join-domain-formula

This project uses a SaltStack formula to automate the joining of a Windows or Linux system to an Active Directory (or compatible) domain.

This formula has been tested against Windows Server 2012/2016 and Enterprise Linux 6/7 derivatives (Red Hat, CentOS, Scientific Linux, etc.)

This formula uses data externalized via the SaltStack "Pillar" feature. See the sections below for the data required to be present within the supporting pillar.

join-domain windows

join-domain:
  lookup:
    # Required Settings
    dns_name:
    netbios_name:
    username:

    # Mutually Exclusive Required Settings
    encrypted_password:
    key:
    # or
    password:

    # Optional Settings
    oupath:
    admin_users:
    admin_groups:
    ec2config:
    register_primary_connection_address:
    use_suffix_when_registering:
    tries:

Generating key and encrypted_password for Windows

For Windows systems, to generate the key and the encrypted_password pillar parameters, use the code snippet below:

$String = 'Super secure password'
$StringBytes = [System.Text.UnicodeEncoding]::Unicode.GetBytes($String)
$AesObject = New-Object System.Security.Cryptography.AesCryptoServiceProvider
$AesObject.IV = New-Object Byte[]($AesObject.IV.Length)
$AesObject.GenerateKey()
$KeyBase64 = [System.Convert]::ToBase64String($AesObject.Key)
$EncryptedStringBytes = ($AesObject.CreateEncryptor()).TransformFinalBlock($StringBytes, 0, $StringBytes.Length)
$EncryptedStringBase64 = [System.Convert]::ToBase64String($EncryptedStringBytes)
# Save KeyBase64 in pillar as `key`
"key = $KeyBase64"
# Save EncryptedStringBase64 in pillar as `encrypted_password`
"encrypted_password = $EncryptedStringBase64"

After generating the encrypted password, verify its reversibility by using the code snippet below:

$AesObject = New-Object System.Security.Cryptography.AesCryptoServiceProvider
$AesObject.IV = New-Object Byte[]($AesObject.IV.Length)
$AesObject.Key = [System.Convert]::FromBase64String($KeyBase64)
$EncryptedStringBytes = [System.Convert]::FromBase64String($EncryptedStringBase64)
$UnencryptedString = [System.Text.UnicodeEncoding]::Unicode.GetString(($AesObject.CreateDecryptor()).TransformFinalBlock($EncryptedStringBytes, 0, $EncryptedStringBytes.Length))
"unencrypted_password = $UnencryptedString"

Output of verification should display:

unecrypted_password = Super secure password

Permissions required to join AD Domain

The following are the permissions required for the service account used to join computer clients to the AD domain:

See also:

• (requires RedHat account) https://access.redhat.com/solutions/5444941

join-domain:linux

The following parameters are used to join a Linux client to Active Directory. See the pillar.example file for pillar-data structuring.

Information used to join host to target AD domain

Set of parameters used for joining a AD-client to its domain:

• dns_name: The fully-qualified DNS name for the AD domain (e.g., 'aws.lab')

• ad_site_name: (OPTIONAL) The logical name of an Active Directory Sites and Services site to query for domain-controllers. This is used primarily for the 'openldap-client' connector-option

• netbios_name: The "short" or NETBIOS name for the AD domain (e.g., 'AWSLAB')

• username: The account name used to perform automated joins of clients to the AD domain (e.g., 'svc_domjoin_aws'). It is recommended to create a service account that has the bare-minimum permissions necessary to (re)join a client to an AD domain.

• oupath: (OPTIONAL) where in the AD-hierarchy to create the computer account. Leave blank if joining to the default OU or provide the "/"-delimited path to the OU the computer account will be housed within.

• encrypted_password: This is an encrypted representation of the join_svc_acct service account's password. Use openssl's aes-256-cbc encryption option to create the encrypted-string.

• key: The string passed to openssl to encrypt/decrypt the join_svc_acct service account's password.

Information used configure domain-joined client's behvior

• admin_users: (OPTIONAL) List of users to add to the sudoers system
• admin_groups: (OPTIONAL) List of groups to add to the sudoers system
• login_users: (OPTIONAL) List of users to add to SSH daemon's AllowUsers list. Note: all admin_users are automatically included in this list.
• login_groups: (OPTIONAL) List of groups to add to SSH daemon's AllowGroups list. Note: (OPTIONAL)all admin_groups are automatically included in this list.
• trusted_domains: (OPTIONAL) List of domains (within a multi-domin forest) to trust

Tool used for joining client to AD domain

There are a number of third-party and native options available for joining Linux clients to AD domains. This parameter is used to tell the formula which client-behavior should be used. Expected valid values will be 'centrify', 'pbis', 'quest', 'sssd' and 'winbind'. As of this version of the formula, 'pbis' and 'sssd' are supported (though use of 'pbis' is now HIGHLY discouraged due to its discontinuation in late 2019).

• ad_connector: (e.g., 'sssd')

Settings for the URI path-elements to the PBIS installer

These two values are used to determine where to locate the AD-client's installer software. HTTP is the expected (read "tested") download method. Other download methods may also work (but have not been tested).

• connector_rpms: Top-level search-key for PBIS-related elements. Remaining keys in this block are sub-keys of this key.
• pbis-open: URL of the pbis-open RPM
• pbis-open-devel: URL of the pbis-open-devel RPM (rarely used)
• pbis-open-gui: URL of the pbis-open-gui RPM (rarely used)
• pbis-open-legacy: URL of the pbis-open-legacy RPM (infrequently used)
• pbis-open-upgrade: URL of the pbis-open-upgrade RPM

Directories where (the PBIS) AD-client utilities are installed to the system

List of directories associated with the chosen ad_connector software/method.

• install_bin_dir: Primary installation-directory for the connector-software (e.g., /opt/pbis)

• install_var_dir: Primary directory for var-style connector-software files (e.g. /var/lib/pbis)

• install_db_dir: Primary directory hosting connector-software's cache-databases (e.g., /var/lib/pbis/db)

SSSD-specific pillar settings

SSSD configuration parameters for domain-specific .conf files under the /etc/sssd/conf.d/ directory can be provided using the following pillar dictionary parameter:

• sssd_conf_parameters:

  sssd_conf_parameters:
  <key1>: '<value1>'
  ...
  <keyN>: '<valueN>'

Any parameter supported by sssd may be used within sssd_conf_parameters to customize the operation of sssd.

List of RPMs to look for

This is a list of RPMs associated with the AD client. For some client-types (PBIS is known to require this), the formula will evaluate the presence/version of these RPMs to help determine whether the requested install should be performed as a new install or an upgrade (where possible).

• connectorRpms:

  • RPM1
  • RPM2
  • ...
  • RPMn

List of critical files to look for

This is a list of critical files - typically configuration files - that the formula will look for to help determine whether the requested install should be performed as a new install or an upgrade (where possible). This is only known to be required for the PBIS integration.

• checkFiles:

  • CFG1
  • CFG2
  • ...
  • CFGn

Generating key and encrypted_password for Linux

The Linux portions of the join-domain-formula make use of a reversible, AES 256-bit ECB-encrypted string to store password data with a Salt pillar. To create the reversible, crypted string, you need three things:

• The openssl tools
• The password of the domain-join account
• A semi-random string to use as the lock/unlock key for the encrypted string.

The lock/unlock key can be either manually or automatically generated. A good method for automatically generating the key is to execute something similar to (< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c${1:-10};echo ). This might give you an output similar to F_6ln9jV3X

Once the domain-join account's password and the lock/unlock key are available, use openssl's enc functionality to generate the reversible crypt-sting via a method similar to the following.

$ echo 'MyP@ssw*rd5tr1ng' | \
  openssl enc -aes-256-cbc -md sha256 -a -e -salt -pass pass:'F_6ln9jV3X'
U2FsdGVkX19pOx6FMnowkQ9vVGmHPuL5xWFwY5+EnB7Wy4rYze5HDmSZoTitwZDO

After generating the crypt-string, verify its reversibility by doing something similar to the following:

echo 'U2FsdGVkX19pOx6FMnowkQ9vVGmHPuL5xWFwY5+EnB7Wy4rYze5HDmSZoTitwZDO' | \
  openssl enc -aes-256-cbc -md sha256 -a -d -salt -pass pass:'F_6ln9jV3X'
MyP@ssw*rd5tr1ng

After verification, place the crypt-string and its lock/unlock string into the appropriate Pillar fields.