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zulip/docs/production/authentication-methods.md

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Authentication methods

Zulip supports a wide variety of authentication methods. Some of them require configuration to set up.

To configure or disable authentication methods on your Zulip server, edit the AUTHENTICATION_BACKENDS setting in /etc/zulip/settings.py, as well as any additional configuration your chosen authentication methods require; then restart the Zulip server.

Details on each method below.

Email and password

The EmailAuthBackend method is the one method enabled by default, and it requires no additional configuration.

Users set a password with the Zulip server, and log in with their email and password.

When first setting up your Zulip server, this method must be used for creating the initial realm and user. You can disable it after that.

Plug-and-play SSO (Google, GitHub, GitLab)

With just a few lines of configuration, your Zulip server can authenticate users with any of several single-sign-on (SSO) authentication providers:

  • Google accounts, with GoogleAuthBackend
  • GitHub accounts, with GitHubAuthBackend
  • GitLab accounts, with GitLabAuthBackend
  • Microsoft Azure Active Directory, with AzureADAuthBackend

Each of these requires one to a handful of lines of configuration in settings.py, as well as a secret in zulip-secrets.conf. Details are documented in your settings.py.

SAML

Zulip 2.1 and later supports SAML authentication, used by Okta, OneLogin, and many other IdPs (identity providers). You can configure it as follows:

  1. These instructions assume you have an installed Zulip server; if you're using Zulip Cloud, see this article, which also has IdP-side configuration advice for common IdPs.

    You can have created a Zulip organization already using the default EmailAuthBackend, or plan to create the organization using SAML authentication.

  2. Tell your IdP how to find your Zulip server:

    • SP Entity ID: https://yourzulipdomain.example.com.

      The Entity ID should match the value of SOCIAL_AUTH_SAML_SP_ENTITY_ID computed in the Zulip settings. You can get the correct value by running the following: /home/zulip/deployments/current/scripts/get-django-setting SOCIAL_AUTH_SAML_SP_ENTITY_ID.

    • SSO URL: https://yourzulipdomain.example.com/complete/saml/. This is the "SAML ACS url" in SAML terminology.

      If you're hosting multiple organizations, you need to use SOCIAL_AUTH_SUBDOMAIN. For example, if SOCIAL_AUTH_SUBDOMAIN="auth" and EXTERNAL_HOST=zulip.example.com, this should be https://auth.zulip.example.com/complete/saml/.

  3. Tell Zulip how to connect to your SAML provider(s) by filling out the section of /etc/zulip/settings.py on your Zulip server with the heading "SAML Authentication".

    • You will need to update SOCIAL_AUTH_SAML_ORG_INFO with your organization name (displayname may appear in the IdP's authentication flow; name won't be displayed to humans).
    • Fill out SOCIAL_AUTH_SAML_ENABLED_IDPS with data provided by your identity provider. You may find the python-social-auth SAML docs helpful. You'll need to obtain several values from your IdP's metadata and enter them on the right-hand side of this Python dictionary:
      1. Set the outer idp_name key to be an identifier for your IdP, e.g. testshib or okta. This field appears in URLs for parts of your Zulip server's SAML authentication flow.
      2. The IdP should provide the url and entity_id values.
      3. Save the x509cert value to a file; you'll use it in the instructions below.
      4. The values needed in the attr_ fields are often configurable in your IdP's interface when setting up SAML authentication (referred to as "Attribute Statements" with Okta, or "Attribute Mapping" with GSuite). You'll want to connect these so that Zulip gets the email address (used as a unique user ID) and name for the user.
      5. The display_name and display_icon fields are used to display the login/registration buttons for the IdP.

  4. Install the certificate(s) required for SAML authentication. You will definitely need the public certificate of your IdP. Some IdP providers also support the Zulip server (Service Provider) having a certificate used for encryption and signing. We detail these steps as optional below, because they aren't required for basic setup, and some IdPs like Okta don't fully support Service Provider certificates. You should install them as follows:

    1. On your Zulip server, mkdir -p /etc/zulip/saml/idps/
    2. Put the IDP public certificate in /etc/zulip/saml/idps/{idp_name}.crt
    3. (Optional) Put the Zulip server public certificate in /etc/zulip/saml/zulip-cert.crt
    4. (Optional) Put the Zulip server private key in /etc/zulip/saml/zulip-private-key.key
    5. Set the proper permissions on these files and directories:
    chown -R zulip.zulip /etc/zulip/saml/
find /etc/zulip/saml/ -type f -exec chmod 644 -- {} +
chmod 640 /etc/zulip/saml/zulip-private-key.key

  5. (Optional) If you configured the optional public and private server certificates above, you can enable the additional setting "authnRequestsSigned": True in SOCIAL_AUTH_SAML_SECURITY_CONFIG to have the SAMLRequests the server will be issuing to the IdP signed using those certificates. Additionally, if the IdP supports it, you can upload the public certificate to enable encryption of assertions in the SAMLResponses the IdP will send about authenticated users.

  6. Enable the zproject.backends.SAMLAuthBackend auth backend, in AUTHENTICATION_BACKENDS in /etc/zulip/settings.py.

  7. Restart the Zulip server to ensure your settings changes take effect. The Zulip login page should now have a button for SAML authentication that you can use to log in or create an account (including when creating a new organization).

  8. If the configuration was successful, the server's metadata can be found at https://yourzulipdomain.example.com/saml/metadata.xml. You can use this for verifying your configuration or provide it to your IdP.

IdP-initiated SSO

The above configuration is sufficient for Service Provider initialized SSO, i.e. you can visit the Zulip webapp and click "Sign in with {IdP}" and it'll correctly start the authentication flow. If you are not hosting multiple organizations, with Zulip 3.0+, the above configuration is also sufficient for Identity Provider initiated SSO, i.e. clicking a "Sign in to Zulip" button on the IdP's website can correctly authenticate the user to Zulip.

If you're hosting multiple organizations and thus using the SOCIAL_AUTH_SUBDOMAIN setting, you'll need to configure a custom RelayState in your IdP of the form {"subdomain": "yourzuliporganization"} to let Zulip know which organization to authenticate the user to when they visit your SSO URL from the IdP. (If the organization is on the root domain, use the empty string: {"subdomain": ""}.).

.. _ldap:

Restricting access to specific organizations

If you're hosting multiple Zulip organizations, you can restrict which organizations can use a given IdP by setting limit_to_subdomains. For example, limit_to_subdomains = ["", "engineering"] would restrict an IdP the root domain and the engineering subdomain.

You can achieve the same goal with a SAML attribute; just declare which attribute using attr_org_membership in the IdP configuration. For the root subdomain, www in the list will work, or any other of settings.ROOT_SUBDOMAIN_ALIASES.

For example, with attr_org_membership set to member, a user with the following attribute in their AttributeStatement will have access to the root and engineering subdomains:

<saml2:Attribute Name="member" NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:unspecified">
  <saml2:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="xs:string">
    www
  </saml2:AttributeValue>
  <saml2:AttributeValue xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="xs:string">
    engineering
  </saml2:AttributeValue>
</saml2:Attribute>

LDAP (including Active Directory)

Zulip supports retrieving information about users via LDAP, and optionally using LDAP as an authentication mechanism.

In either configuration, you will need to do the following:

  1. These instructions assume you have an installed Zulip server and are logged into a shell there. You can have created an organization already using EmailAuthBackend, or plan to create the organization using LDAP authentication.

  2. Tell Zulip how to connect to your LDAP server:

    • Fill out the section of your /etc/zulip/settings.py headed "LDAP integration, part 1: Connecting to the LDAP server".
    • If a password is required, put it in /etc/zulip/zulip-secrets.conf by setting auth_ldap_bind_password. For example: auth_ldap_bind_password = abcd1234.

  3. Decide how you want to map the information in your LDAP database to users' account data in Zulip. For each Zulip user, two closely related concepts are:

    • their email address. Zulip needs this in order to send, for example, a notification when they're offline and another user sends a PM.
    • their Zulip username. This means the name the user types into the Zulip login form. You might choose for this to be the user's email address (sam@example.com), or look like a traditional "username" (sam), or be something else entirely, depending on your environment.

    Either or both of these might be an attribute of the user records in your LDAP database.

  4. Tell Zulip how to map the user information in your LDAP database to the form it needs for authentication. There are three supported ways to set up the username and/or email mapping:

    (A) Using email addresses as Zulip usernames, if LDAP has each user's email address:

    • Make AUTH_LDAP_USER_SEARCH a query by email address.
    • Set AUTH_LDAP_REVERSE_EMAIL_SEARCH to the same query with %(email)s rather than %(user)s as the search parameter.
    • Set AUTH_LDAP_USERNAME_ATTR to the name of the LDAP attribute for the user's LDAP username in the search result for AUTH_LDAP_REVERSE_EMAIL_SEARCH.

    (B) Using LDAP usernames as Zulip usernames, with email addresses formed consistently like sam -> sam@example.com:

    • Set AUTH_LDAP_USER_SEARCH to query by LDAP username
    • Set LDAP_APPEND_DOMAIN = "example.com".

    (C) Using LDAP usernames as Zulip usernames, with email addresses taken from some other attribute in LDAP (for example, mail):

    • Set AUTH_LDAP_USER_SEARCH to query by LDAP username
    • Set LDAP_EMAIL_ATTR = "mail".
    • Set AUTH_LDAP_REVERSE_EMAIL_SEARCH to a query that will find an LDAP user given their email address (i.e. a search by LDAP_EMAIL_ATTR). For example: 
      AUTH_LDAP_REVERSE_EMAIL_SEARCH = LDAPSearch("ou=users,dc=example,dc=com",
                                            ldap.SCOPE_SUBTREE, "(mail=%(email)s)")
    • Set AUTH_LDAP_USERNAME_ATTR to the name of the LDAP attribute for the user's LDAP username in that search result.

You can quickly test whether your configuration works by running:

/home/zulip/deployments/current/manage.py query_ldap username

from the root of your Zulip installation. If your configuration is working, that will output the full name for your user (and that user's email address, if it isn't the same as the "Zulip username").

Active Directory: Most Active Directory installations will use one of the following configurations:

  • To access by Active Directory username:

    AUTH_LDAP_USER_SEARCH = LDAPSearch("ou=users,dc=example,dc=com",
                                   ldap.SCOPE_SUBTREE, "(sAMAccountName=%(user)s)")
AUTH_LDAP_REVERSE_EMAIL_SEARCH = LDAPSearch("ou=users,dc=example,dc=com",
                                   ldap.SCOPE_SUBTREE, "(mail=%(email)s)")
AUTH_LDAP_USERNAME_ATTR = "sAMAccountName"

  • To access by Active Directory email address:

    AUTH_LDAP_USER_SEARCH = LDAPSearch("ou=users,dc=example,dc=com",
                                   ldap.SCOPE_SUBTREE, "(mail=%(user)s)")
AUTH_LDAP_REVERSE_EMAIL_SEARCH = LDAPSearch("ou=users,dc=example,dc=com",
                                            ldap.SCOPE_SUBTREE, "(mail=%(email)s)")
AUTH_LDAP_USERNAME_ATTR = "mail"

If you are using LDAP for authentication: you will need to enable the zproject.backends.ZulipLDAPAuthBackend auth backend, in AUTHENTICATION_BACKENDS in /etc/zulip/settings.py. After doing so (and as always restarting the Zulip server to ensure your settings changes take effect), you should be able to log into Zulip by entering your email address and LDAP password on the Zulip login form.

You may also want to configure Zulip's settings for inviting new users. If LDAP is the only enabled authentication method, the main use case for Zulip's invitation feature is selecting the initial streams for invited users (invited users will still need to use their LDAP password to create an account).

Synchronizing data

Zulip can automatically synchronize data declared in AUTH_LDAP_USER_ATTR_MAP from LDAP into Zulip, via the following management command:

/home/zulip/deployments/current/manage.py sync_ldap_user_data

This will sync the fields declared in AUTH_LDAP_USER_ATTR_MAP for all of your users.

We recommend running this command in a regular cron job, to pick up changes made on your LDAP server.

All of these data synchronization options have the same model:

  • New users will be populated automatically with the name/avatar/etc. from LDAP (as configured) on account creation.
  • The manage.py sync_ldap_user_data cron job will automatically update existing users with any changes that were made in LDAP.
  • You can easily test your configuration using manage.py query_ldap. Once you're happy with the configuration, remember to restart the Zulip server with /home/zulip/deployments/current/scripts/restart-server so that your configuration changes take effect.

When using this feature, you may also want to prevent users from changing their display name in the Zulip UI, since any such changes would be automatically overwritten on the sync run of manage.py sync_ldap_user_data.

Synchronizing avatars

Starting with Zulip 2.0, Zulip supports syncing LDAP / Active Directory profile pictures (usually available in the thumbnailPhoto or jpegPhoto attribute in LDAP) by configuring the avatar key in AUTH_LDAP_USER_ATTR_MAP.

Synchronizing custom profile fields

Starting with Zulip 2.0, Zulip supports syncing custom profile fields from LDAP / Active Directory. To configure this, you first need to configure some custom profile fields for your Zulip organization. Then, define a mapping from the fields you'd like to sync from LDAP to the corresponding LDAP attributes. For example, if you have a custom profile field LinkedIn Profile and the corresponding LDAP attribute is linkedinProfile then you just need to add 'custom_profile_field__linkedin_profile': 'linkedinProfile' to the AUTH_LDAP_USER_ATTR_MAP.

Automatically deactivating users with Active Directory

Starting with Zulip 2.0, Zulip supports synchronizing the disabled/deactivated status of users from Active Directory. You can configure this by uncommenting the sample line "userAccountControl": "userAccountControl", in AUTH_LDAP_USER_ATTR_MAP (and restarting the Zulip server). Zulip will then treat users that are disabled via the "Disable Account" feature in Active Directory as deactivated in Zulip.

Users disabled in active directory will be immediately unable to log in to Zulip, since Zulip queries the LDAP/Active Directory server on every login attempt. The user will be fully deactivated the next time your manage.py sync_ldap_user_data cron job runs (at which point they will be forcefully logged out from all active browser sessions, appear as deactivated in the Zulip UI, etc.).

This feature works by checking for the ACCOUNTDISABLE flag on the userAccountControl field in Active Directory. See this handy resource for details on the various userAccountControl flags.

Deactivating non-matching users

Starting with Zulip 2.0, Zulip supports automatically deactivating users if they are not found by the AUTH_LDAP_USER_SEARCH query (either because the user is no longer in LDAP/Active Directory, or because the user no longer matches the query). This feature is enabled by default if LDAP is the only authentication backend configured on the Zulip server. Otherwise, you can enable this feature by setting LDAP_DEACTIVATE_NON_MATCHING_USERS to True in /etc/zulip/settings.py. Nonmatching users will be fully deactivated the next time your manage.py sync_ldap_user_data cron job runs.

Other fields

Other fields you may want to sync from LDAP include:

  • Boolean flags; is_realm_admin (the organization's administrator permission) is the main one. You can use the AUTH_LDAP_USER_FLAGS_BY_GROUP feature of django-auth-ldap to configure a group to get this permissions. (We don't recommend using this flags feature for managing is_active because deactivating a user this way would not disable any active sessions the user might have; see the above discussion of automatic deactivation for how to do that properly).
  • String fields like default_language (e.g. en) or timezone, if you have that data in the right format in your LDAP database.
  • Coming soon: Support for syncing custom profile fields from your LDAP database.

You can look at the full list of fields in the Zulip user model; search for class UserProfile, but the above should cover all the fields that would be useful to sync from your LDAP databases.

Multiple LDAP searches

To do the union of multiple LDAP searches, use LDAPSearchUnion. For example:

AUTH_LDAP_USER_SEARCH = LDAPSearchUnion(
    LDAPSearch("ou=users,dc=example,dc=com", ldap.SCOPE_SUBTREE, "(uid=%(user)s)"),
    LDAPSearch("ou=otherusers,dc=example,dc=com", ldap.SCOPE_SUBTREE, "(uid=%(user)s)"),
)

Restricting access to an LDAP group

You can restrict access to your Zulip server to a set of LDAP groups using the AUTH_LDAP_REQUIRE_GROUP and AUTH_LDAP_DENY_GROUP settings in /etc/zulip/settings.py. See the upstream django-auth-ldap documentation for details.

Troubleshooting

Most issues with LDAP authentication are caused by misconfigurations of the user and email search settings. Some things you can try to get to the bottom of the problem:

  • Review the instructions for the LDAP configuration type you're using: (A), (B) or (C) (described above), and that you have configured all of the required settings documented in the instructions for that configuration type.
  • Use the manage.py query_ldap tool to verify your configuration. The output of the command will usually indicate the cause of any configuration problem. For the LDAP integration to work, this command should be able to successfully fetch a complete, correct set of data for the queried user.
  • You can find LDAP-specific logs in /var/log/zulip/ldap.log. If you're asking for help with your setup, please provide logs from this file (feel free to anonymize any email addresses to username@example.com) in your report.

Apache-based SSO with REMOTE_USER

If you have any existing SSO solution where a preferred way to deploy it (a) runs inside Apache, and (b) sets the REMOTE_USER environment variable, then the ZulipRemoteUserBackend method provides you with a straightforward way to deploy that SSO solution with Zulip.

Setup instructions for Apache-based SSO

  1. In /etc/zulip/settings.py, configure two settings:

    • AUTHENTICATION_BACKENDS: 'zproject.backends.ZulipRemoteUserBackend', and no other entries.

    • SSO_APPEND_DOMAIN: see documentation in settings.py.

    Make sure that you've restarted the Zulip server since making this configuration change.

  2. Edit /etc/zulip/zulip.conf and change the puppet_classes line to read:

    puppet_classes = zulip::profile::standalone, zulip::apache_sso

  3. As root, run /home/zulip/deployments/current/scripts/zulip-puppet-apply to install our SSO integration.

  4. To configure our SSO integration, edit a copy of /etc/apache2/sites-available/zulip-sso.example, saving the result as /etc/apache2/sites-available/zulip-sso.conf. The example sets up HTTP basic auth, with an htpasswd file; you'll want to replace that with configuration for your SSO solution to authenticate the user and set REMOTE_USER.

    For testing, you may want to move ahead with the rest of the setup using the htpasswd example configuration and demonstrate that working end-to-end, before returning later to configure your SSO solution. You can do that with the following steps:

    /home/zulip/deployments/current/scripts/restart-server
cd /etc/apache2/sites-available/
cp zulip-sso.example zulip-sso.conf
htpasswd -c /home/zulip/zpasswd username@example.com # prompts for a password

  5. Run a2ensite zulip-sso to enable the SSO integration within Apache.

  6. Run service apache2 reload to use your new configuration. If Apache isn't already running, you may need to run service apache2 start instead.

Now you should be able to visit your Zulip server in a browser (e.g., at https://zulip.example.com/) and log in via the SSO solution.

Troubleshooting Apache-based SSO

Most issues with this setup tend to be subtle issues with the hostname/DNS side of the configuration. Suggestions for how to improve this SSO setup documentation are very welcome!

  • For example, common issues have to do with /etc/hosts not mapping settings.EXTERNAL_HOST to the Apache listening on 127.0.0.1/localhost.

  • While debugging, it can often help to temporarily change the Apache config in /etc/apache2/sites-available/zulip-sso to listen on all interfaces rather than just 127.0.0.1.

  • While debugging, it can also be helpful to change proxy_pass in /etc/nginx/zulip-include/app.d/external-sso.conf to point to a more explicit URL, possibly not over HTTPS.

  • The following log files can be helpful when debugging this setup:

    • /var/log/zulip/{errors.log,server.log} (the usual places)
    • /var/log/nginx/access.log (nginx access logs)
    • /var/log/apache2/zulip_auth_access.log (from the zulip-sso.conf Apache config file; you may want to change LogLevel in that file to "debug" to make this more verbose)

Life of an Apache-based SSO login attempt

Here's a summary of how the Apache REMOTE_USER SSO system works, assuming you're using the example configuration with HTTP basic auth. This summary should help with understanding what's going on as you try to debug.

  • Since you've configured /etc/zulip/settings.py to only define the zproject.backends.ZulipRemoteUserBackend, zproject/computed_settings.py configures /accounts/login/sso/ as HOME_NOT_LOGGED_IN. This makes https://zulip.example.com/ (a.k.a. the homepage for the main Zulip Django app running behind nginx) redirect to /accounts/login/sso/ for a user that isn't logged in.

  • nginx proxies requests to /accounts/login/sso/ to an Apache instance listening on localhost:8888, via the config in /etc/nginx/zulip-include/app.d/external-sso.conf (using the upstream localhost_sso, defined in /etc/nginx/zulip-include/upstreams).

  • The Apache zulip-sso site which you've enabled listens on localhost:8888 and (in the example config) presents the htpasswd dialogue. (In a real configuration, it takes the user through whatever more complex interaction your SSO solution performs.) The user provides correct login information, and the request reaches a second Zulip Django app instance, running behind Apache, with REMOTE_USER set. That request is served by zerver.views.remote_user_sso, which just checks the REMOTE_USER variable and either logs the user in or, if they don't have an account already, registers them. The login sets a cookie.

  • After succeeding, that redirects the user back to / on port 443. This request is sent by nginx to the main Zulip Django app, which sees the cookie, treats them as logged in, and proceeds to serve them the main app page normally.

Sign in with Apple

Zulip supports using the web flow for Sign in with Apple on self-hosted servers. To do so, you'll need to do the following:

  1. Visit the Apple Developer site and Create a Services ID.. When prompted for a "Return URL", enter https://zulip.example.com/complete/apple/ (using the domain for your server).

  2. Create a Sign in with Apple private key.

  3. Store the resulting private key at /etc/zulip/apple-auth-key.p8. Be sure to set permissions correctly:

    chown zulip:zulip /etc/zulip/apple-auth-key.p8
chmod 640 /etc/zulip/apple-auth-key.p8

  4. Configure Apple authentication in /etc/zulip/settings.py:

    • SOCIAL_AUTH_APPLE_TEAM: Your Team ID from Apple, which is a string like "A1B2C3D4E5".
    • SOCIAL_AUTH_APPLE_SERVICES_ID: The Services ID you created in step 1, which might look like "com.example.services".
    • SOCIAL_AUTH_APPLE_APP_ID: The App ID, or Bundle ID, of your app that you used in step 1 to configure your Services ID. This might look like "com.example.app".
    • SOCIAL_AUTH_APPLE_KEY: Despite the name this is not a key, but rather the Key ID of the key you created in step 2. This looks like "F6G7H8I9J0".
    • AUTHENTICATION_BACKENDS: Uncomment (or add) a line like 'zproject.backends.AppleAuthBackend', to enable Apple auth using the created configuration.

  5. Register with Apple the email addresses or domains your Zulip server sends email to users from. For instructions and background, see the "Email Relay Service" subsection of this page. For details on what email addresses Zulip sends from, see our outgoing email documentation.

Adding more authentication backends

Adding an integration with any of the more than 100 authentication providers supported by python-social-auth (e.g., Facebook, Twitter, etc.) is easy to do if you're willing to write a bit of code, and pull requests to add new backends are welcome.

For example, the Azure Active Directory integration was about 30 lines of code, plus some documentation and an automatically generated migration. We also have helpful developer documentation on testing auth backends.

Development only

The DevAuthBackend method is used only in development, to allow passwordless login as any user in a development environment. It's mentioned on this page only for completeness.