Configuration

Overview

Himmelblau is configured primarily through a single file: /etc/himmelblau/himmelblau.conf. This file controls authentication behavior, domain bindings, environment setup, policy enforcement, and more.

This page also describes required system integration steps, including PAM and NSS configuration.

Config File: `/etc/himmelblau/himmelblau.conf`

To enable authentication, you must configure the domains option in the /etc/himmelblau/himmelblau.conf file. This setting determines which domains are permitted to authenticate to the host. You MUST only specify the primary domain from each tenant. All other configuration options are optional.

Format

The file uses an INI-like syntax with support for [global] and per-domain sections:

[global]
domains = example.com

[example.com]
app_id = 00000000-1111-2222-3333-444444444444

Key Options

Key	Description
`domains`	Comma-separated list of allowed Entra ID domains
`pam_allow_groups`	Group object IDs and user UPNs allowed to authenticate
`enable_hello`	Enables Linux Hello PIN support

Note: Leaving the pam_allow_groups option unset in the /etc/himmelblau/himmelblau.conf file permits all users to authenticate.

Note: On Ubuntu, you should additionally set use_etc_skel to true and configure home_attr and home_alias to match (I recommend using the CN or SPN attributes). These parameters are necessary, otherwise Ubuntu's snaps will fail to execute. These settings are set by default using the Himmelblau project Debian/Ubuntu packages.

[global]
home_attr = CN
home_alias = CN
use_etc_skel = true

Refer to the himmelblau.conf man page for a full list of options.

⚠️Important: To enable hardware-backed security, you must configure TPM support before authenticating or enrolling this device. It is disabled by default. Learn how to configure TPM ».

PAM Configuration

To allow users to authenticate with Azure Entra ID, Himmelblau must be integrated into your system’s PAM (Pluggable Authentication Module) stack. This directs authentication requests to the pam_himmelblau.so module.

Preferred Configuration Methods

Use one of the following automated tools to insert Himmelblau into the appropriate PAM files.

Ubuntu / Debian:

sudo pam-auth-update

Then check the box labeled Azure authentication.

openSUSE / Tumbleweed:

sudo pam-config --add --himmelblau

All systems (manual file editing):

sudo aad-tool configure-pam

This directly modifies PAM config files such as:

/etc/pam.d/common-auth

ℹ️ This tool is safe to use as a starting point, and allows fine-grained control later if needed.

Manual Configuration (Advanced)

If the above tools don’t produce the desired result or you require precise control over module ordering and behavior, you may manually edit your PAM stack.

Guidelines:

Place pam_himmelblau.so after pam_localuser.so
If using Linux Hello or Passwordless, place Himmelblau before pam_unix.so to avoid password prompts
Always include ignore_unknown_user
Ensure pam_deny.so is placed last

Example: `/etc/pam.d/common-auth`

auth        required      pam_env.so
auth        [default=1 ignore=ignore success=ok] pam_localuser.so
auth        sufficient    pam_unix.so nullok try_first_pass
auth        sufficient    pam_himmelblau.so ignore_unknown_user
auth        required      pam_deny.so

💡 For Passwordless login, move pam_himmelblau.so above pam_unix.soin the pam auth stack to avoid fallback password prompts.

Example: `/etc/pam.d/common-account`

account     [default=1 ignore=ignore success=ok] pam_localuser.so
account     sufficient    pam_unix.so
account     sufficient    pam_himmelblau.so ignore_unknown_user
account     required      pam_deny.so

Example: `/etc/pam.d/common-session`

session optional    pam_systemd.so
session required    pam_limits.so
session optional    pam_unix.so try_first_pass
session optional    pam_umask.so 
session optional    pam_himmelblau.so
session optional    pam_env.so

Example: `/etc/pam.d/common-password`

password    sufficient  pam_himmelblau.so ignore_unknown_user
password    optional    pam_gnome_keyring.so use_authtok
password    sufficient  pam_unix.so use_authtok nullok shadow try_first_pass
password    required    pam_deny.so

NSS Configuration

To ensure system tools can resolve Entra ID users and groups:

Edit /etc/nsswitch.conf

Find the passwd and group lines and modify them to include himmelblau, for example:

passwd:     files himmelblau
group:      files himmelblau

Using Multiple Tenants

You can support multiple Azure Entra ID tenants by listing their primary domain names in the global domains key:

[global]
domains = example.com,contoso.com

[example.com]
home_attr = CN

[contoso.com]
app_id = 1111-2222-3333-4444

Only the primary domain need be listed in the domains key. Other domains associated with the same tenant will be configured automatically.

Each domain block may override options like app_id, idmap_range, or shell. Refer to the himmelblau.conf man page for a full list of options.

Disabling Linux Hello PIN

Linux Hello authentication is enabled by default. To disable it:

[global]
enable_hello = false

Debug Logging

Enable debug logs for troubleshooting:

[global]
debug = true

Logs are written to:

journalctl -u himmelblaud -u himmelblaud-tasks