dns-update/main.sh
2022-02-11 20:24:15 +01:00

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#!/bin/bash
source variables.conf
KEY="$(pwd)/dns.key"
TTL=604800
FQDN=$(hostname)
MYIP=$(ip route get 8.8.8.8 | grep -oP 'src \K[^ ]+')
MYNUMBER=$(echo $MYIP | cut -d '.' -f 4) # last byte of IP
#MYIP=$(dig +short myip.opendns.com @resolver1.opendns.com)
# if $MYIP is not a valid IP, exit
if [[ ! "$MYIP" =~ ^([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$ ]]; then
echo "Invalid IP, aborting"
exit 1
fi
# fetch current record with dig, and choose what to do
current_ip_record=$(dig $FQDN +short)
if [[ "$current_ip_record" =~ ^([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.([1-9]?[0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$ ]]; then
if [[ ! "$MYIP" = "$current_ip_record" ]]; then
echo "Updating record"
else
echo "Record is already up to date, exiting."
exit 0
fi
else
echo "Server unreachable or no record for $FQDN, exiting."
exit 0
fi
nsupdate -k $KEY -v << EOF
server $NS
zone $MAINZONE
update delete $FQDN. A
update add $FQDN. $TTL A $MYIP
send
EOF
nsupdate -k $KEY -v << EOF
server $NS
zone $REVERSEZONE
update delete $MYNUMBER.$REVERSEZONE PTR
update add $MYNUMBER.$REVERSEZONE $TTL PTR $FQDN.
send
EOF
exit 0