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@corny
Last active February 5, 2023 01:52
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Update script for dynv6.com to set your IPv4 address and IPv6 prefix
#!/bin/sh -e
hostname=$1
device=$2
file=$HOME/.dynv6.addr6
[ -e $file ] && old=`cat $file`
if [ -z "$hostname" -o -z "$token" ]; then
echo "Usage: token=<your-authentication-token> [netmask=64] $0 your-name.dynv6.net [device]"
exit 1
fi
if [ -z "$netmask" ]; then
netmask=128
fi
if [ -n "$device" ]; then
device="dev $device"
fi
address=$(ip -6 addr list scope global $device | grep -v " fd" | sed -n 's/.*inet6 \([0-9a-f:]\+\).*/\1/p' | head -n 1)
if [ -e /usr/bin/curl ]; then
bin="curl -fsS"
elif [ -e /usr/bin/wget ]; then
bin="wget -O-"
else
echo "neither curl nor wget found"
exit 1
fi
if [ -z "$address" ]; then
echo "no IPv6 address found"
exit 1
fi
# address with netmask
current=$address/$netmask
if [ "$old" = "$current" ]; then
echo "IPv6 address unchanged"
exit
fi
# send addresses to dynv6
$bin "http://dynv6.com/api/update?hostname=$hostname&ipv6=$current&token=$token"
$bin "http://ipv4.dynv6.com/api/update?hostname=$hostname&ipv4=auto&token=$token"
# save current address
echo $current > $file
@andi34
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andi34 commented Nov 29, 2021

@tolshao nope, works fine. Typo on your end? api64 vs api6?

@tm-107
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tm-107 commented Feb 16, 2022

I don't like caching the "old" IP in a file because if it was changed manually on dynv6.com or the update went wrong, the script doesn't notice.
So this variant works very well for me:

#!/bin/sh

HOSTNAME_DYNV6="****.dynv6.net"
TOKEN_DYNV6="****"

IP4ADDR=$(curl -s http://ipecho.net/plain)
IP6ADDR=`ip addr show eth0 | grep 'scope global dynamic' | grep -Po 'inet6 \K[0-9a-fA-F:]+'`

if [ "$IP4ADDR" = "" ]
then
        echo "Error: unable to determine IPv4 address" 1>&2
fi

if [ "$IP6ADDR" = "" ]
then
        echo "Error: unable to determine IPv6 address" 1>&2
fi

if [ "$IP4ADDR" != "" ]
then
	ping $HOSTNAME_DYNV6 -4 -c 1 > null # a little dirty - needed to update dns-cache
	IP4ADDR_DYNV6=$(dig $HOSTNAME_DYNV6 A +short)

	if [ "$IP4ADDR" != "$IP4ADDR_DYNV6" ]
	then
		echo "IPv4 adress has changed -> update ..."
		curl -s "https://ipv4.dynv6.com/api/update?hostname=$HOSTNAME_DYNV6&token=$TOKEN_DYNV6&ipv4=auto"
		echo "---"
	fi
fi

if [ "$IP6ADDR" != "" ]
then
        ping $HOSTNAME_DYNV6 -6 -c 1 > null # a little dirty - needed to update dns-cache
		IP6ADDR_DYNV6=$(dig $HOSTNAME_DYNV6 AAAA +short)

	if [ "$IP6ADDR" != "$IP6ADDR_DYNV6" ]
	then
		echo "IPv6 adress has changed -> update ..."
		curl -s "https://ipv6.dynv6.com/api/update?hostname=$HOSTNAME_DYNV6&token=$TOKEN_DYNV6&ipv6prefix=auto"
		echo "---"
	fi
fi

@vinnymac
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vinnymac commented May 31, 2022

@tm-107 thanks for the script. While this did most of the work for me, I had to modify it to the following for it to work for my needs. For some reason auto was setting the IPV6 address to one that ended in :: and was missing the last three characters of my address. I made some small modifications to use the current address, including the netmask.

#!/bin/sh

HOSTNAME_DYNV6="****.dynv6.net"
TOKEN_DYNV6="****"
DEVICE_INTERFACE=eno1

IP4ADDR=$(curl -s http://ipecho.net/plain)
IP6ADDR_WITH_MASK=`ip -6 addr list scope global dynamic $DEVICE_INTERFACE | grep -Po 'inet6 \K[0-9a-fA-F:\/]+' | head -n1 | tr -d '\n'`
IP6ADDR=`echo $IP6ADDR_WITH_MASK | tr '/' '\n' | head -n1`

if [ "$IP4ADDR" = "" ]
then
        echo "Error: unable to determine IPv4 address" 1>&2
fi

if [ "$IP6ADDR" = "" ]
then
        echo "Error: unable to determine IPv6 address" 1>&2
fi

if [ "$IP4ADDR" != "" ]
then
	ping $HOSTNAME_DYNV6 -4 -c 1 > null # a little dirty - needed to update dns-cache
	IP4ADDR_DYNV6=$(dig $HOSTNAME_DYNV6 A +short)

	if [ "$IP4ADDR" != "$IP4ADDR_DYNV6" ]
	then
		echo "IPv4 adress has changed -> update ..."
		curl -s "https://ipv4.dynv6.com/api/update?hostname=$HOSTNAME_DYNV6&token=$TOKEN_DYNV6&ipv4=auto"
		echo "---"
	fi
fi

if [ "$IP6ADDR" != "" ]
then
        ping $HOSTNAME_DYNV6 -6 -c 1 > null # a little dirty - needed to update dns-cache
		IP6ADDR_DYNV6=$(dig $HOSTNAME_DYNV6 AAAA +short)

	if [ "$IP6ADDR" != "$IP6ADDR_DYNV6" ]
	then
		echo "IPv6 adress has changed -> update ..."
		curl -s "https://ipv6.dynv6.com/api/update?hostname=$HOSTNAME_DYNV6&token=$TOKEN_DYNV6&ipv6prefix=$IP6ADDR_WITH_MASK"
		echo "---"
	fi
fi

@tolshao and @andi34
curl https://api6.ipify.org will actually return an IPV4 address, but only if you have disabled IPV6. I imagine that was what happened above.

@slyfunky
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I made a simple batch file script for my Windows need, hope it can help someone too.

https://github.com/slyfunky/Pango/blob/main/DNS.bat

@andredasilvapinto
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You should use https

@nilsbentlage
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Made my shell script like this. Think it's leightweight and easy to read

#!/bin/bash

# dynDNS with dynV6 & ipv6 done right

# Initial values

newIpV6=$(ip -6 addr show scope global | grep inet6 | sed -e 's/^.*inet6 \([^ ]*\)\/.*$/\1/;t;d')
oldIpV6='No data in cachefile'

# Change these parameters as you want to

logfile=~/dynv6.log
cachefile=~/.dynv6cache
token=<your-token>
zone=<your-zone>

if [[ -f $cachefile ]]; then
    oldIpV6=$(cat $cachefile)
fi

if [[ $newIpV6 != $oldIpV6 ]]; then
    echo "$(date): Updating the DNS. Output can be found in ${logfile}"
    echo "$(date): $(curl -k "https://dynv6.com/api/update?token=${token}&zone=${zone}&ipv6=${newIpV6}")" | tee -a $logfile
    echo $newIpV6 > $cachefile
else
    echo "$(date): IP did not Change. Skipping the update" | tee -a $logfile
fi

Use this as a cron job as often as you need and you should be good to go.

@HandisableL
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Made my shell script like this. Think it's leightweight and easy to read

#!/bin/bash

# dynDNS with dynV6 & ipv6 done right

# Initial values

newIpV6=$(ip -6 addr show scope global | grep inet6 | sed -e 's/^.*inet6 \([^ ]*\)\/.*$/\1/;t;d')
oldIpV6='No data in cachefile'

# Change these parameters as you want to

logfile=~/dynv6.log
cachefile=~/.dynv6cache
token=<your-token>
zone=<your-zone>

if [[ -f $cachefile ]]; then
    oldIpV6=$(cat $cachefile)
fi

if [[ $newIpV6 != $oldIpV6 ]]; then
    echo "$(date): Updating the DNS. Output can be found in ${logfile}"
    echo "$(date): $(curl -k "https://dynv6.com/api/update?token=${token}&zone=${zone}&ipv6=${newIpV6}")" | tee -a $logfile
    echo $newIpV6 > $cachefile
else
    echo "$(date): IP did not Change. Skipping the update" | tee -a $logfile
fi

Use this as a cron job as often as you need and you should be good to go.

I test it on my RPI4b,Which
ip -6 addr show scope global | grep inet6 | sed -e 's/^.inet6 ([^ ])/.*$/\1/;t;d'
will output two AAAA addr,and this script output error like this:
curl: (3) URL using bad/illegal format or missing URL
Sun 05 Feb 2023 09:45:55 AM CST:

can be fix by adding | head -n 1)

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