mailinabox/setup/system.sh

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#!/bin/bash
source /etc/mailinabox.conf
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source setup/functions.sh # load our functions
# Basic System Configuration
# -------------------------
# ### Set hostname of the box
# If the hostname is not correctly resolvable sudo can't be used. This will result in
# errors during the install
#
# First set the hostname in the configuration file, then activate the setting
echo "$PRIMARY_HOSTNAME" > /etc/hostname
hostname "$PRIMARY_HOSTNAME"
# ### Fix permissions
# The default Ubuntu Bionic image on Scaleway throws warnings during setup about incorrect
# permissions (group writeable) set on the following directories.
chmod g-w /etc /etc/default /usr
# ### Add swap space to the system
# If the physical memory of the system is below 2GB it is wise to create a
# swap file. This will make the system more resiliant to memory spikes and
# prevent for instance spam filtering from crashing
# We will create a 1G file, this should be a good balance between disk usage
# and buffers for the system. We will only allocate this file if there is more
# than 5GB of disk space available
# The following checks are performed:
# - Check if swap is currently mountend by looking at /proc/swaps
# - Check if the user intents to activate swap on next boot by checking fstab entries.
# - Check if a swapfile already exists
# - Check if the root file system is not btrfs, might be an incompatible version with
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# swapfiles. User should handle it them selves.
# - Check the memory requirements
# - Check available diskspace
# See https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-14-04
# for reference
SWAP_MOUNTED=$(cat /proc/swaps | tail -n+2)
SWAP_IN_FSTAB=$(grep "swap" /etc/fstab || /bin/true)
ROOT_IS_BTRFS=$(grep "\/ .*btrfs" /proc/mounts || /bin/true)
TOTAL_PHYSICAL_MEM=$(head -n 1 /proc/meminfo | awk '{print $2}' || /bin/true)
AVAILABLE_DISK_SPACE=$(df / --output=avail | tail -n 1)
if
[ -z "$SWAP_MOUNTED" ] &&
[ -z "$SWAP_IN_FSTAB" ] &&
[ ! -e /swapfile ] &&
[ -z "$ROOT_IS_BTRFS" ] &&
[ "$TOTAL_PHYSICAL_MEM" -lt 1900000 ] &&
[ "$AVAILABLE_DISK_SPACE" -gt 5242880 ]
then
echo "Adding a swap file to the system..."
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# Allocate and activate the swap file. Allocate in 1KB chunks
# doing it in one go, could fail on low memory systems
dd if=/dev/zero of=/swapfile bs=1024 count=$((1024*1024)) status=none
if [ -e /swapfile ]; then
chmod 600 /swapfile
hide_output mkswap /swapfile
swapon /swapfile
fi
# Check if swap is mounted then activate on boot
if swapon -s | grep -q "\/swapfile"; then
echo "/swapfile none swap sw 0 0" >> /etc/fstab
else
echo "ERROR: Swap allocation failed"
fi
fi
# ### Set log retention policy.
# Set the systemd journal log retention from infinite to 10 days,
# since over time the logs take up a large amount of space.
# (See https://discourse.mailinabox.email/t/journalctl-reclaim-space-on-small-mailinabox/6728/11.)
tools/editconf.py /etc/systemd/journald.conf MaxRetentionSec=10day
# ### Add PPAs.
# We install some non-standard Ubuntu packages maintained by other
# third-party providers. First ensure add-apt-repository is installed.
if [ ! -f /usr/bin/add-apt-repository ]; then
echo "Installing add-apt-repository..."
hide_output apt-get update
apt_install software-properties-common
fi
# Ensure the universe repository is enabled since some of our packages
# come from there and minimal Ubuntu installs may have it turned off.
hide_output add-apt-repository -y universe
# Install the duplicity PPA.
hide_output add-apt-repository -y ppa:duplicity-team/duplicity-release-git
# Stock PHP is now 8.1, but we're transitioning through 8.0 because
# of Nextcloud.
hide_output add-apt-repository --y ppa:ondrej/php
# ### Update Packages
# Update system packages to make sure we have the latest upstream versions
# of things from Ubuntu, as well as the directory of packages provide by the
# PPAs so we can install those packages later.
echo "Updating system packages..."
hide_output apt-get update
apt_get_quiet upgrade
# Old kernels pile up over time and take up a lot of disk space, and because of Mail-in-a-Box
# changes there may be other packages that are no longer needed. Clear out anything apt knows
# is safe to delete.
apt_get_quiet autoremove
# ### Install System Packages
# Install basic utilities.
#
# * unattended-upgrades: Apt tool to install security updates automatically.
# * cron: Runs background processes periodically.
# * ntp: keeps the system time correct
# * fail2ban: scans log files for repeated failed login attempts and blocks the remote IP at the firewall
# * netcat-openbsd: `nc` command line networking tool
# * git: we install some things directly from github
# * sudo: allows privileged users to execute commands as root without being root
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# * coreutils: includes `nproc` tool to report number of processors, mktemp
# * bc: allows us to do math to compute sane defaults
# * openssh-client: provides ssh-keygen
echo "Installing system packages..."
apt_install python3 python3-dev python3-pip python3-setuptools \
netcat-openbsd wget curl git sudo coreutils bc file \
pollinate openssh-client unzip \
unattended-upgrades cron ntp fail2ban rsyslog
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# ### Suppress Upgrade Prompts
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# When Ubuntu 20 comes out, we don't want users to be prompted to upgrade,
# because we don't yet support it.
if [ -f /etc/update-manager/release-upgrades ]; then
tools/editconf.py /etc/update-manager/release-upgrades Prompt=never
rm -f /var/lib/ubuntu-release-upgrader/release-upgrade-available
fi
# ### Set the system timezone
#
# Some systems are missing /etc/timezone, which we cat into the configs for
# Z-Push and ownCloud, so we need to set it to something. Daily cron tasks
# like the system backup are run at a time tied to the system timezone, so
# letting the user choose will help us identify the right time to do those
# things (i.e. late at night in whatever timezone the user actually lives
# in).
#
# However, changing the timezone once it is set seems to confuse fail2ban
# and requires restarting fail2ban (done below in the fail2ban
# section) and syslog (see #328). There might be other issues, and it's
# not likely the user will want to change this, so we only ask on first
# setup.
if [ -z "${NONINTERACTIVE:-}" ]; then
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if [ ! -f /etc/timezone ] || [ -n "${FIRST_TIME_SETUP:-}" ]; then
# If the file is missing or this is the user's first time running
# Mail-in-a-Box setup, run the interactive timezone configuration
# tool.
dpkg-reconfigure tzdata
restart_service rsyslog
fi
else
# This is a non-interactive setup so we can't ask the user.
# If /etc/timezone is missing, set it to UTC.
if [ ! -f /etc/timezone ]; then
echo "Setting timezone to UTC."
echo "Etc/UTC" > /etc/timezone
restart_service rsyslog
fi
fi
# ### Seed /dev/urandom
#
# /dev/urandom is used by various components for generating random bytes for
# encryption keys and passwords:
#
# * TLS private key (see `ssl.sh`, which calls `openssl genrsa`)
# * DNSSEC signing keys (see `dns.sh`)
# * our management server's API key (via Python's os.urandom method)
# * Roundcube's SECRET_KEY (`webmail.sh`)
#
# Why /dev/urandom? It's the same as /dev/random, except that it doesn't wait
# for a constant new stream of entropy. In practice, we only need a little
# entropy at the start to get going. After that, we can safely pull a random
# stream from /dev/urandom and not worry about how much entropy has been
# added to the stream. (http://www.2uo.de/myths-about-urandom/) So we need
# to worry about /dev/urandom being seeded properly (which is also an issue
# for /dev/random), but after that /dev/urandom is superior to /dev/random
# because it's faster and doesn't block indefinitely to wait for hardware
# entropy. Note that `openssl genrsa` even uses `/dev/urandom`, and if it's
# good enough for generating an RSA private key, it's good enough for anything
# else we may need.
#
# Now about that seeding issue....
#
# /dev/urandom is seeded from "the uninitialized contents of the pool buffers when
# the kernel starts, the startup clock time in nanosecond resolution,...and
# entropy saved across boots to a local file" as well as the order of
# execution of concurrent accesses to /dev/urandom. (Heninger et al 2012,
# https://factorable.net/weakkeys12.conference.pdf) But when memory is zeroed,
# the system clock is reset on boot, /etc/init.d/urandom has not yet run, or
# the machine is single CPU or has no concurrent accesses to /dev/urandom prior
# to this point, /dev/urandom may not be seeded well. After this, /dev/urandom
# draws from the same entropy sources as /dev/random, but it doesn't block or
# issue any warnings if no entropy is actually available. (http://www.2uo.de/myths-about-urandom/)
# Entropy might not be readily available because this machine has no user input
# devices (common on servers!) and either no hard disk or not enough IO has
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# occurred yet --- although haveged tries to mitigate this. So there's a good chance
# that accessing /dev/urandom will not be drawing from any hardware entropy and under
# a perfect-storm circumstance where the other seeds are meaningless, /dev/urandom
# may not be seeded at all.
#
# The first thing we'll do is block until we can seed /dev/urandom with enough
# hardware entropy to get going, by drawing from /dev/random. haveged makes this
# less likely to stall for very long.
echo "Initializing system random number generator..."
dd if=/dev/random of=/dev/urandom bs=1 count=32 2> /dev/null
# This is supposedly sufficient. But because we're not sure if hardware entropy
# is really any good on virtualized systems, we'll also seed from Ubuntu's
# pollinate servers:
pollinate -q -r
# Between these two, we really ought to be all set.
Support for rsync+ssh backup target (#678) * Added support for backup to a remote server using rsync * updated web interface to get data from user * added way to list files from server It’s not using the “username” field of the yaml configuration file to minimise the amount of patches needed. So the username is actually sorted within the rsync URL. Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * Added ssh key generation upon installation for root user. Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * Removed stale blank lines, and fixed typo Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * fix backup-location lines, by switching it from id to class * Various web UI fixes - fixed user field being shadowed ; - fixed settings reading comparaison ; - fixed forgotten min-age field. Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * Added SSH Public Key shown on the web interface UI Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * trailing spaces. Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * fixed the extraneous environment Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * Updated key setup - made key lower in bits, but stronger (using -a option), - made ssh-keygen run in background using nohup, - added independent key file, as id_rsa_miab, - added ssh-options to all duplicity calls to use the id_rsa_miab keyfile, - changed path to the public key display Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * added rsync options for ssh identity support Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * removed strict host checking for all backup operations Signed-off-by: Bernard `Guyzmo` Pratz <guyzmo+github@m0g.net> * Remove nohup from ssh-keygen so errors aren't hidden. Also only generate a key if none exists yet * Add trailing slash when checking a remote backup. Also check if we actually can read the remote size * Factorisation of the repeated rsync/ssh options cf https://github.com/mail-in-a-box/mailinabox/pull/678#discussion_r81478919 * Updated message SSH key creation https://github.com/mail-in-a-box/mailinabox/pull/678#discussion_r81478886
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# We need an ssh key to store backups via rsync, if it doesn't exist create one
if [ ! -f /root/.ssh/id_rsa_miab ]; then
echo 'Creating SSH key for backup…'
ssh-keygen -t rsa -b 2048 -a 100 -f /root/.ssh/id_rsa_miab -N '' -q
fi
# ### Package maintenance
#
# Allow apt to install system updates automatically every day.
cat > /etc/apt/apt.conf.d/02periodic <<EOF;
APT::Periodic::MaxAge "7";
APT::Periodic::Update-Package-Lists "1";
APT::Periodic::Unattended-Upgrade "1";
APT::Periodic::Verbose "0";
EOF
# ### Firewall
# Various virtualized environments like Docker and some VPSs don't provide #NODOC
# a kernel that supports iptables. To avoid error-like output in these cases, #NODOC
# we skip this if the user sets DISABLE_FIREWALL=1. #NODOC
if [ -z "${DISABLE_FIREWALL:-}" ]; then
# Install `ufw` which provides a simple firewall configuration.
apt_install ufw
# Allow incoming connections to SSH.
ufw_limit ssh;
# ssh might be running on an alternate port. Use sshd -T to dump sshd's #NODOC
# settings, find the port it is supposedly running on, and open that port #NODOC
# too. #NODOC
SSH_PORT=$(sshd -T 2>/dev/null | grep "^port " | sed "s/port //" | tr '\n' ' ') #NODOC
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if [ -n "$SSH_PORT" ]; then
for $port in $SSH_PORT; do
if [ "$port" != "22" ]; then
echo "Opening alternate SSH port $port." #NODOC
ufw_limit "$port" #NODOC
fi
done
fi
ufw --force enable;
fi #NODOC
# ### Local DNS Service
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# Install a local recursive DNS server --- i.e. for DNS queries made by
# local services running on this machine.
#
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# (This is unrelated to the box's public, non-recursive DNS server that
# answers remote queries about domain names hosted on this box. For that
# see dns.sh.)
#
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# The default systemd-resolved service provides local DNS name resolution. By default it
# is a recursive stub nameserver, which means it simply relays requests to an
# external nameserver, usually provided by your ISP or configured in /etc/systemd/resolved.conf.
#
# This won't work for us for three reasons.
#
# 1) We have higher security goals --- we want DNSSEC to be enforced on all
# DNS queries (some upstream DNS servers do, some don't).
# 2) We will configure postfix to use DANE, which uses DNSSEC to find TLS
# certificates for remote servers. DNSSEC validation *must* be performed
# locally because we can't trust an unencrypted connection to an external
# DNS server.
# 3) DNS-based mail server blacklists (RBLs) typically block large ISP
# DNS servers because they only provide free data to small users. Since
# we use RBLs to block incoming mail from blacklisted IP addresses,
# we have to run our own DNS server. See #1424.
#
# systemd-resolved has a setting to perform local DNSSEC validation on all
# requests (in /etc/systemd/resolved.conf, set DNSSEC=yes), but because it's
# a stub server the main part of a request still goes through an upstream
# DNS server, which won't work for RBLs. So we really need a local recursive
# nameserver.
#
# We'll install `bind9`, which as packaged for Ubuntu, has DNSSEC enabled by default via "dnssec-validation auto".
# We'll have it be bound to 127.0.0.1 so that it does not interfere with
# the public, recursive nameserver `nsd` bound to the public ethernet interfaces.
#
# About the settings:
#
# * Adding -4 to OPTIONS will have `bind9` not listen on IPv6 addresses
# so that we're sure there's no conflict with nsd, our public domain
# name server, on IPV6.
# * The listen-on directive in named.conf.options restricts `bind9` to
# binding to the loopback interface instead of all interfaces.
# * The max-recursion-queries directive increases the maximum number of iterative queries.
# If more queries than specified are sent, bind9 returns SERVFAIL. After flushing the cache during system checks,
# we ran into the limit thus we are increasing it from 75 (default value) to 100.
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apt_install bind9
tools/editconf.py /etc/default/named \
"OPTIONS=\"-u bind -4\""
if ! grep -q "listen-on " /etc/bind/named.conf.options; then
# Add a listen-on directive if it doesn't exist inside the options block.
sed -i "s/^}/\n\tlisten-on { 127.0.0.1; };\n}/" /etc/bind/named.conf.options
fi
if ! grep -q "max-recursion-queries " /etc/bind/named.conf.options; then
# Add a max-recursion-queries directive if it doesn't exist inside the options block.
sed -i "s/^}/\n\tmax-recursion-queries 100;\n}/" /etc/bind/named.conf.options
fi
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# First we'll disable systemd-resolved's management of resolv.conf and its stub server.
# Breaking the symlink to /run/systemd/resolve/stub-resolv.conf means
# systemd-resolved will read it for DNS servers to use. Put in 127.0.0.1,
# which is where bind9 will be running. Obviously don't do this before
# installing bind9 or else apt won't be able to resolve a server to
# download bind9 from.
rm -f /etc/resolv.conf
tools/editconf.py /etc/systemd/resolved.conf DNSStubListener=no
echo "nameserver 127.0.0.1" > /etc/resolv.conf
# Restart the DNS services.
restart_service bind9
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systemctl restart systemd-resolved
# ### Fail2Ban Service
# Configure the Fail2Ban installation to prevent dumb bruce-force attacks against dovecot, postfix, ssh, etc.
rm -f /etc/fail2ban/jail.local # we used to use this file but don't anymore
rm -f /etc/fail2ban/jail.d/defaults-debian.conf # removes default config so we can manage all of fail2ban rules in one config
cat conf/fail2ban/jails.conf \
| sed "s/PUBLIC_IPV6/$PUBLIC_IPV6/g" \
| sed "s/PUBLIC_IP/$PUBLIC_IP/g" \
| sed "s#STORAGE_ROOT#$STORAGE_ROOT#" \
> /etc/fail2ban/jail.d/mailinabox.conf
cp -f conf/fail2ban/filter.d/* /etc/fail2ban/filter.d/
# On first installation, the log files that the jails look at don't all exist.
# e.g., The roundcube error log isn't normally created until someone logs into
# Roundcube for the first time. This causes fail2ban to fail to start. Later
# scripts will ensure the files exist and then fail2ban is given another
# restart at the very end of setup.
restart_service fail2ban
systemctl enable fail2ban