DNS Script Enhancements for BIND

Improving the reliability and security of DNS management scripts is crucial for maintaining robust DNS operations. Below are detailed enhancements to improve script functionality for BIND configurations.

1. Check Input Parameters

Verify that the correct number of arguments are passed to the script:

if [ $# -ne 2 ]; then
    echo "Usage: $0 <zone_name> <zone_file_name>"
    exit 1
fi

2. Robust Directory and File Checks

Ensure the zone directory and file exist before proceeding with the script:

if [ ! -d "$ZONEDIR" ]; then
    echo "Zone directory $ZONEDIR does not exist."
    exit 1
fi
if [ ! -f "$ZONEDIR/$ZONEFILE" ]; then
    echo "Zone file $ZONEFILE does not exist in $ZONEDIR."
    exit 1
fi

3. Improve Serial Number Handling

Handle serial numbers correctly to avoid issues with multiple entries:

SERIAL=$(grep -m 1 -Eo '[0-9]{10}' $ZONEFILE)
if [ -z "$SERIAL" ]; then
    echo "No serial number found in $ZONEFILE."
    exit 1
fi
NEW_SERIAL=$(($SERIAL + 1))
sed -i "s/$SERIAL/$NEW_SERIAL/" $ZONEFILE

4. Safer DNSSEC Signing

Use non-blocking random data for DNSSEC signing:

RANDOM_SALT=$(head -c 1000 /dev/urandom | sha1sum | cut -b 1-16)
/usr/bin/dnssec-signzone -A -3 $RANDOM_SALT -N increment -o $ZONE -t $ZONEFILE

5. Better Error Handling

Capture and handle errors during DNSSEC signing and service reloading:

if ! /usr/bin/dnssec-signzone -A -3 $RANDOM_SALT -N increment -o $ZONE -t $ZONEFILE; then
    echo "Failed to sign the zone file $ZONEFILE."
    exit 1
fi
if ! systemctl reload $DNSSERVICE; then
    echo "Failed to reload $DNSSERVICE."
    exit 1
fi

6. Avoiding Use of Backticks (`)

Switch to a more modern command substitution syntax for better readability and maintenance:

PDIR=$(pwd)

These enhancements aim to make DNS management scripts more robust and maintainable, ensuring effective and secure DNS operations.