DNS, SPF, and DKIM

This commit is contained in:
Joshua Tauberer 2013-08-21 16:53:22 -04:00
parent e06b4f5ccf
commit 5cef1bb63d
8 changed files with 179 additions and 4 deletions

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@ -41,6 +41,8 @@ Then launch a new instance. We're creating a m1.small instance --- it's the smal
source ec2/start_instance.sh
It will wait until the instance is available.
You'll probably want to associate it with an Elastic IP. If you do, you'll need to update the INSTANCE_IP variable.
Configure the server:

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@ -7,7 +7,8 @@ UBUNTU_CONFIG="us-east-1 13.04 amd64 instance-store"
export AMI=`curl -s http://cloud-images.ubuntu.com/locator/ec2/releasesTable | python3 tools/get_ubuntu_ami.py $UBUNTU_CONFIG`
ec2-create-group -d "mailinabox" "mailinabox"
for PORT in 25 587 993; do ec2-authorize mailinabox -P tcp -p $PORT -s 0.0.0.0/0; done
for PORT in 25 53 587 993; do ec2-authorize mailinabox -P tcp -p $PORT -s 0.0.0.0/0; done
for PORT in 53; do ec2-authorize mailinabox -P udp -p $PORT -s 0.0.0.0/0; done
ec2run $AMI -k $EC2_KEYPAIR_NAME -t m1.small -z $AWS_AZ -g mailinabox > instance.info
export INSTANCE=`cat instance.info | grep INSTANCE | awk {'print $2'}`

45
scripts/dkim.sh Normal file
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@ -0,0 +1,45 @@
# Install OpenDKIM.
#
# After this, you'll still need to run dns_update to get the DKIM
# signature in the DNS zones.
apt-get install -q -y opendkim opendkim-tools
mkdir -p /etc/opendkim;
mkdir -p $STORAGE_ROOT/mail/dkim
echo "127.0.0.1" > /etc/opendkim/TrustedHosts
if grep -q "ExternalIgnoreList" /etc/opendkim.conf; then
true; # already done
else
cat >> /etc/opendkim.conf << EOF;
MinimumKeyBits 1024
ExternalIgnoreList refile:/etc/opendkim/TrustedHosts
InternalHosts refile:/etc/opendkim/TrustedHosts
KeyTable refile:/etc/opendkim/KeyTable
SigningTable refile:/etc/opendkim/SigningTable
Socket inet:8891@localhost
RequireSafeKeys false
EOF
fi
# Create a new DKIM key if we don't have one already.
if [ ! -z "$STORAGE_ROOT/mail/dkim/mail.private" ]; then
# Should we specify -h rsa-sha256?
opendkim-genkey -r -s mail -D $STORAGE_ROOT/mail/dkim
fi
chown -R opendkim:opendkim $STORAGE_ROOT/mail/dkim
chmod go-rwx $STORAGE_ROOT/mail/dkim
# add OpenDKIM as a milter to postfix. Be careful. If we add other milters
# later, it needs to be concatenated on the smtpd_milters line.
tools/editconf.py /etc/postfix/main.cf \
smtpd_milters=inet:127.0.0.1:8891 \
non_smtpd_milters=\$smtpd_milters \
milter_default_action=accept
service opendkim restart
service postfix restart

36
scripts/dns.sh Normal file
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@ -0,0 +1,36 @@
# Configures a DNS server using nsd.
#
# After running this script, you also must run scripts/dns_update.sh,
# and any time a zone file is added/changed/removed. It should be
# run after DKIM is configured, however.
apt-get -qq -y install nsd3
if [ -z "$PUBLIC_HOSTNAME" ]; then
PUBLIC_HOSTNAME=example.org
fi
if [ -z "$PUBLIC_IP" ]; then
# works on EC2 only...
PUBLIC_IP=`wget -q -O- http://instance-data/latest/meta-data/public-ipv4`
fi
sudo mkdir -p /var/run/nsd3
mkdir -p "$STORAGE_ROOT/dns";
# Store our desired IP address (to put in the zone files) for later.
echo $PUBLIC_IP > $STORAGE_ROOT/dns/our_ip
# Create the default zone if it doesn't exist.
if [ ! -f "$STORAGE_ROOT/dns/$PUBLIC_HOSTNAME.txt" ]; then
# can be an empty file, defaults are applied elsewhere
cat > "$STORAGE_ROOT/dns/$PUBLIC_HOSTNAME.txt" << EOF;
EOF
fi
chown -R ubuntu.ubuntu $STORAGE_ROOT/dns
ufw allow domain

89
scripts/dns_update.sh Normal file
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@ -0,0 +1,89 @@
# Create nsd.conf and zone files, and updates the OpenDKIM signing tables.
PUBLIC_IP=`cat $STORAGE_ROOT/dns/our_ip`
# Create the top of nsd.conf.
cat > /etc/nsd3/nsd.conf << EOF;
server:
hide-version: yes
# identify the server (CH TXT ID.SERVER entry).
identity: ""
# The directory for zonefile: files.
zonesdir: "/etc/nsd3/zones"
# ZONES
EOF
# For every zone file in our dns directory, build a proper zone
# file and mention it in nsd.conf. And add information to the
# OpenDKIM signing tables.
mkdir -p /etc/nsd3/zones;
truncate --size 0 /etc/opendkim/KeyTable
truncate --size 0 /etc/opendkim/SigningTable
for fn in $STORAGE_ROOT/dns/*.txt; do
fn2=`basename $fn`
zone=`echo $fn2 | sed "s/.txt\$//"`
# If the zone file exists, increment the serial number.
# TODO: This needs to be done better so that the existing serial number is
# persisted in the storage area.
serial=`date +"%Y%m%d00"`
if [ -f /etc/nsd3/zones/$fn2 ]; then
existing_serial=`grep "serial number" /etc/nsd3/zones/$fn2 | sed "s/; serial number//"`
if [ ! -z "$existing_serial" ]; then
serial=`echo $existing_serial + 1 | bc`
fi
fi
cat > /etc/nsd3/zones/$fn2 << EOF;
\$ORIGIN $zone. ; default zone domain
\$TTL 86400 ; default time to live
@ IN SOA ns1.$zone. domain_contact.$zone. (
$serial ; serial number
28800 ; Refresh
7200 ; Retry
864000 ; Expire
86400 ; Min TTL
)
NS ns1.$zone.
IN A $PUBLIC_IP
MX 10 mail.$zone.
300 TXT "v=spf1 mx -all"
mail IN A $PUBLIC_IP
EOF
# If OpenDKIM is set up, append that information to the zone.
if [ -f "$STORAGE_ROOT/mail/dkim/mail.txt" ]; then
cat "$STORAGE_ROOT/mail/dkim/mail.txt" >> /etc/nsd3/zones/$fn2;
fi
cat >> /etc/nsd3/nsd.conf << EOF;
zone:
name: $zone
zonefile: $fn2
EOF
# OpenDKIM
echo "$zone $zone:mail:$STORAGE_ROOT/mail/dkim/mail.private" >> /etc/opendkim/KeyTable
echo "*@$zone $zone" >> /etc/opendkim/SigningTable
done
# Kick nsd.
service nsd3 rebuild
service nsd3 restart # ensure it is running
# Kick opendkim.
service opendkim restart

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@ -1,3 +1,6 @@
. scripts/system.sh
. scripts/dns.sh
. scripts/mail.sh
. scripts/dkim.sh
. scripts/dns_update.sh

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@ -20,7 +20,6 @@ apt-get install -q -y ntp fail2ban
# Turn on the firewall. First allow incoming SSH, then turn on the firewall. Additional open
# ports will be set up in the scripts that set up those services.
ufw allow ssh
#ufw allow domain
#ufw allow http
#ufw allow https
ufw --force enable

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@ -1,6 +1,6 @@
import smtplib, sys, os
fromaddr = "testuser@testdomain.com"
fromaddr = "testuser@" + os.environ.get("DOMAIN", "testdomain.com")
msg = """From: %s
To: %s
@ -10,7 +10,7 @@ This is a test message.""" % (fromaddr, sys.argv[1])
server = smtplib.SMTP(os.environ["INSTANCE_IP"], 587)
server.set_debuglevel(1)
server.starttls()
server.login("testuser@testdomain.com", "testpw")
server.login(fromaddr, "testpw")
server.sendmail(fromaddr, [sys.argv[1]], msg)
server.quit()