mailinabox/setup/network-checks.sh

# Install the 'host', 'sed', and and 'nc' tools. This script is run before
# the rest of the system setup so we may not yet have things installed.
apt_get_quiet install bind9-host sed netcat-openbsd

# Stop if the PRIMARY_HOSTNAME is listed in the Spamhaus Domain Block List.
# The user might have chosen a name that was previously in use by a spammer
# and will not be able to reliably send mail. Do this after any automatic
# choices made above.
if host "$PRIMARY_HOSTNAME.dbl.spamhaus.org" > /dev/null; then
	echo >&2
	echo "The hostname you chose '$PRIMARY_HOSTNAME' is listed in the" >&2
	echo "Spamhaus Domain Block List. See http://www.spamhaus.org/dbl/" >&2
	echo "and http://www.spamhaus.org/query/domain/$PRIMARY_HOSTNAME." >&2
	echo >&2
	echo "You will not be able to send mail using this domain name, so" >&2
	echo "setup cannot continue." >&2
	echo >&2
	exit 1
fi

# Stop if the IPv4 address is listed in the ZEN Spamhouse Block List.
# The user might have ended up on an IP address that was previously in use
# by a spammer, or the user may be deploying on a residential network. We
# will not be able to reliably send mail in these cases.
# Adapted from: https://github.com/tdulcet/Remote-Servers-Status/blob/master/status.sh
REVERSED_IPV4=$(echo "$PUBLIC_IP" | awk -F'.' '{for(i=NF;i>0;i--) printf "%s%s",$i,(i==1?"\n":".")}')
if host "$REVERSED_IPV4.zen.spamhaus.org" > /dev/null; then
	output=$(dig +short txt "$REVERSED_IPV4.zen.spamhaus.org" 2>&1) && [[ -n "$output" ]] && mapfile -t reasons < <(echo "$output" | grep -v '^;')
	echo >&2
	echo "The IP address $PUBLIC_IP is listed in the Spamhaus Block List." >&2
	if [[ -n "$reasons" ]]; then
		echo "Reason: ${reasons[*]}" >&2
	fi
	echo "See http://www.spamhaus.org/query/ip/$PUBLIC_IP." >&2
	echo >&2
	echo "You will not be able to send mail using this machine, so setup" >&2
	echo "cannot continue." >&2
	echo >&2
	echo "Associate a different IP address with this machine if possible." >&2
	echo "Many residential network IP addresses are listed, so Mail-in-a-Box" >&2
	echo "typically cannot be used on a residential Internet connection." >&2
	echo >&2
	exit 1
fi

# Stop if the IPv6 address is listed in the ZEN Spamhouse Block List.
# Adapted from: https://github.com/tdulcet/Remote-Servers-Status/blob/master/status.sh
if [ -n "$PUBLIC_IPV6" ]; then
	# Expand and reverse IPv6 address, adapted from: https://gist.github.com/lsowen/4447d916fd19cbb7fce4
	REVERSED_IPV6=$(echo "$PUBLIC_IPV6" | awk -F: 'BEGIN{OFS="";}{addCount = 9 - NF; for(i=1;i<=NF;i++) {if(length($i) == 0) {for(j=1;j<=addCount;j++) {$i = ($i "0000");}} else{$i = substr(("0000" $i), length($i)+5-4);}}; print}' | awk -F '' 'BEGIN{OFS=".";}{for(i=NF;i>0;i--) printf "%s%s",$i,(i==1?"\n":".")}')
	if host "$REVERSED_IPV6.zen.spamhaus.org" > /dev/null; then
		output=$(dig +short txt "$REVERSED_IPV6.zen.spamhaus.org" 2>&1) && [[ -n "$output" ]] && mapfile -t reasons < <(echo "$output" | grep -v '^;')
		echo >&2
		echo "The IP address $PUBLIC_IPV6 is listed in the Spamhaus Block List." >&2
		if [[ -n "$reasons" ]]; then
			echo "Reason: ${reasons[*]}" >&2
		fi
		echo "See http://www.spamhaus.org/query/ip/$PUBLIC_IPV6." >&2
		echo >&2
		echo "You will not be able to send mail using this machine, so setup" >&2
		echo "cannot continue." >&2
		echo >&2
		echo "Associate a different IP address with this machine if possible." >&2
		echo "Many residential network IP addresses are listed, so Mail-in-a-Box" >&2
		echo "typically cannot be used on a residential Internet connection." >&2
		echo >&2
		exit 1
	fi
fi

# Stop if we cannot make an outbound connection on port 25. Many residential
# networks block outbound port 25 to prevent their network from sending spam.
# See if we can reach one of Google's MTAs with a 5-second timeout.
if ! nc -z -w5 aspmx.l.google.com 25; then
	echo
	echo "Outbound mail (port 25) seems to be blocked by your network."
	echo
	echo "You will not be able to send mail using this machine, so setup"
	echo "cannot continue."
	echo
	echo "Many residential networks block port 25 to prevent hijacked"
	echo "machines from being able to send spam. I just tried to connect"
	echo "to Google's mail server on port 25 but the connection did not"
	echo "succeed."
	echo
	exit 1
fi