DaveQB's Rambles

I have used No-Ip (Maybe 10 years now). It is a Dynamic DNS service like DyDNS etc. It is good but it is limited how many clients you can have much like all others. So I have toyed with setting up something myself as I have a public Linux DNS server to receive the updated IP info. After trying a few methods that had varying success, I concluded that the following was the best method. DOMAIN would equal a domain name you have set aside for this purose.

1. We setup passwordless ssh to the server. Do a search online with your favourite search engine as there is losts of tutorials already published for this.
2. On client side we run every 10mins

   FILE="DOMAIN-ip"
   curl  ifconfig.me/ip -o  "$FILE"  &>/dev/null
   scp  -q "$FILE" dward.name:
   exit 0
   

3. Setup the zone to accept updates by adding the following to your named.conf for bind9:

   allow-update { localhost;};

   Restart bind9
4. On the server side run hourly cronjob or anything to your hearts content:

   PHY="$(cat DOMAIN-ip)"
   TEMP="$(/bin/mktemp)"
   CMDS="$(/bin/mktemp)"
   CUR="$(host -t A DOMAIN localhost |grep DOMAIN|cut -d' ' -f4)"
   if [ ! "$CUR" == "$PHY" ]
   then
           TIME="$(date +%s)"
   	cat > $CMDS <<EOF
   	update delete DOMAIN A
   	update add DOMAIN 1800 A $PHY
   	send
   	EOF
   /usr/bin/nsupdate $CMDS
   rm -f $CMDS
   rm -f $TEMP
   fi
   

Edit anything there to your needs of course.
References: https://www.debian-administration.org/users/JulienV/weblog/4
http://www.shakabuku.org/writing/dyndns.html