#!/bin/bash
#
# base-stack
# https://git.stack-source.com/msb/base-stack
# Copyright (c) 2022 Matthew Saunders Brown <matthewsaundersbrown@gmail.com>
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
#
# this installer expects a clean Ubuntu 20.04 install

# require root
if [ "${EUID}" -ne 0 ]; then
  echo "This script must be run as root"
  exit 1
fi

# do some basic pre-install checks - these are *not* exhaustive
os_id=`lsb_release -is`
os_release=`lsb_release -rs`
if [ $os_id != Ubuntu ] || [ $os_release != 22.04 ]; then
  echo "this installer only runs on Ubuntu 22.04, bailing out"
  exit 1
fi

# set webmaster email address, used below
WEBMASTER=webmaster@`hostname -d`

# have packages automatically start/restart/stop after install/upgrade/uninstall
if [[ -f /usr/sbin/policy-rc.d ]]; then
  sed -i "s|exit 101|exit 0|g" /usr/sbin/policy-rc.d
fi
if [[ -f /etc/needrestart/needrestart.conf ]]; then
  sed -i "s|^#\$nrconf{restart} = 'i';|\$nrconf{restart} = 'a';|g" /etc/needrestart/needrestart.conf
  # disable kernelhints (no warnings about currently running kernel version)
  echo '$nrconf{kernelhints} = 0;' > /etc/needrestart/conf.d/kernelhints.conf
fi

# set system variables
echo "vm.swappiness = 10" >> /etc/sysctl.d/60-swappiness.conf
/sbin/sysctl --quiet --system

# update system
DEBIAN_FRONTEND=noninteractive apt-get -y update
# update grub first, by itself, as it requires special overrides to run unattended
DEBIAN_FRONTEND=noninteractive apt-get -y -o Dpkg::Options::="--force-confdef" -o Dpkg::Options::="--force-confold" install grub-common grub2-common grub-pc grub-pc-bin
DEBIAN_FRONTEND=noninteractive apt-get -y dist-upgrade

# remove unwanted packages
DEBIAN_FRONTEND=noninteractive apt-get -y purge snapd cryptsetup ufw iptables landscape-common popularity-contest
DEBIAN_FRONTEND=noninteractive apt-get -y autoremove
systemctl daemon-reload

# disable motd
sed -i 's|ENABLED=1|ENABLED=0|g' /etc/default/motd-news
chmod 644 /etc/update-motd.d/10-help-text
# disable apt news
/usr/bin/pro config set apt_news=false

# configure unattended upgrades with automatic reboots
DEBIAN_FRONTEND=noninteractive apt-get -y install unattended-upgrades
sed -i 's|^APT::Periodic::Update-Package-Lists.*|APT::Periodic::Update-Package-Lists "1";|g' /etc/apt/apt.conf.d/10periodic
sed -i 's|^APT::Periodic::Download-Upgradeable-Packages.*|APT::Periodic::Download-Upgradeable-Packages "1";|g' /etc/apt/apt.conf.d/10periodic
sed -i 's|^APT::Periodic::AutocleanInterval.*|APT::Periodic::AutocleanInterval "7";|g' /etc/apt/apt.conf.d/10periodic
sed -i 's|^APT::Periodic::Update-Package-Lists.*|APT::Periodic::Update-Package-Lists "1";|g' /etc/apt/apt.conf.d/20auto-upgrades
sed -i 's|^APT::Periodic::Unattended-Upgrade.*|APT::Periodic::Unattended-Upgrade "1";|g' /etc/apt/apt.conf.d/20auto-upgrades
sed -i 's|//     "${distro_id}:${distro_codename}-updates";|       "${distro_id}:${distro_codename}-updates";|g' /etc/apt/apt.conf.d/50unattended-upgrades
sed -i 's|//Unattended-Upgrade::Remove-Unused-Kernel-Packages "true";|Unattended-Upgrade::Remove-Unused-Kernel-Packages "true";|g' /etc/apt/apt.conf.d/50unattended-upgrades
sed -i 's|//Unattended-Upgrade::Remove-Unused-Dependencies "false";|Unattended-Upgrade::Remove-Unused-Dependencies "true";|g' /etc/apt/apt.conf.d/50unattended-upgrades
sed -i 's|//Unattended-Upgrade::Automatic-Reboot "false";|Unattended-Upgrade::Automatic-Reboot "true";|g' /etc/apt/apt.conf.d/50unattended-upgrades
# between 1:00 and 1:55am
REBOOT_TIME=01:$(printf "%02d" $((0 + RANDOM % 55)))
sed -i "s|//Unattended-Upgrade::Automatic-Reboot-Time \"02:00\";|Unattended-Upgrade::Automatic-Reboot-Time \"$REBOOT_TIME\";|g" /etc/apt/apt.conf.d/50unattended-upgrades
sed -i "s|//Unattended-Upgrade::Mail \"\";|Unattended-Upgrade::Mail \"$WEBMASTER\";|g" /etc/apt/apt.conf.d/50unattended-upgrades

# firewalld
# without "--no-install-recommends" ipset and ipables are pulled in, and we don't need or want those
DEBIAN_FRONTEND=noninteractive apt-get -y install firewalld --no-install-recommends
firewall-cmd --set-default-zone=public
# get public interface (e.g. eth0, enp0s10, etc.) then add it to the default (public) zone
INTERFACE=$(ip route get 1.1.1.1 | sed -n 's/.*dev \([^\ ]*\).*/\1/p')
firewall-cmd --permanent --zone=public --add-interface=$INTERFACE
# ssh should already be enabled by default, just making sure
firewall-cmd --permanent --zone=public --add-service=ssh
# default firewalld public zone enables dhcpv6-client, we don't want that
firewall-cmd --permanent --zone=public --remove-service=dhcpv6-client
# blacklist - for local blacklisting
firewall-cmd --permanent --new-ipset=blacklist --type=hash:net
firewall-cmd --permanent --ipset=blacklist --set-short=Blacklist
firewall-cmd --permanent --ipset=blacklist --set-description="Blacklist IP set for creating blacklists local to this server. Use firewall-blacklist-add.sh and firewall-blacklist-rem.sh to add/remove IPs to the blacklist."
firewall-cmd --permanent --zone=drop --add-source=ipset:blacklist
# fail2ban - fail2ban blocking
firewall-cmd --permanent --new-ipset=fail2ban --type=hash:ip --option=timeout=90000
# 90000 timeout is 25 hours. Assumption is that 24 hours is the longest ban that fail2ban will implement, timeout is in place as a backup to remove out of date IPs
firewall-cmd --permanent --ipset=fail2ban --set-short=Fail2Ban
firewall-cmd --permanent --ipset=fail2ban --set-description="IP set for use by fail2ban. IPs in this set get added to the Drop zone."
firewall-cmd --permanent --zone=drop --add-source=ipset:fail2ban
systemctl restart firewalld

# fail2ban
DEBIAN_FRONTEND=noninteractive apt-get -y install fail2ban
chmod 644 fail2ban/*.local
chmod 644 fail2ban/*/*.conf
cp -a fail2ban/* /etc/fail2ban/
echo "destemail = $WEBMASTER" >> /etc/fail2ban/jail.local
echo "bantime = 24h" >> /etc/fail2ban/jail.d/defaults-debian.conf
echo "maxretry = 3" >> /etc/fail2ban/jail.d/defaults-debian.conf
echo "logpath = /var/log/auth.log tail" >> /etc/fail2ban/jail.d/defaults-debian.conf
systemctl enable fail2ban
systemctl start fail2ban

# adjust journald config to prevent /var/log/journal/... from using excessive disk space
sed -i 's|.*SystemMaxUse=.*|SystemMaxUse=1G|g' /etc/systemd/journald.conf
sed -i 's|.*RuntimeMaxUse=.*|RuntimeMaxUse=1G|g' /etc/systemd/journald.conf
sed -i 's|.*SystemMaxFiles=.*|SystemMaxFiles=10|g' /etc/systemd/journald.conf
sed -i 's|.*RuntimeMaxFiles=.*|RuntimeMaxFiles=10|g' /etc/systemd/journald.conf
sed -i 's|.*MaxRetentionSec=.*|MaxRetentionSec=1week|g' /etc/systemd/journald.conf
systemctl restart systemd-journald.service

# install some handy extra packages
DEBIAN_FRONTEND=noninteractive apt-get -y install gdu exa pwgen net-tools

# install
chmod 750 sbin/*
cp sbin/* /usr/local/sbin/

echo ""
echo "Unattended upgrades & fail2ban are configured to send notifications to $WEBMASTER."
echo "Update /etc/apt/apt.conf.d/50unattended-upgrades and /etc/fail2ban/jail.local to suit your needs."