OVH: Custom Installation

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Introduction

I have been running my own dedicated server for about 20 years now. I started running FreeBSD servers, had a couple OpenBSD servers even, but some time around early 2013 I made the switch to using Arch Linux. Have I gone mad? Possibly, but that's not relevant. Some might say Arch Linux does not belong on a server, or in a production environment. Nonsense! Any Linux distribution, properly setup, can be run as a server in a production environment. I use Arch on my desktop and on my laptop and honestly the setup on my servers does not diff too much from those installations aside from a little redundancy. I apply the same security principles and practices to both.

For the creation of this guide I used my server with OVH's subsidiary So you Start (SYS). The process is the same for OVH and Kimsufi (aside from the Manager being a bit different), I have had servers with all three.

Installation

First in order to install Arch Linux from scratch we need to get the server net-booted into the Rescue Mode.

Rescue Mode

Enter the Control Panel and reboot the machine into Rescue Mode. There should be either a button on the right called "Rescue" or "Netboot".

OVH will email you the root password for rescue mode ssh login, make sure your spam filter did not catch it.

Once the machine has been restarted into rescue mode and login information has been obtained, login over ssh. These additional command line options here will make it so it does not record the hostkey (given that this is about to change once Arch is installed).

# ssh -oUserKnownHostsFile=/dev/null -oStrictHostKeyChecking=no root@X.X.X.X

WARNING: The moment you login change the root password with passwd, OVH emails passwords in plain-text which is susceptible to MITM attacks.

Take note of the Debian environment.

Disk Setup

For most of the mid to higher tier servers you get two hard drives. Using RAID-10 (far 2 layout), which prioritizes read speed, availability and redundancy will be optimal."Linux software RAID: why you should always use RAID 10 instead of RAID 1". //blog.a2o.si/2014/09/07/linux-software-raid-why-you-should-always-use-raid-10-instead-of-raid-1/.  Since there is only the two drives, write speeds should be on par with RAID1. LVM can then be used on top of RAID for partition management.
Pull up a list of all of the disks in the system.

# lsblk

If the server was previously installed in a non-RAID setup, it should be mounted inside of /mnt. If so, un-mount the partition.

# unmount /mnt/sdX1

Wipe the current disks so there is no interference.

# dd if=/dev/zero of=/dev/sdX bs=1M count=2048

If there was a RAID volume previously on the drives, a reboot may be required.

Wipe the current partition scheme and create a new partition table. Do this for both drives.

# echo -e "o\nn\np\n1\n\n\na\nw" | fdisk /dev/sdX

Create the RAID10 array and add the disks.

# mdadm --create /dev/md0 --level=10 --layout=f2 --raid-devices=2 /dev/sd[ab]1

It will take a long time to synchronize the array. Check the status with watch -n .1 cat /proc/mdstat Synchronization is transparent to the file-system, continue installing and reboot if needed.

When synchronization is finished, feel free to check to see if any blocks were marked bad.

# cat /sys/block/md0/md/mismatch_cnt

Create the LVM physical volume and put the raid array inside, then verify it was added.

# pvcreate /dev/md0 # pvdisplay

Format the root filesystem.

# mkfs.ext4 /dev/vdX1

Be sure to select Y to overwrite the current partition.

Now that the disk is setup, remove the directory OVH created in /mnt and mount the partition.

# rmdir /mnt/vdX1 # mount /dev/vdX1 /mnt

Bootstrap

At this point download the arch-bootstrap.sh script that was created by Arch Linux user tokland. Then give the script the proper permissions.

# wget https://raw.githubusercontent.com/tokland/arch-bootstrap/master/arch-bootstrap.sh # chmod +x arch-bootstrap.sh

GitHub: tokland/arch-bootstrap

Then bootstrap the system.

# ./arch-bootstrap.sh /mnt

As explained at the completion of the bootstrap script, next mount the system partitions. Don't forget the last one added here.

# mount -t proc proc /mnt/proc/ # mount -t sysfs sys /mnt/sys/ # mount -o bind /dev /mnt/dev/

Also install the haveged package, this is used to accelerate entropy generation.

# wget -O /mnt/tmp/haveged.tar.xz https://www.archlinux.org/packages/extra/x86_64/haveged/download/

Chroot

Chroot into the new install.

# chroot /mnt

Extract and run haveged.

# tar xJf /tmp/haveged.tar.xz # haveged -w 1024

Initialize and populate the Arch Linux pacman keys.

# pacman-key --init # pacman-key --populate archlinux

Finally re-base the system by running pacman to install Arch Linux.

# pacman -S base base-devel arch-install-scripts git grub-bios openssh sudo vim

Generate an fstab file.

# genfstab / > /etc/fstab

Edit the fstab and add the UUID of the disk, to do so use :r !blkid -s UUID -o value /dev/vdX1.

# lsblk # vim /etc/fstab

Boot Loader

Use the scripts that come with grub in order to install the boot loader.

# grub-install /dev/vdX

Open up the grub config in vim and add in the kernel options we saw from the OVH install to GRUB_CMDLINE_LINUX_DEFAULT.

# vim /etc/default/grub

GRUB_CMDLINE_LINUX_DEFAULT="console=tty0 console=ttyS0,115200 quiet"

Generate the GRUB config.

# grub-mkconfig -o /boot/grub/grub.cfg

Networking

Next create a system service to start up the network.

# vim /etc/systemd/network/eth0-dhcp.network

[Match] Name=eth0 en* [Network] DHCP=yes [DHCP] UseMTU=true

Then enable systemd-networkd so that the service is started on boot, also enable the ssh service.

# systemctl enable systemd-networkd # systemctl enable sshd

Edit the sshd config file to enable public key authentication and disable root login.

# vim /etc/ssh/sshd_config

PermitRootLogin no PubkeyAuthentication yes

System Settings

Choose a unique hostname for the machine.

# echo "chaos.kyau.net" > /etc/hostname

Set the proper timezone and generate /etc/adjtime. Check the /usr/share/zoneinfo directory for a list of existing zones.

My VPS is in the BHS datacenter so I will use the timezone that applies.

# ln -sf /usr/share/zoneinfo/America/Montreal /etc/localtime

Choose the proper localization and uncomment it from /etc/locale.gen, the defacto English (US) standard is en_US.UTF-8 UTF-8, and then generate the needed localization.
Also add the localization to /etc/locale.conf.

# sed -i 's/^#en_US.UTF-8 UTF-8/en_US.UTF-8 UTF-8/' /etc/locale.gen # locale-gen # echo "LANG=en_US.UTF-8" > /etc/locale.conf

Set a root password.

# passwd

Create a user account adding it to the wheel group, then give it a password.

# useradd -m -G wheel,systemd-journal -s /bin/bash kyau # passwd kyau

Make sure the wheel group has sudo access.

# sed -i 's/^# %wheel ALL=(ALL) ALL$/%wheel ALL=(ALL) ALL/' /etc/sudoers

Reboot

Exit out of the chroot environment.

# exit

Navigate back to the Web UI for the OVH VPS and click on the button on the right labeled "Reboot my VPS", this will pull the server back out of rescue mode.

Post-Installation

Once the machine has rebooted and you can see a green light on PING and SSH in the OVH dashboard, ssh back into your machine.

# ssh user@ovh.vps.com

Network Time Protocol

As it is always a good idea to keep the systems date/time in sync, for this use systemd-timesyncd.

# sudo timedatectl set-ntp true

Packages

To find the fastest recently updated mirrors for pacman, install the reflector package.

# sudo pacman -S reflector

Reflector will search through the last 100 updated mirrors that use HTTPS and sort them by download speed and then output the list to /etc/pacman.d/mirrorlist overwriting the current list. This command might take a few minutes depending on internet connection speed and latency.

# sudo reflector --latest 100 --protocol https --sort rate --save /etc/pacman.d/mirrorlist

Enable colored output in pacman.

# sudo sed -i 's/#Color/Color/' /etc/pacman.conf

To install aur:pacaur first manually install cower.

# git clone https://aur.archlinux.org/cower.git # cd cower && makepkg -si && cd .. && rm -rf cower

If makepkg complains about GPG keys see this pinned comment or use gpg --recv-keys --keyserver hkp://pgp.mit.edu 1EB2638FF56C0C53

Then proceed to install pacaur manually.

# git clone https://aur.archlinux.org/pacaur.git # cd pacaur && makepkg -si && cd .. && rm -rf pacaur

Perform a full system update.

# pacaur -Syu

See also: Managing Packages