Unbound Dynamic Hostname Script

Description

This script dynamically updates Unbound DNS server configurations with hostname-to-IP mappings for both IPv4 and IPv6 addresses. It is particularly useful for environments with devices obtaining IPs via DHCP, ensuring hostnames resolve locally without manual updates.

Features

• Automatically extracts and assigns hostnames to IPv4 and IPv6 addresses.
• Skips link-local IPv6 addresses (fe80::/10) to avoid unnecessary entries.
• Integrates with OPNsense Unbound's template system for persistent configurations.
• Validates and applies configurations using OPNsense's tools.

Requirements

• OPNsense firewall with Unbound DNS configured.
• Root access to the system.
• Bash shell.

Installation

1. Clone the repository:

git clone https://github.com/amnsharif/IPv6_Hostnames.git
cd unbound-dynamic-hostname

2. Copy the script to /usr/local/bin and make it executable:

sudo cp update_unbound_entries.sh /usr/local/bin/
sudo chmod +x /usr/local/bin/update_unbound_entries.sh

3. Run the script to generate the configuration:

sudo bash update_unbound_entries.sh

Automation

To automate the process, add a cron job:

sudo crontab -e

Add the following line:

0 * * * * bash /usr/local/bin/update_unbound_entries.sh

This will run the script hourly.

How It Works

1. Extracts IPv4 and IPv6-to-MAC mappings using arp and ndp commands.

2. Resolves hostnames for each IP address.

3. Filters out link-local (fe80::/10) IPv6 addresses.

4. Writes the hostname-IP mappings into the Unbound template file.

5. Reloads and validates the Unbound configuration.

Examples

Adding a new device: Simply ensure the device is connected to the network and has a valid hostname. Run the script to add it to Unbound DNS.

Skipping specific addresses: The script automatically skips link-local IPv6 addresses.

Troubleshooting

1. Error. Permission Denied: Ensure the script is executable and run as root.

sudo chmod +x /usr/local/bin/update_unbound_entries.sh

2. Invalid Configuration: Check the Unbound configuration:

configctl unbound check

3. No Hostname Found: Verify that the device has a hostname assigned via DHCP.
4. No such file or directory: Create the OPNsense template directory and +TARGETS file manually:

mkdir -p /usr/local/opnsense/service/templates/sampleuser/Unbound
echo "sampleuser_dynamic_hosts.conf:/usr/local/etc/unbound.opnsense.d/sampleuser_dynamic_hosts.conf" > /usr/local/opnsense/service/templates/sampleuser/Unbound/+TARGETS

Contributing

If you find this helpful and would like to contribute, please consider buying me a coffee or visiting my Patreon page