ubt2404srv-dns

Ubuntu server 24.04 Bind 9 DNS Services

v24-12-11

This template contains the configuration files needed to run Bind 9 DNS Services on Ubuntu Server 24.04 LTS.

Template override parameters

File _values-tpl.yaml contains template configuration parameters and their default values:

#
#   _values-tpl.yaml
#
#   cskygen template default values file
#
_tplname: ubt2404srv-dns
_tpldescription: Ubuntu server 24.04 DNS bind9 installation
_tplversion: 24-12-11
#
# Values to override
#
## Machine related configuration values
machine:
  hostname: ubt2404srv-dns
  domainname: cskylab.net
  localadminusername: kos
  localadminpassword: "NoFear21"
  timezone: "UTC"
  networkinterface: enp1s0
  ipaddress: 192.168.82.9
  netmask: 24
  gateway4: 192.168.82.1
  searchdomainnames:
    - cskylab.net
  nameservers:
    - 192.168.82.1
  ## Setup directory where configuration files will be injected
  setupdir: "/etc/csky-setup"
  systemlocale: "C.UTF-8"
  systemkeyboard: "us"

Prerequisites

Physical or virtual machine up and running, with a clean or cloud-init installation of Ubuntu server 24.04.
Package openssh-server must be installed to allow remote ssh connections.

Bind9 configuration files

At least two files must be deployed to configure a DNS Bind9 server: named.conf.local and named.conf.options. (See http://www.zytrax.com/books/dns/)

There are some configuration models for these files that should be followed to deploy DNS Bind9 servers:

DNS Server mode	Config file model
Internal DNS Cache	`tpl_dnscache-named.conf.local`
	`tpl_dnscache-named.conf.local`
DNS Stealth Master	`tpl_dnsmaster-named.conf.local`
	`tpl_dnsmaster-named.conf.local`
DNS Slave	`tpl_dnsslave-named.conf.local`
	`tpl_dnsslave-named.conf.local`

Additionally, if deploying a master server, you must provide forward or reverse zone files with resource records.

Zone type	Config file model
Forward	`tpl_dnszone-db.cskylab.net.dns`
Reverse (CIDR Block)	`tpl_dnszone-db.168.192.in-addr.arpa.dns`
Reverse (Class C Subnet)	`tpl_dnszone-db.xxx.xxx.xxx.in-addr.arpa.dns`

How-to guides

Inject & Deploy configuration

To install and configure the machine, open a terminal from the machine configuration directory in the management repository, and perform the following configuration steps:

1. SSH Authentication and sudoers file

# Run csinject.sh in [ssh-sudoers] execution mode
./csinject.sh -k

NOTE: If IP address has not been previously set in cloud-init or net-config, use -r IPaddress until network configuration files are deployed.

This step injects ssh key and sudoers file into the machine.

Required before other configuration options. Its purpose is to allow automated and passwordless logins by using ssh protocol.

If ssh key has not been injected before, you must provide the password for username {{ .machine.localadminusername }}@{{ .machine.hostname }} twice:

First one to install ssh key (ssh-copy-id).
Second one to deploy the sudoers file.

2. Network configuration

# Run csinject.sh to inject & deploy configuration in [net-config] deploy mode
./csinject.sh -d -m net-config

NOTE: If IP address has not been previously set in cloud-init or net-config, use -r IPaddress until network configuration files are deployed.

This step deploys network configuration files that allow the machine to operate with specific IP address and hostname. Cloud-init configuration will be disabled from the next start.

Reboot is recommended when finished.

3. Install packages, updates and configuration tasks

# Run csinject.sh to inject & deploy configuration in [install] deploy mode
./csinject.sh -d -m install

This step performs:

Package installation
Updates
Configuration files deployment
Configuration tasks

Required to run at least once in order to complete proper configuration. Reboot is recommended when finished.

4. Configuration tasks

# Run csinject.sh to inject & deploy configuration in [config] deploy mode (default)
./csinject.sh -d

When configuration needs to be changed, this mode redeploys all configuration files into the machine, executing again all configuration tasks.

5. Connect and operate

# Run csconnect.sh to establish a ssh session with sudoer (admin) user
./csconnect.sh

To run scripts and operate from inside the machine, establish an ssh connection with administrator (sudoer) user name {{ .machine.localadminusername }}@{{ .machine.hostname }}.

Update DNS configuration

To update DNS configuration or zone files, from the machine configuration directory, inject & deploy configuration in [config] mode executing:

# Run csinject.sh to inject & deploy configuration in [config] deploy mode (default)
./csinject.sh -d

Bind9 service will be restarted and the new zones and configuration files will be loaded.

The status status and version of the zones loaded will be displayed running inside the machine the command:

named-checkconf -zj

This command runs at the end of the deploy process and show zone status with SOA serial version running.

Utilities

Passwords and secrets

Generate passwords and secrets with:

# Screen
echo $(head -c 512 /dev/urandom | LC_ALL=C tr -cd 'a-zA-Z0-9' | head -c 16)
# File (without newline)
printf $(head -c 512 /dev/urandom | LC_ALL=C tr -cd 'a-zA-Z0-9' | head -c 16) > RESTIC-PASS.txt

Change the parameter head -c 16 according with the desired length of the secret.

Reference

Scripts

cs-deploy

Purpose:
  Machine installation and configuration deployment.
  This script is usually called by csinject.sh when executing Inject & Deploy
  operations. Exceptionally, it can also be run manually from inside the machine.
Usage:
  sudo cs-deploy.sh [-m <execution_mode>] [-h] [-q]
Execution modes:
  -m  <execution_mode>  - Valid modes are:
  
      [net-config]      - Network configuration. (Reboot when finished).
      [install]         - Package installation, updates and configuration tasks (Reboot when finished).
      [config]          - Redeploy config files and perform configuration tasks (Default mode).
Options and arguments:  
  -h  Help
  -q  Quiet (Nonstop) execution.
Examples:
  # Deploy configuration in [net-config] mode:
    sudo cs-deploy.sh -m net-config
  # Deploy configuration in [install] mode:
    sudo cs-deploy.sh -m install
  # Deploy configuration in [config] mode:
    sudo cs-deploy.sh -m config

Tasks performed:

${execution_mode}	Tasks	Block / Description
[net-config]		Network configuration
	Deploy /etc/hostname	Configuration file `hostname` must exist in setup directory.
	Deploy /etc/hosts	Configuration file `hosts` must exist in setup directory.
	Deploy /etc/netplan/01-netcfg.yaml	Configuration file `01-netcfg.yaml` must exist in setup directory.
	Disable cloud-init	Flag that signals that cloud-init should not run.
	Change systemd-resolved	Change configuration of file `/etc/resolv.conf`.
	Try Netplan configuration	Execute `netplan try` to test new network configuration.
	Reboot	Reboot with confirmation message.
[install]		Install and update packages
	Update installed packages	Update package repositories, perform `dist-upgrade` and `autoremove`
	Generate locales	Deploy file `locale.gen` if present in setup directory and execute `locale-gen`.
	Install chrony time sync	Chrony time synchronization (https://chrony.tuxfamily.org)
	Install rng-tools	Increase the available entropy for DNSSEC. (https://wiki.archlinux.org/index.php/Rng-tools)
	Install bind9	Installs bind9 package. (https://help.ubuntu.com/community/BIND9ServerHowto)
[install][config]		Deploy config files and execute configuration tasks
	Set timezone	Set time zone from `time_zone` variable.
	Set locale	Set locale from `system_locale` variable.
	Set keyboard	Set keyboard layout from `system_keyboard` variable.
	Deploy sudoers file	Deploy sudoers configuration file `domadminsudo` (Must be present in setup directory).
	UFW firewall configuration	UFW enabled with ssh and bind9 profiles allowed.
	Change local passwords	If file `kos-pass`is present in setup directory. (Template `tpl-kos-pass` provided).
	Deploy ssh authorized_keys	If file `authorized_keys`is present in setup directory. (Template `tpl-authorized_keys` provided).
	Deploy ssh id_rsa keys	If files `id_rsa` and `id_rsa.pub` are present in setup directory. (Templates `tpl-id_rsa*` provided).
	Generate id_rsa	If doesn't exist for root and sudoer user.
	Deploy ca-certificates	If files with name pattern `ca-*.crt` are present.
	Deploy machine certificate	If files with name pattern `hostname.crt` and `hostname.key`are present.
	Deploy crontab files	If files with name pattern `cron-cs-*` are present in setup directory.
	Deploy bind9 configuration files	Files `named.conf.local` and `named.conf.options` must be present in setup directory.
	Deploy DNS zone files	If files with patterns `db.*.dns` are present in setup directory.
	Restart bind9 service	Bind9 restart and zone configuration check `named-checkconf -zj`.
[install]		Reboot after install
	Reboot	Reboot with confirmation message.

cs-inject

Note: This script runs from the "DevOps Computer", opening a terminal from the machine configuration directory in the management repository,.

Purpose:
  Inject & Deploy configuration files into remote machine.
  This script runs from the management (DevOps) computer, copying all configuration
  files to the remote machine, and calling the script 'cs-deploy.sh' to run from
  inside the remote machine if 'deploy' mode [-d] is selected.
Usage:
  ./csinject.sh [-k] [-i] [-d] [-m <deploy_mode>] [-u <sudo_username>] [-r <remote_machine>] [-h] [-q]
Execution modes:
  -k  [ssh-sudoers] - install ssh key and sudoers file into the machine. Required before other actions.
  -i  [inject]      - Inject only. Inject configuration files into the machine for manual deployment.
  -d  [deploy]      - Inject & Deploy configuration. Calls 'cs-deploy.sh' to run from inside the machine.
Options and arguments:  
  -m  <deploy_mode>       - Deploy mode passed to 'cs-deploy.sh'. Valid modes are:
      [net-config]        - Network configuration. (Reboot when finished).
      [install]           - Package installation, updates and configuration tasks (Reboot when finished).
      [config]            - Redeploy config files and perform configuration tasks (Default mode).
  
  -u  <sudo_username>     - Remote administrator (sudoer) user name (Default value).
  -r  <remote_machine>    - Machine hostname or IPAddress (Default value).
  -h  Help
  -q  Quiet (Nonstop) execution.
Examples:
  # Copy ssh key and sudoers file into the machine:
    ./csinject.sh -k
  # Inject & Deploy configuration in [net-config] mode:
    ./csinject.sh -dm net-config
  # Inject & Deploy configuration in [install] mode:
    ./csinject.sh -dm install
  # Inject & Deploy configuration in [config] mode (default):
    ./csinject.sh -d

Tasks performed:

${execution_mode}	Tasks	Block / Description
[ssh-sudoers]		Inject ssh key and sudoers file
	Perform ssh-copy-id	Insert your public key to be authorized in ssh authentication.
	Deploy sudoers file	Deploy sudoers configuration file `domadminsudo` (Must be present in setup directory).

[inject][deploy]		Copy config files and deploy scripts
	Prepare setup directory in remote machine	Remove setup directory if exist and create empty new one with permissions.
	Inject configuration files	SCP configuration files from configuration management into machine setup directory.
	Deploy scripts to `/usr/local/sbin`	Delete old `cs-*.sh` scripts inside `/usr/local/sbin` and copy new ones from setup directory.

[deploy]		Run cs-deploy from inside the machine
	Execute `cs-deploy.sh` inside the machine	Run `cs-deploy.sh` script inside the machine in mode specified by `deploy-mode` variable`.

cs-connect

Note: This script runs from the "DevOps Computer", opening a terminal from the machine configuration directory in the management repository,.

Purpose:
  SSH remote connection.
  Use this script to remote login into the machine and establish a ssh session.
Usage:
  csconnect.sh [-u <sudo_username>] [-r <remote_machine>] [-h]
Options and arguments:  
  -u  <sudo_username>   - Remote user name (Default value).
  -r  <remote_machine>  - Machine hostname or IPAddress (Default value).
  -h  Help
Examples:
  # Connect to the machine with default values
    ./csconnect.sh
  # Connect to IPAddress with specific user
    ./csconnect.sh -u sudo_username -r 192.168.2.99

Tasks performed:

Tasks	Description
Perform ssh connection	Passwordless ssh connection with timeout.

cs-helloworld

Purpose:
  Sequential block script model.
  Use this script as a model or skeleton to write other configuration scripts.
Usage:
  sudo cs-helloworld.sh [-l] [-m <execution_mode>] [-n <name>] [-h] [-q]
Execution modes:
  -l  [list-status]     - List current status.
  -m  <execution_mode>  - Valid modes are:
      [install]         - Install.
      [remove]          - Remove.
      [update]          - Update and reconfigure.
Options and arguments:  
  -n <name>             - Name of the person to report status.
                          (Optional in list-status. Default value) 
  -h  Help
  -q  Quiet (Nonstop) execution.
Examples:
  # Mode "install":
    sudo cs-helloworld.sh -m install
  # Mode "remove":
    sudo cs-helloworld.sh -m remove
  # Mode "list-status":
    sudo cs-helloworld.sh -l
  # Mode "list-status" with special name to report:
    sudo cs-helloworld.sh -l -n Bond

Tasks performed:

${execution_mode}	Tasks	Block / Description
[install]		Install apps and services
	Task 1	Task 1 description as commented in code.
	Task 2	Task 2 description as commented in code.
	Task n	Task n description as commented in code.
[remove]		Remove apps and services
	Task 1	Task 1 description as commented in code.
	Task 2	Task 2 description as commented in code.
	Task n	Task n description as commented in code.
[update][install]		Update and reconfigure apps and services
	Task 1	Task 1 description as commented in code.
	Task 2	Task 2 description as commented in code.
	Task n	Task n description as commented in code.
[list-status][install] [update][remove]		Display status information
	Display hostname and variables	Show hostame and content of variables used in the script
	Display report message	Display report message with "some surprise"

DNS Security guides

DNS Security recomendations can be found at:

https://www.incibe-cert.es/sites/default/files/contenidos/guias/doc/dns_security_guide.pdf

License

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.