates for Oracle Linux through the Oracle Linux yum server, which includes updates to the base distribution, but does not include Oracle-specific software. You do not require an Oracle Linux support subscription to use this service. For more information about obtaining updates from the Oracle Linux yum server, go to

By default, all new installations of Oracle Linux 8 are automatically configured to use the Oracle Linux yum server. If you subsequently register the system with ULN, any configuration for using the Oracle Linux yum server is automatically disabled.

The following entries in the /etc/yum.repos.d/oracle-linux-ol8.repo file enable you to download the latest available packages for Oracle Linux 8 and Unbreakable Enterprise Kernel Release 6:

name=Oracle Linux $releasever BaseOS ($basearch)

name=Oracle Linux $releasever Application Stream ($basearch)


5.3 Obtaining Packages From the Oracle Linux Installation Media

After installation, follow these steps to configure dnf to use the full installation ISO image as a repository for installing packages:

  1. Mount the full installation ISO image on a suitable mount point, such as /mnt:

    $ sudo mount -t iso9660 -o loop full_image.iso /mnt
  2. Create the file /etc/yum.repos.d/Media.repo that contains entries similar to the following:

    name=Oracle Linux 8 Base Media
    name=Oracle Linux 8 AppStream Media

    If RPM-GPG-KEY-oracle is not in the default location on the system as shown in the example, then specify full path accordingly.

  3. Use the dnf repolist command to check the repository configuration.

5.4 Applying Updates

After you have set up the ULN channels, Oracle Linux yum server repositories, or the installation media repositories that yum should use, update all of the installed packages:

$ sudo dnf update

This command upgrades your system to the latest available update of Oracle Linux 8.

Use the following command to install or update a specific package:

$ sudo dnf update package

For more information, see the dnf(8) man page.

5.5 Managing an Oracle Linux System After an Installation

The following are some common tasks for managing an Oracle Linux system after an installation:

System Locale and Keyboard Layout

Use the localectl command to change the default system locale and keyboard layout, or you can edit the settings in the /etc/locale.conf file, and then reboot the system. For more information, see the localectl(1) and locale.conf(5) man pages.

System Date and Time

Use the timedatectl command to change the system date and time. For more information, see the timedatectl(1) man page.

System Services

Use the systemctl command to enable, start and stop system services. For more information, see the systemctl(1) man page.

System Firewall

To implement a simple, general-purpose firewall, you can use the Firewall Configuration GUI (firewall-config) or the firewall-cmd command to create basic packet filtering rules. Many services are pre-defined so that you can add rules for entire services, without needing to know which ports to enable. For example, to enable HTTP access to your system, you could run:

$ sudo firewall-cmd --permanent --zone=public --add-service=http

To see a listing of pre-defined services, run:

$ sudo firewall-cmd --get-services

If a service that you require is not already defined, or you are using a non-standard port for the service, you could specify a port manually, for example:

$ sudo firewall-cmd --permanent --zone=public --add-port=3890/tcp

For more information about the firewalld service, see

To create a more complex firewall configuration, use the nft command to configure the nftables framework rules for IPv4 and IPv6 directly. See the nft(8) man page for details.

System State

Use the systemctl command to change the run state of the system. See the systemctl(1) man page for details.

Change the default system state and switch to the multi-user graphical environment (run level 5 in previous Oracle Linux releases) as follows:

$ sudo systemctl set-default
$ sudo systemctl isolate

Change the default system state and switch to the multi-user command-line environment (run level 3 in previous Oracle Linux releases) as follows:

$ sudo systemctl set-default
$ sudo systemctl isolate

Reboot the system:

$ sudo systemctl reboot

Shut down and power off the system by running the following command:

$ sudo systemctl poweroff