Update public IP with nsupdate on LeBureau DNS zone

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If your server is behind a connection that may change its public IP and your registrar is LeBUreau, here is a way to update automatically the DNS zone.

First, create your nsupdate key file /PATH/TO/YOUR/KEY.key based on information given by Lebureau. Its content should look something like :

key "lebureau_coop_domain_tld" {
    algorithm hmac-sha512;
    secret "A_STRONG_AND_LONG_SECRET";
};

then you create a bash script /opt/nsupdate/nsupdate-dynip :

#!/usr/bin/env bash

ECHO=$(which echo)
NSUPDATE=$(which nsupdate)

# Set the DNS entry you want to update, please notice the final dot.
HOST="sub.domain.tld."

# Set the key provided by your DNS administrator
KEY="/PATH/TO/YOUR/KEY.key"

# Set the DNS server name or IP
SERVER="ns1.lebureau.coop"

# Set the zone to modify, it can be any zone previous key has permissions to modify
ZONE="domain.tld."

# Get your current public IP address
wget --quiet -O NewIP.txt https://ip.yunohost.org
IP=$(cat NewIP.txt)
rm NewIP.txt

# Get the public IP registered in DNS zone
OLDIP=`dig $HOST +short @45.13.107.8`

if [ "$IP" != "$OLDIP" ];
then
    $ECHO "server $SERVER" > /tmp/nsupdate
    $ECHO "debug yes" >> /tmp/nsupdate
    $ECHO "zone $ZONE" >> /tmp/nsupdate
    $ECHO "update delete $HOST" >> /tmp/nsupdate
    $ECHO "update add $HOST 3600 A $IP" >> /tmp/nsupdate
    $ECHO "send" >> /tmp/nsupdate
fi
$NSUPDATE -k ${KEY} -v /tmp/nsupdate >> /var/log/nsupdate-dynip.log 2>&1

Don’t forget to make this file executable : chmod u+x /opt/nsupdate/nsupdate-dynip

then, you add to crontab -e :
*/5 * * * * [ -x /opt/nsupdate/nsupdate-dynip ] && /opt/nsupdate/nsupdate-dynip

based on adocampo work : nsupdate-dynip/nsupdate-dynip at master · adocampo/nsupdate-dynip · GitHub

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