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OracleLinux9.2Oracle Linux provides a 100% application binary compatible alternative to Red Hat Enterprise Linux and CentOS Linux for both hybrid and multi-cloud environments.Since 2006, Oracle Linux has been completely free to download and use. Source code, binaries and updates are provided free of charge. It is freely redistributable. Free for use in production environments.今回は、最新のOracle Linux9.2(2023年5月リリース)で進めていきます。This time, we will proceed with the latest Oracle Linux 9.1.(May 2023 Release)１．Oracle Linux9.2 DownloadOracle Linux 9.2 installation image (OracleLinux-R9-U2-x86_64-dvd.iso ) can be downloaded from the following sitehttps://www.oracle.com/linux/

1.Install bash completion extension package# dnf -y install bash-completion# reboot2.Disabling SELinuxFirst, disable selinux.　selinux is a feature that improves auditing and security in Linux, but when enabled, it can limit the behavior of services and the contents of the configuration considerably.Therefore, it is basically a case of invalidation in many cases.SELinux operating modesEnforcing : SELinux functionality is enabled and access control is enabledPermissive : SElinux will warn, but no access restrictions will be placeddisabled : Both SElinux function and access control are disabled

1.Setting up a remote connection via SSHSSH is a service for connecting remotely to a server and is basically running immediately after the OS is installed, but the default settings are somewhat insecure.Here we will configure the default settings to increase the security of SSH connections.2.Firewall (Firewalld) settingsIn Oracle, the firewall is firewalld configured by default and enabled during OS installation.To briefly explain "firewalld," when setting communication control policies, communication permission/blocking rules are applied to predefined zones, and these zones are then assigned to each NIC (network adapter).