= dns =
Domain name service


== Check mail record with dig ==
{{{#!highlight sh
dig mx bitarus.allowed.org
}}}

== Check mail record with dig directly in name server ==
{{{#!highlight sh
dig mx bitarus.allowed.org @ns.bitarus.allowed.org
}}}

== Check reverse dns  ==
{{{#!highlight sh
dig -x 54.68.9.58
}}}

== Ask for Reverse DNS for EC2 Elastic IP address ==
 * https://portal.aws.amazon.com/gp/aws/html-forms-controller/contactus/ec2-email-limit-rdns-request

== Dynamic DNS Raspberry pi ==
{{{#!highlight sh
# change apparmor in ubuntu 
apt install apparmor-utils
sudo aa-complain /usr/sbin/named
service bind9 restart

cd /tmp # bind server
dnssec-keygen -a HMAC-SHA512 -b 512 -n USER rpi.dyn.bitarus.allowed.org.

# secret contains the Key: value
# vim /etc/bind/keys.conf
key rpi.dyn.bitarus.allowed.org. {
    algorithm HMAC-SHA512;
    secret "???????";
};

# vim /etc/bind/named.conf
include "/etc/bind/keys.conf";
zone "bitarus.mooo.com" IN {
  type master;
  file "/etc/bind/bitarus.mooo.com.hosts";
  allow-update { key "rpi.dyn.bitarus.allowed.org."; };
};

#vim /etc/bind/bitarus.mooo.com.hosts
$ORIGIN .
$TTL 604800	; 1 week
bitarus.mooo.com	IN SOA	bitarus.mooo.com. root.bitarus.mooo.com. (
				6          ; serial
				604800     ; refresh (1 week)
				86400      ; retry (1 day)
				2419200    ; expire (4 weeks)
				604800     ; minimum (1 week)
				)
			NS	bitarus.mooo.com.
			A	54.68.9.58
			MX	5 mail.bitarus.mooo.com.
$ORIGIN bitarus.mooo.com.
labs			A	54.68.9.58

sudo chgrp bind /etc/bind
sudo chmod g+w /etc/bind
sudo chown -R bind:bind /etc/bind
service bind9 restart

# In raspberry pi
cd /tmp
scp  user@bitarus.allowed.org:/tmp/K*dyn* . 
mkdir ~/rpiDdns
mv Kr* ~/rpiDdns/
cd  ~/rpiDdns/
chmod 0400 Krp*
sudo apt update

#vim nsupdate-rpi.sh
logger "Running nsupdate-rpi.sh"
EXT_IP=$(wget -qO- http://ifconfig.co/ip)
KEY="/home/pi/rpiDdns/Krpi.dyn.bitarus.allowed.org.+165+55648.private"
echo "Key: $KEY"

cat <<EOF | nsupdate -k "$KEY"
server bitarus.allowed.org
zone bitarus.mooo.com
update delete rpi.bitarus.mooo.com. A
update add rpi.bitarus.mooo.com. 600 A $EXT_IP
show
send
EOF

chmod 755 nsupdate-rpi.sh
crontab -e
*/10 * * * * /home/pi/scripts/nsupdate-rpi.sh
}}}