Operating System¶
I will use Ubuntu Server LTS 16.04. Ubuntu is widely used operating system, which means it is relatively easy to get help online. It also gives 5 years of security updates for LTS versions, which is important if we want to let the server run unattended for years.
Docker Playground¶
Assuming you have docker installed, a sandbox for playing around is simple.
docker run -it ubuntu:16.04 bash
Docker is more restrictive than realistic for a real server, though. So a virtual machine via QEMU is better.
QEMU Playground¶
First, we fetch an Ubuntu image.
curl -O http://releases.ubuntu.com/16.04.2/ubuntu-16.04.2-server-amd64.img
This is the “installation CD”. Now we install Ubuntu to a base harddisk image of 4GiB.
qemu-img create -f qcow2 ubuntu-base.img 4G
qemu-system-x86_64 -hda ubuntu-base.img -cdrom ubuntu-16.04.2-server-amd64.img -boot d -enable-kvm -m 1G
Enabling KVM makes stuff faster. The default of 128MiB RAM is not enough, so we set RAM to 1GiB.
Go through the installation process. Personally, I use english as a language, but a german timezone and keyboard layout.
We do not want to modify this base image, so we can easily reset it. Then we can play around without remorse. We use qemu-img to create another image based on the stock Ubuntu.
qemu-img create -f qcow2 -b ubuntu-base.img playground.img
Now we can boot into the playground.
Again we use -enable-kvm -m 1G.
qemu-system-x86_64 -hda playground.img -enable-kvm -m 1G
For quick throw-away experiments,
which are not supposed to be permanent,
you can skip the img-create step via -snapshot.
Here qemu will not modify the playground.img.
qemu-system-x86_64 -hda playground.img -enable-kvm -m 1G -snapshot
Headless Server¶
For a more realistic feeling,
we can disable qemu’s virtual display.
Instead, we ssh into the guest system.
Boot it with -nographic and some port forwarding:
qemu-system-x86_64 -hda playground.img -enable-kvm -m 1G -nographic -net user,hostfwd=tcp::7777-:22 -net nic
Now on the host, use ssh to port 7777.
ssh localhost -p 7777
Converting a Desktop Ubuntu¶
With my laptop-to-homeserver conversion, there is a full desktop system running. It might be nice, to access the server directly with a GUI, but a few things are removed nonetheless.
sudo apt remove google-chrome gnucash #...
NetworkManager provides a DNS resolver on port 53.
To disable this,
edit /etc/NetworkManager/NetworkManager.conf
and comment out the dns=dnsmasq line.
Then restart NetworkManager.
Afterwards the port is free and
we could setup our own DNS server.
sudo systemctl restart NetworkManager
Networking¶
My router is responsible for the IP addresses, so the home server must get one by DHCP.
apt install isc-dhcp-server
Afterwards, networking should work. However, qemu only allows TCP and UDP by default, so ping does not work. Instead we try an update.
apt update
Time¶
Our server should stay in sync automatically, so we use NTP. It should be installed by default. Check via:
timedatectl status
SSH¶
We maintain the server via ssh. If you did not select it during installation, do it now.
apt install openssh-server
Trimming¶
Ubuntu is actually too generous in my opinion. This is why I remove a few packages.
apt remove byobu info tcpdump telnet tasksel screen laptop-detect ftp fuse install-info plymouth xauth
This also removes packages like ubuntu-server,
which is ok,
because these are empty and only used to pull in other packages.
Ubuntu Server¶
The desktop Ubuntu was 32bit, although it is a 64bit processor. When I tried to convert the system, I broke apt. Then I installed Ubuntu from scratch.
Another mistake was to enabled home directory encryption.
That is not a good idea,
if you want to login with an ssh public key.
The ssh server cannot access the authorized_keys file,
if it is encrypted.