Setting Up the Server

Why a home server

An always-on Linux machine at home is useful immediately, as a backup target for your laptop, and it’s the best practice ground for everything in this course, since you’ll run it entirely by SSH. An old laptop is ideal: it uses little power, it’s quiet, and its battery rides out short power cuts.

Ubuntu Server needs little: the installation tutorial asks for 2 GB of memory and 5 GB of disk or more ¹. Plan on wiring it to the router with Ethernet, and on an external drive for backups (next lesson).

The image

Ubuntu Server is the same Ubuntu without a desktop, installed through a text installer ¹. The 26.04 image is ubuntu-26.04.1-live-server-amd64.iso, and its line in Ubuntu’s SHA256SUMS reads ²:

cc8a95cde20f6ced61a322420de00f10cc3c90ced545daa46cb9c1a117f1d927 *ubuntu-26.04.1-live-server-amd64.iso

Download, verify, and write it to a USB stick exactly as in module 1, then start the old laptop from the stick with its boot menu key (often Escape, F2, F10, or F12) ¹.

Installing

The installer has sensible defaults; for a first server, mostly accept them ¹. Screen by screen:

1. Language and keyboard; take an installer update if offered ¹.
2. Network: with the Ethernet cable in, it sets itself up by DHCP ¹.
3. Proxy and mirror: leave as they are ¹.
4. Storage: “use an entire disk,” and choose the laptop’s internal disk. This erases it; make sure there’s nothing on it you want ¹.
5. Identity: your name, the server’s name (garden-server), a user name, and a password. You’ll need the password for sudo even when you log in by key ³.
6. SSH: a default install has no open ports, so tick Install OpenSSH server, and import your SSH keys from GitHub with your GitHub user name. When you import keys, password logins over SSH are turned off by default ³, which is exactly what module 5 had you do by hand.
7. Snaps: a list of server snaps; skip them for now ³.
8. Wait for it to install and apply security updates, choose Reboot, remove the stick, and log in at the console ^{1 3}.

Reaching it

At the server’s own keyboard, find its address:

me@garden-server:~$ ip -br addr

In your router’s settings, reserve that address for the server’s MAC address (module 5), so it never changes. Then, from the laptop:

me@garden-laptop:~$ ssh me@192.168.1.10

Check the fingerprint against ssh-keygen -l -f /etc/ssh/ssh_host_ed25519_key.pub on the server the first time (module 5); your GitHub key logs you in. Add a short name to the laptop’s ~/.ssh/config:

Host server
    HostName 192.168.1.10
    User me

From now on, ssh server. (To use garden-server.local instead of the address, install Avahi on the server with sudo apt install avahi-daemon ⁴.) Everything below is done over SSH, from the laptop.

Keeping it awake

By default, closing a laptop’s lid makes systemd-logind suspend it ⁵. A server has to stay on. Create /etc/systemd/logind.conf.d/lid.conf with:

[Login]
HandleLidSwitch=ignore
HandleLidSwitchExternalPower=ignore

Files in logind.conf.d add to the main configuration without editing it ⁵; ignore tells logind to do nothing when the lid closes ⁵. Reboot (sudo systemctl reboot), close the lid, and check you can still ssh server.

Time and updates

Check the clock and time zone, so logs and timers line up with your day ⁶:

me@garden-server:~$ timedatectl
me@garden-server:~$ sudo timedatectl set-timezone America/Chicago

Security updates install themselves every day through unattended-upgrades (module 2) ⁷. A desktop can wait for you to restart; a server nobody logs in to needs to restart on its own when an update requires it. Create /etc/apt/apt.conf.d/52unattended-upgrades-local:

Unattended-Upgrade::Automatic-Reboot "true";
Unattended-Upgrade::Automatic-Reboot-Time "04:00";

Automatic-Reboot restarts when an update asks for it, and Automatic-Reboot-Time waits until the given time, rather than restarting at once ⁷. The 52 in the name makes apt read it after the package’s own 50unattended-upgrades, so your settings take effect and survive package updates.

The firewall

As in module 6, allow SSH from your home network before enabling ufw ⁸:

me@garden-server:~$ sudo ufw default deny incoming
me@garden-server:~$ sudo ufw default allow outgoing
me@garden-server:~$ sudo ufw allow from 192.168.1.0/24 to any port 22 proto tcp
me@garden-server:~$ sudo ufw enable
me@garden-server:~$ sudo ufw status verbose

Then, from the laptop, open a new connection with ssh server to prove you can still get in.

Your dotfiles

Your prompt, aliases, update-all, nano and tmux settings, and git settings, in two minutes (Git course, module 7). The server needs its own SSH key for GitHub:

me@garden-server:~$ ssh-keygen -t ed25519 -C "garden-server"
me@garden-server:~$ cat ~/.ssh/id_ed25519.pub

Add that public key to GitHub, then clone and install:

me@garden-server:~$ git clone git@github.com:you/dotfiles.git ~/dotfiles
me@garden-server:~$ ~/dotfiles/install.sh
me@garden-server:~$ git config --global user.name "Your Name"
me@garden-server:~$ git config --global user.email "you@example.com"

Log out and back in, and the server feels like home.

Your turn

So

Ubuntu Server 26.04 LTS runs happily on an old laptop: verify and write the live-server image, install on the whole disk with OpenSSH and your GitHub keys (which turns password logins off), reserve its address, and give it a Host server entry on the laptop. Set HandleLidSwitch=ignore in logind.conf.d, set the time zone with timedatectl, let unattended-upgrades reboot it at 04:00 when needed, turn on ufw with SSH allowed from home, and install your dotfiles. Next, give it a job.