[clug] For dyndns junkies

[Bob Edwards]

On 21/08/17 20:10, Andrew Janke via linux wrote:
> #! /bin/sh
>
> IP=$(wget -O - http://icanhazip.com/ -o /dev/null)
>
>
> So many good things available out there that I am yet to find.  This
> one courtesy of:
>
>    https://github.com/AntonioCS/no-ip.com-bash-updater.git
>
>
> a
>

Of course, you can also run your own dyndns service, as I do as
as sub-domain of my own domain, for multiple devices.

(side-story: turns out that it is cheaper to hire a VPS in a
data-center in Sydney, with a static IPv4 address, than it is to
get a static IPv4 address on NBN...)

In this case, I use an SSH forced-command on my publicly-facing
server to run a script which uses the client IP(v4) address and
nsupdate to update the bind DNS server.

The client just does this (regularly, in a cron job):
ssh -i <some key> -p $PORT $USER@$MY_DYNDNS_SERVICE nsupdate.sh

and the server has this script (called from another script which
does all the SSH sanity checking):

#!/bin/bash
# by Robert (Bob) Edwards, May 2017

MYNAME="my-name.dyn.example.org"
NSKEYFILE="/path/to/a_key.+157+24468.private"
SERVER=1.2.3.4
TTL=300

read IPADDR OUTPORT INPORT <<< $SSH_CLIENT

echo "IP address is $IPADDR"

cat << EOF | nsupdate -k ${NSKEYFILE}
server $SERVER
update add $MYNAME $TTL A $IPADDR
send
quit
EOF

And one more comment: using VPNs means that I don't actually care
that much anymore what my dynamic IP address is.

cheers,

Bob Edwards.