#!/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 Debian 12 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 != Debian ] || [ $os_release != 12 ]; then
  echo "This installer only runs on Debian 12 (Bookworm), bailing out."
  exit 1
fi

if lsof /var/lib/dpkg/lock-frontend ; then
  echo "Could not get lock /var/lib/dpkg/lock-frontend"
  echo "See output above for info on what is holding the lock."
  echo "What for the command above to complete, then re-run this script."
  exit 1
fi

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

# set system variables
if [[ ! -f /etc/sysctl.d/60-swappiness.conf ]]; then
  echo "vm.swappiness = 1" >> /etc/sysctl.d/60-swappiness.conf
  /sbin/sysctl --quiet --system
fi

# 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
DEBIAN_FRONTEND=noninteractive apt-get -y dist-upgrade

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

# configure unattended upgrades with automatic reboots
DEBIAN_FRONTEND=noninteractive apt-get -y install unattended-upgrades apt-listchanges
sed -i 's|//      "origin=Debian,codename=${distro_codename}-updates";|        "origin=Debian,codename=${distro_codename}-updates";|g' /etc/apt/apt.conf.d/50unattended-upgrades
# sed -i 's|//      "origin=Debian,codename=${distro_codename}-proposed-updates";|        "origin=Debian,codename=${distro_codename}-proposed-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
echo unattended-upgrades unattended-upgrades/enable_auto_updates boolean true | debconf-set-selections
dpkg-reconfigure -f noninteractive unattended-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 "backend = systemd" >> /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

# adjust rsyslogd to log cron to it's own file, and to not include cron or mail in main syslog file
# sed -i 's|^#cron\.\*|cron\.\*|' /etc/rsyslog.d/50-default.conf
# sed -i 's|^\*\.\*;auth,authpriv\.none|\*\.\*;auth,authpriv\.none;mail\.none;cron\.none|' /etc/rsyslog.d/50-default.conf
# systemctl restart rsyslog

# install some handy extra packages
DEBIAN_FRONTEND=noninteractive apt-get -y install curl exa gdu git isoquery net-tools pwgen sudo
# exa is no longer maintained, eza is a fork that I expect/hope Debian will add to the next release

# 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."
echo "NOTE: No mail server has been installed and emails won't send without one. See the README for more info."