Network configuration on both families
Domain 2 covers network configuration and the two families share almost no vocabulary for it. This guide reads the live state on both, finds the file each keeps its configuration in, makes a change that lasts only until reboot and one that persists - on an interface that cannot break anything - and ends with name resolution, which is configured somewhere else again.
Services and Users Guide 20 of 28 Intermediate
- PlatformsUbuntu 26.04 LTS + AlmaLinux 10.2
- Mandatory access controlAppArmor on Ubuntu, SELinux enforcing on Alma
- Firewallufw / nftables 1.1.6
- TimeAbout 24 min
| Server Name | IP Address | OS | Roles | CPU | RAM | HDD |
|---|---|---|---|---|---|---|
| LPLUS-A01 | 192.168.0.73 | Ubuntu 26.04 LTS | Debian-family host - apt, ufw, netplan, AppArmor | 2 Core | 4 GB | 50 GB |
| LPLUS-B01 | 192.168.0.74 | AlmaLinux 10.2 | RPM-family host - dnf, firewalld, NetworkManager, SELinux | 2 Core | 4 GB | 50 GB |
This guide includes
Use this when an address, a route or a DNS server has to change on a machine you reach over the network. This matters because ip addr add works instantly and survives nothing, and because the file that makes it permanent is in a different place, in a different format, under a different service on each family.
- reading addresses, routes and hostname on both families with the same commands
- finding netplan's YAML and the renderer it hands the work to
- finding NetworkManager's connection profile and the keyfile behind it
- making a runtime-only change, and proving the persistent configuration knows nothing of it
- making a persistent one on the RPM family, and reading the file it wrote
Before you start
- accounts-sudo-and-what-a-login-reads
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What each machine has right now
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Where the Debian family writes it down
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Where the RPM family writes it down
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A change that does not survive
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The same idea on the RPM family, made persistent
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Name resolution, configured somewhere else again
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Putting both machines back