openvpn-auth-azure-ad
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jkroepke
openvpn-auth-azure-ad connects to the OpenVPN management interface and handle the authentication ageist Azure AD.
openvpn-auth-azure-ad
State: Discontinued - Follow up project: https://github.com/jkroepke/openvpn-auth-oauth2
openvpn-auth-azure-ad is an external service connects to the openvpn management interface and handle the authentication of connecting users against Azure AD.
OpenVPN version 2.4 is required. 2.5 is not tested yet.
Tested environment
Python
- Python 3.11
Server
- OpenVPN 2.5.6
Client
Authenticators
Currently, openvpn-auth-azure-ad supports 2 authentication method against Azure AD:
- device authorization grant flow
- Resource Owner Password Credentials grant (not recommend, see docs for limitations)
Additionally, if enabled openvpn-auth-azure-ad supports OpenVPNs auth-token mechanismus to allow users to bypass
then authenticator above on re-authentications, e.g. due reneg-sec.
Installation
via pip
# pip install openvpn-auth-azure-ad
For install pip on your system, see pip docs.
To run a persistent daemon, you copy the systemd unit file to /etc/systemd/system, then
run
# systemctl enable openvpn-auth-azure-ad
# systemctl start openvpn-auth-azure-ad
via docker
https://hub.docker.com/r/jkroepke/openvpn-auth-azure-ad
# docker run --rm \
-v <path of openvpn mgmt socket>:/openvpn/management.sock
-v /etc/openvpn-auth-azure-ad/config.conf:/etc/openvpn-auth-azure-ad/config.conf \
-e AAD_CLIENT_ID= \
-e OPENVPN_AAD_AUTH_SOCKET_PATH=/openvpn/management.sock \
-e OPENVPN_AAD_AUTH_PASSWORD= \
jkroepke/openvpn-auth-azure-ad
Usage
Args that start with '--' (eg. -V) can also be set in a config file (/etc/openvpn-auth-azure-ad/config.conf or ~/.openvpn-auth-azure-ad or specified via -c). Config file syntax allows: key=value, flag=true, stuff=[a,b,c] (for details, see syntax at https://goo.gl/R74nmi). If an arg is specified in more than one place, then commandline values override environment variables which override config file values which override defaults.
usage: openvpn-auth-azure-ad.py [-h] [-c CONFIG] [-V] [-t THREADS] [-a AUTHENTICATORS] [--auth-token] [--auth-token-lifetime AUTH_TOKEN_LIFETIME] [--remember-user] [--webauth] [--webauth-url WEBAUTH_URL]
[--openvpn-identity-key {common_name,username}] [--verify-openvpn-client] [--verify-openvpn-client-id-token-claim] [-H OPENVPN_HOST] [-P OPENVPN_PORT] [-s OPENVPN_SOCKET]
[-p OPENVPN_PASSWORD] [--openvpn-release-hold] --client-id CLIENT_ID [--token-authority TOKEN_AUTHORITY] [--graph-endpoint GRAPH_ENDPOINT] [--prometheus]
[--prometheus-listen-addr PROMETHEUS_LISTEN_ADDR] [--prometheus-listen-port PROMETHEUS_LISTEN_PORT] [--log-level LOG_LEVEL]
options:
-h, --help show this help message and exit
-c CONFIG, --config CONFIG
path of config file [env var: AAD_CONFIG_PATH]
-V, --version show program's version number and exit
-t THREADS, --threads THREADS
Amount of threads to handle authentication [env var: AAD_THREAD_COUNT]
OpenVPN User Authentication:
-a AUTHENTICATORS, --authenticators AUTHENTICATORS
Enable authenticators. Multiple authenticators can be separated with comma [env var: AAD_AUTHENTICATORS]
--auth-token Use auth token to re-authenticate clients [env var: AAD_AUTH_TOKEN]
--auth-token-lifetime AUTH_TOKEN_LIFETIME
Lifetime of auth tokens in seconds [env var: AAD_AUTH_TOKEN_LIFETIME]
--remember-user If user authenticated once, the users refresh token is used to reauthenticate silently if possible. [env var: AAD_REMEMBER_USER]
--webauth Support OpenVPN WebAuth capabilities, if client supports. [env var: AAD_REMEMBER_USER]
--webauth-url WEBAUTH_URL
Wrapper Page for WebAuth capabilities. Copy docs/ folder to host a dedicated one. [env var: AAD_REMEMBER_USER]
--openvpn-identity-key {common_name,username}
Define which value from OpenVPN should be used for identity the AAD user. Supported values: 'common_name', 'username' [env var: AAD_OPENVPN_IDENTITY_KEY]
--verify-openvpn-client
Check if openvpn client common_name matches Azure AD token claim [env var: AAD_VERIFY_OPENVPN_CLIENT]
--verify-openvpn-client-id-token-claim
AAD id_token claim used for client verification [env var: AAD_VERIFY_OPENVPN_CLIENT_ID_TOKEN_CLAIM]
OpenVPN Management Interface settings:
-H OPENVPN_HOST, --openvpn-host OPENVPN_HOST
Host of OpenVPN management interface. [env var: OPENVPN_AAD_AUTH_HOST]
-P OPENVPN_PORT, --openvpn-port OPENVPN_PORT
Port of OpenVPN management interface. [env var: OPENVPN_AAD_AUTH_PORT]
-s OPENVPN_SOCKET, --openvpn-socket OPENVPN_SOCKET
Path of socket or OpenVPN management interface. [env var: OPENVPN_AAD_AUTH_SOCKET_PATH]
-p OPENVPN_PASSWORD, --openvpn-password OPENVPN_PASSWORD
Passwort for OpenVPN management interface. [env var: OPENVPN_AAD_AUTH_PASSWORD]
--openvpn-release-hold
Release hold on OpenVPN Server if --management-hold is enabled [env var: OPENVPN_AAD_AUTH_RELEASE_HOLD]
Azure AD settings:
--client-id CLIENT_ID
Client ID of application. [env var: AAD_CLIENT_ID]
--token-authority TOKEN_AUTHORITY
A URL that identifies a token authority. It should be of the format https://login.microsoftonline.com/your_tenant. By default, we will use
https://login.microsoftonline.com/organizations [env var: AAD_TOKEN_AUTHORITY]
--graph-endpoint GRAPH_ENDPOINT
Endpoint of the graph API. See: https://developer.microsoft.com/en-us/graph/graph-explorer [env var: AAD_GRAPH_ENDPOINT]
Prometheus settings:
--prometheus Enable prometheus statistics [env var: AAD_PROMETHEUS_ENABLED]
--prometheus-listen-addr PROMETHEUS_LISTEN_ADDR
prometheus listen addr [env var: AAD_PROMETHEUS_LISTEN_HOST]
--prometheus-listen-port PROMETHEUS_LISTEN_PORT
prometheus statistics [env var: AAD_PROMETHEUS_PORT]
--log-level LOG_LEVEL
Configure the logging level. [env var: AAD_LOG_LEVEL]
Args that start with '--' (eg. -V) can also be set in a config file (/etc/openvpn-auth-azure-ad/config.conf or ~/.openvpn-auth-azure-ad or specified via -c). Config file syntax allows: key=value, flag=true,
stuff=[a,b,c] (for details, see syntax at https://goo.gl/R74nmi). If an arg is specified in more than one place, then commandline values override environment variables which override config file values which
override defaults.
Register an app with AAD
See: https://docs.microsoft.com/en-us/azure/active-directory/develop/quickstart-register-app
TL;DR
- Login as admin into tenant
- Open App registrations in Azure AD admin center
- Click new registration
- Pick a name, chose a "Supported account types"-option. Let the redirect uri blank and click register.
- Copy the client-id. You need the client-id as configuration option for
openvpn-auth-azure-ad. - Click on Authentication on the left menu
- "Add a platform", pick Mobile and desktop applications and chose the "MSAL only" option.
- On Advanced settings, set "Allow public client flows" to yes.
Required settings on OpenVPN configuration files
server.conf
Use auth-gen-token only on OpenVPN 2.5+. It conflicts with --auth-token.
management socket-name unix [pw-file]
management-hold
management-client-auth
See Reference manual for OpenVPN
for detailed management settings.
If no client certificate are required
If your setup does not require certificates, the following options are required:
username-as-common-name
client.conf
auth-user-pass
auth-retry interact
auth-user-pass is always required otherwise dynamic challenges will not work.
Prometheus support
openvpn-auth-azure-ad has some built-in prometheus support to collect some statistics about authenticators. By default, the prometheus endpoint listen on port 9723.
Related projects
- https://github.com/CyberNinjas/openvpn-auth-aad
- https://github.com/stilljake/openvpn-azure-ad-auth
Copyright and license
© 2022 Jan-Otto Kröpke (jkroepke)
Licensed under the MIT License
jkroepke