Contents

DNS

Domain name service

Check mail record with dig

   1 dig mx bitarus.allowed.org

Check mail record with dig directly in name server

   1 dig mx bitarus.allowed.org @ns.bitarus.allowed.org

Check reverse dns

   1 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

In bind9 server

   1 # change apparmor in ubuntu 
   2 apt install apparmor-utils
   3 sudo aa-complain /usr/sbin/named
   4 service bind9 restart
   5 
   6 cd /tmp # bind server
   7 dnssec-keygen -a HMAC-SHA512 -b 512 -n USER rpi.dyn.bitarus.allowed.org.
   8 # generates 2 files, one with extension .key and another with extension .private with the same symmetric key
   9 # it generates a symmetric key
  10 # ensures integrity -anti-tampering and authenticity
  11

/etc/bind/keys.conf

secret contains the Key: value in K<...>.private file generated by dnssec-keygen command

   1 key rpi.dyn.bitarus.allowed.org. {
   2     algorithm HMAC-SHA512;
   3     secret "???????";
   4 };

/etc/bind/named.conf

   1 include "/etc/bind/keys.conf";
   2 zone "bitarus.mooo.com" IN {
   3   type master;
   4   file "/etc/bind/bitarus.mooo.com.hosts";
   5   allow-update { key "rpi.dyn.bitarus.allowed.org."; };
   6 };

/etc/bind/bitarus.mooo.com.hosts

Subdomain bitarus.mooo.com

   1 $ORIGIN .
   2 $TTL 604800     ; 1 week
   3 bitarus.mooo.com        IN SOA  bitarus.mooo.com. root.bitarus.mooo.com. (
   4                                 6          ; serial
   5                                 604800     ; refresh (1 week)
   6                                 86400      ; retry (1 day)
   7                                 2419200    ; expire (4 weeks)
   8                                 604800     ; minimum (1 week)
   9                                 )
  10                         NS      bitarus.mooo.com.
  11                         A       54.68.9.58
  12                         MX      5 mail.bitarus.mooo.com.
  13                         TXT     "keyx=valuex"
  14 $ORIGIN bitarus.mooo.com.
  15 labs                    A       54.68.9.58

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

In raspberry pi

   1 cd /tmp
   2 scp  user@bitarus.allowed.org:/tmp/K*dyn* . 
   3 mkdir ~/rpiDdns
   4 mv Kr* ~/rpiDdns/
   5 cd  ~/rpiDdns/
   6 chmod 0400 Krp*
   7 sudo apt update

nsupdate-rpi.sh

   1 logger "Running nsupdate-rpi.sh"
   2 EXT_IP=$(wget -qO- http://ifconfig.co/ip)
   3 KEY="/home/pi/rpiDdns/Krpi.dyn.bitarus.allowed.org.+165+55648.private"
   4 echo "Key: $KEY"
   5 
   6 cat <<EOF | nsupdate -k "$KEY"
   7 server bitarus.allowed.org
   8 zone bitarus.mooo.com
   9 update delete rpi.bitarus.mooo.com. A
  10 update add rpi.bitarus.mooo.com. 600 A $EXT_IP
  11 show
  12 send
  13 EOF

Steps

   1 chmod 755 nsupdate-rpi.sh
   2 crontab -e
   3 */10 * * * * /home/pi/scripts/nsupdate-rpi.sh

chucknorris host

   1 named-checkconf /etc/bind/named.conf
   2 named-checkzone bitarus.mooo.com /etc/bind/bitarus.mooo.com.hosts
   3 service named restart 
   4 ping chucknorris.bitarus.mooo.com

nslookup

   1 nslookup
   2 > server x.example.org
   3 Default server: x.example.org
   4 Address: 1.2.3.4#53
   5 > set type=any
   6 > x.example.com 
   7 Server:         x.example.org
   8 Address:        1.2.3.4#53
   9 
  10 Name:   x.example.com
  11 Address: 1.2.3.4
  12 > exit