Install OMV4 on debian9

after install debian9, switch to root

apt update
apt upgrade
apt install apt-transport-https git net-tools curl vim

ps, you can add following line to /etc/ssh/sshd_config to allow remote root login

 PermitRootLogin yes

add this to /etc/apt/sources.list

deb https://packages.openmediavault.org/public arrakis main

then

export LANG=C
export DEBIAN_FRONTEND=noninteractive
export APT_LISTCHANGES_FRONTEND=none
apt-get update
apt-get --allow-unauthenticated install openmediavault-keyring postfix
apt-get update
apt-get --yes --auto-remove --show-upgraded --allow-unauthenticated \
    --allow-downgrades --allow-change-held-packages \
    --no-install-recommends \
    --option Dpkg::Options::="--force-confdef" \
    --option DPkg::Options::="--force-confold" \
    install openmediavault

Initialize the system and database. The initial name and password is admin
and openmediavault

omv-initsystem

extra plugins

wget http://omv-extras.org/openmediavault-omvextrasorg_latest_all4.deb
dpkg -i openmediavault-omvextrasorg_latest_all4.deb