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Slack

Last reviewed: 6 months ago

This guide covers how to configure Slack ↗ as a SAML application in Cloudflare Zero Trust.

Prerequisites

  • An identity provider configured in Cloudflare Zero Trust
  • Admin access to a Slack Business+ or Enterprise Grid plan account

1. Add a SaaS application to Cloudflare Zero Trust

  1. In Zero Trust ↗, go to Access > Applications.
  2. Select Add an application > SaaS.
  3. For Application, select Slack.
  4. For the authentication protocol, select SAML.
  5. Select Add application.
  6. Fill in the following fields:
    • Entity ID: https://slack.com
    • Assertion Consumer Service URL: https://<YOUR_DOMAIN>.slack.com/sso/saml
    • Name ID format: The format expected by Slack, usually Email
  7. Copy the SSO endpoint, Access Entity ID or Issuer, and Public key.
  8. Select Save configuration.
  9. Configure Access policies for the application.
  10. Select Done.

2. Create a x.509 certificate

  1. Paste the Public key in a text editor.
  2. Wrap the certificate in -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----.

3. Add a SAML SSO provider to Slack

  1. In Slack, go to Settings & administrations > Workspace settings > Authentication.
  2. Select Configure.
  3. Turn on Test. Configuration changes will not apply until Configure is turned on.
  4. Fill in the following fields:
    • Service Provider Issuer URL: Ensure set to https://slack.com.
    • SAML SSO URL: SSO endpoint from application configuration in Cloudflare Zero Trust.
    • Identity Provider Issuer: Access Entity ID or Issuer from application configuration in Cloudflare Zero Trust.
    • Public Certificate: Paste the entire x.509 certificate from step 2. Create a x.509 certificate.
  5. Under Advanced Options, select Expand.
  6. For AuthnContextClassRef, ensure urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport is selected.
  7. Ensure Sign the AuthnRequest is turned off.
  8. For SAML Response Signing, turn on Sign the Response and Sign the Assertion.
  9. In the main configuration page under Settings, choose whether SSO is required, partially required, or optional for workspace members.
  10. (Optional) Under Customize, enter a Sign in Button Label.
  11. Test your set-up. If all works well, turn Test to Configure.
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