DNSSEC Signing Script Bash

sign-zones.sh

#!/bin/bash

# DNS Zone Updater 5.0

# Set DNS zone records location
location="/etc/bind/"

# Change to DNS server dir
cd $location

# Set Domains
domains=`ls db.*{.com,.net,.me,.dev,.cloud,.space} | cut -c 4-`

echo $domains

# Fetch current date for serial generation
date=`date +%Y%m%d`

for domain in $domains
do
        # Set Control Bools
        dateJump=0
        serialMismatch=0
        hashMissing=0

        # Check if a hash for this domain exists
        if [ -f $location/.hashes/$domain.sha512 ];
        then
                # Check our current hash to see if changes to the zone have taken place
                HASH=`cat $location/.hashes/$domain.sha512`
        else
                hashMissing=1
        fi

        GENHASH=`/usr/bin/sha512sum $location/db.$domain | cut -b 1-128`

        # Grab the current DNS serial
        SERIAL=`/usr/sbin/named-checkzone $domain db.$domain | egrep -ho '[0-9]{10}'`

        # Grab the first 8 numbers of the serial
        dateCheck=`echo $SERIAL | cut -b 1-8`

        if [ ! $dateCheck == $date ];
        then
                newSerial="$date"
                zero="00"

                # Update the DNS serial to have today's date and reset DNS counter to 0
                sed -i 's/'$SERIAL'/'$(($newSerial$zero))'/' db.$domain
                dateJump=1

        else
                if [ $hashMissing == 0 ];
                then

                        # Check if the zone hash is different
                        if [ ! $HASH == $GENHASH ];
                        then
                                serialMismatch=1
                        fi
                fi
        fi

        if [ $dateJump -eq 1 ] || [ $serialMismatch -eq 1 ] || [ $hashMissing -eq 1 ];
        then
                # Increment the current serial
                sed -i 's/'$SERIAL'/'$(($SERIAL+1))'/' db.$domain

                # Sign the updated zone
                /usr/sbin/dnssec-signzone -o $domain -A -N INCREMENT -3 $(head -c 1000 /dev/urandom | sha1sum | cut -b 1-16) -t db.$domain

                # Save new hash
                /usr/bin/sha512sum $location/db.$domain | cut -b 1-128 > $location/.hashes/$domain.sha512
        else
                echo "$domain zone has no changes, moving on"
                # Do nothing, no changes
        fi
    
        # Run a zone check 
        /usr/sbin/named-checkzone $domain db.$domain
        status=$?
        if [ $status -eq 0 ];
        then
                # Good
                echo "$domain OK"
        else
                # Rollback zone updates and alert of failure
                mv $location.backup/db.$domain.backup $location/db.$domain
                echo "$domain zone could not be updated due to errors in the zone"
                echo "[WARN] $domain zone failed to update!"
        fi

        # Create "Known working" backup
        cp $location/db.$domain $location/.backup/db.$domain.backup
done

# Reload DNS
/usr/sbin/rndc reload

Used this script in a production environment for over 2 years and never once had a DNSSEC-related failure due to zones not being re-signed. There is still a lot left to be desired, this script is heavily tailored to the environment I built it inside so assumptions like "all zone files will start with db.$zone" are environment specific and need to be adjusted for your situation. Same with line 12 where it determines how many domains it needs to cycle through.

If this script catches your eyes, I am working on a Ruby-based replacement that will handle a lot more tasks than this.

I decided to release this version of the DNS maintainer script in the hopes that it helps someone who may be struggling with automating zone signing and all the fun that it entails. The script does not automate the key generation process so you will still have to have a working zone already created before this will work.