Oracle Linux Server Administration Guide

This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.

Where Oracle Linux sits

Oracle Linux is a RHEL-compatible distribution with its own kernels and its own support. dnf, NetworkManager, firewalld, and SELinux are the familiar tools. The kernel may be Oracle's UEK or the RHCK. Those are not the same kernel. Write which one is running, because a driver or a third-party module may care.

It is not RHEL with a different wallpaper, and it is not the installation of Oracle Database. Database software is a separate change with its own backup. Do not install a database because the OS is Oracle's.

Lab hostname edge-01 and address 192.0.2.10/24 via 192.0.2.1 follow the same documentation rule. Named admin, key, firewalld allowing the lab prefix and not the world, SELinux enforcing.

Ksplice or any live-update product is optional and licensed. It is not assumed by this guide, and it does not replace the patch guide's reboot decision unless you actually have it and have tested it.

The first hour on a lab host

Step 1 on Oracle Linux covers identity and kernel. Record the OS version and uname -r, and label UEK or RHCK. The kernel is the fact a module will trip over. The check is: Both strings are in the ticket. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for Oracle Linux draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

Step 2 on Oracle Linux covers admin. Named user and key. Same hardening order. The check is: Key login works. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for Oracle Linux draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

Step 3 on Oracle Linux covers network. nmcli and firewalld for the lab prefix. A database port is not opened in this hour. The check is: SSH from the prefix works. Nothing extra listens. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for Oracle Linux draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

Step 4 on Oracle Linux covers SELinux. Enforcing. A database install later does not get a head start by disabling it now. The check is: getenforce is Enforcing. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for Oracle Linux draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

Step 5 on Oracle Linux covers updates. dnf update from Oracle Linux repos. No database RPM was included by accident. The check is: The package list you accepted has no database server you did not name. If that check fails, stop and fix the ticket before the next step. The way back is the previous file or the previous image, which the provisioning guide told you to keep. Do not install a second package to hide a failed step. The browser generators for Oracle Linux draft a starter. They do not log in. Read the draft, delete what this lab does not need, and replace prompt-for-this. A line that worked on a different distribution is not a reason to paste it here.

# Oracle Linux lab. Review before you paste.
# Record UEK or RHCK: uname -r
# dnf, firewalld, SELinux Enforcing.
# Lab address 192.0.2.10/24 via 192.0.2.1.
# This page does not install a database.
# prompt-for-this is not a password to keep.

The commands you will actually repeat

dnf update from Oracle Linux repositories. Read the list. Know whether a kernel update changes UEK. Reboot unless a live-update product you run has a tested path.

firewall-cmd and nmcli as on the family. getenforce stays Enforcing.

If you add a repository for a database client, that is a separate ticket from the OS update.

Record the kernel package name next to the OS version so the next person does not assume RHCK.

What Oracle Linux is not

Oracle Linux is not a database install.

UEK is not RHCK. Do not follow a kernel-module guide for the wrong one.

It is not Rocky or Alma. Do not point yum or dnf at their mirrors.

The hour you stop

Write the hostname, the role, and the clock time before you change Oracle Linux. If this host is also serving users, it is not the lab and this first hour belongs on a spare. The provisioning guide is how the spare gets built. A change without a spare is a change you can still postpone.

Keep the console or the out-of-band path open for the whole hour. Reloading a network service, a firewall, or a secure-shell daemon from the only session is how a lab becomes a drive across town. The hardware guide names that path for a physical machine. A virtual machine uses the hypervisor console. A cloud instance uses the serial console the platform gives you. Test it before the reload, not after.

The address 192.0.2.10/24 and the gateway 192.0.2.1 are documentation. They belong in the lab note and nowhere else. On a real network, use the prefix the network desk already assigned. On a cloud instance, use the address the platform assigned and do not hard-code the documentation range into user-data. If a generator filled the documentation address into a production draft, delete it.

prompt-for-this is a reminder that a secret is missing. It is not a password you set, not a token you commit, and not a string you leave in a configuration file because the service started. The real secret lives in the password store. The ticket says who can read it. A file that still contains the reminder is a file you have not finished.

One service is enough for the first hour on Oracle Linux. The purpose from the fundamentals page says which service. Every other package stays uninstalled until its own guide has a ticket. A host that enables a web server, a database, and a queue in the first hour has three changes and no proof. Finish the login, the address, and the update. Then stop.

Read the package transaction before you accept it. A count of packages is not a review. If the list contains a repository you did not add, stop. If it contains a kernel, the patch guide's reboot decision applies and the console stays open. If it contains software this role does not need, remove that line from the plan rather than installing it and disabling it later.

The previous image, the previous configuration file, or the previous package version is the rollback. Write the path down while the host still works. A rollback you invent after a failed reload is a guess. The migration guide assumes the old copy is still there. Do not delete it in the same hour to free a disk.

When the checks pass, copy the notes into the ticket and leave the host alone. The next host waits until a second person can repeat the login and the address from the notes. A fleet built from memory drifts. A fleet built from the file the provisioning guide stored stays boring, which is the point of Oracle Linux in production.

If a step on Oracle Linux fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied config produces a host nobody can rebuild. Rebuild from the image instead. The time you lose is smaller than the time you will spend explaining the hybrid.

Hand the finished lab to the guide that matches the role: web, mail, storage, backup, or hardening. Oracle Linux being installed is not the same as the role being ready. The role guide has its own proof. Do not skip it because the package manager exited without an error.

A second person reads the hostname, the address, and the rollback path aloud before you build the next host. If they cannot find those three in the ticket, the notes are not done. Silence is not agreement. The check is the sentence they repeat back.

Store the working notes next to the image version. A month from now Oracle Linux will still boot from that pair, and the chat where you remembered a flag will be gone. The file is the memory. The host is replaceable. That is the whole point of writing this hour down.

Oracle Linux checks before a second host

Confirm this before you call the change done: Oracle Linux is the OS the hostname reports, not a neighbour you copied from. The lab address 192.0.2.10/24 is gone before this host is placed on a real network. prompt-for-this is not the password that was set, and no password is in the ticket. The named admin can log in with a key. The package manager used is the one this page names. A network file from a different distribution was not pasted in. The config test or the apply command for this network tool succeeded. The previous image or install file is kept. No new third-party repository was added in the first hour. A service you do not need was not enabled to see what it does. Console or out-of-band access works before you reload SSH. A second person read the hostname and the address. UEK or RHCK is written next to uname -r. No database server was installed by this page. SELinux is Enforcing. And repositories are Oracle Linux's. If one of those fails, stop.

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