Restrict Zendesk Access to a Specific IP Address Using Conditional Access

Overview

This article walks through restricting Zendesk access to one or more approved IP addresses using Conditional Access in Microsoft Entra ID. When Entra ID is configured as the identity provider for Zendesk via SAML SSO, Conditional Access policies are evaluated at sign-in time — blocking access from any IP not on your approved list before a SAML assertion is issued to Zendesk.

The approach uses two components working together: 

• Named Locations:  A saved list of trusted IP addresses or CIDR ranges defined in 
  Entra ID. 
• Conditional Access policy:  A policy that blocks Zendesk sign-ins originating from 
  any IP not on the trusted list. 

Team Members vs End Users

Zendesk manages SSO separately for two distinct user populations. The Conditional Access policy will only apply to the population for which SSO is enforced through Entra ID. Confirm which user types are in scope before proceeding.

Please Note:  This article focuses on restricting team member access, which is the most common use case for enterprise IP-based controls. If your organization also enforces SSO for end users through Entra ID, the same Conditional Access policy will apply to both populations since they share the same Entra ID enterprise application.

Prerequisites

Before proceeding, confirm the following are in place:

• Microsoft Entra ID P1 or P2 license - required for Conditional Access.
• Conditional Access Administrator role or higher in Microsoft Entra ID.
• Zendesk enterprise app (SAML SSO) registered in your Entra ID tenant with the SAML configuration saved in Zendesk Admin Center and SSO assigned to team members or end users.
• SSO set to Redirect to SSO only in Zendesk — under Security > Team member authentication (or End user authentication), the authentication mode must be set to Redirect to SSO only. If Let them choose is selected, users can bypass Entra ID by signing in with Zendesk credentials directly.
• Security Defaults Disabled in Entra ID - Security Defaults and Conditional Access cannot run simultaneously.
• Known static IP address -  the public IP address or CIDR range of each approved location.
• Break-glass admin account -  must be excluded from this policy to prevent administrative lockout.

Important:  If your approved IP address is dynamic, this approach will not work reliably. You must use a static IP before implementing IP-based Conditional Access.

Step 1: Create a Named Location for Your Trusted IP(s)

A Named Location defines the trusted IP addresses that Entra ID will reference as a condition in the policy.

1. Sign in to the Microsoft Entra admin center at entra.microsoft.com
2. Navigate to Protection > Conditional Access > Named locations.
3. Select + IP ranges locations.
4. Name the location. For example: Trusted - Corporate Office
5. Check the Mark as trusted location checkbox.
6. Click + and enter your approved IP address or CIDR range. 

7.  Click Create.

Step 2: Create the Conditional Access Policy

Create a policy that blocks AWS access from any location not on your trusted list.

1. In the Entra admin center, navigate to Protection > Conditional Access > Policies.
2. Select + New policy.
3. Name the policy. For example, Block Zendesk - Outside Trusted IPs

Assignments: Users

1. Under Assignments > Users, select All users.
2. Under Exclude, add your break-glass admin account and any automation or service accounts that authenticate from dynamic IPs.

Assignments: Target Resources

1. Under Target Resources, select Cloud apps > Select apps.
2. Search for and select Zendesk.

Conditions: Locations

1. Under Conditions > Locations, set Configure to Yes.
2. Under Include, select Any location.
3. Under Exclude, select Selected locations, then choose the Named Location you created in Step 1.

Tip: This configuration reads: apply this policy to sign-ins from any location, 
except the trusted named location. Any Zendesk sign-in originating outside the 
trusted IP will be blocked before Entra ID issues a SAML assertion to Zendesk.

Access Controls: Grant

1. Under Access Controls > Grant, select Block access.
2. Click Select to confirm.

Enable Policy

1. Set Enable policy to Report-only.
2. Click Create.

Important: Do not set this policy to On immediately. A block policy applied to All 
users that is misconfigured will lock all users out of Zendesk instantly. Always validate in Report-only mode first. 

Step 3: Validate the Policy

Before enabling enforcement, confirm the policy is evaluating sign-ins correctly.

1. In the Entra admin center, navigate to Identity > Monitoring & health > Sign-in logs. 
2. Filter by the Zendesk application.
3. Open a sign-in from a user on your trusted IP and confirm the Conditional Access 
tab shows Would succeed. 
4. If available, review a sign-in from an untrusted IP and confirm it shows Would fail 
with the location condition listed as the reason. 
5. Investigate any unexpected Would fail entries for users on trusted IPs — this typically indicates the network is presenting a different egress IP than what is entered in the Named Location.

Tip:  Use the What If tool under Protection > Conditional Access to simulate how a specific user signing in from a specific IP would be evaluated without waiting for a real sign-in event.

Step 4: Enable the Policy

1. In the Entra admin center, navigate to Protection > Conditional Access > Policies.
2. Select the policy created in Step 2.
3. Change Enable policy from Report-only to On.
4. Click Save.

From this point forward, any Zendesk sign-in attempt from an IP address not included in your Named Location will be blocked. Entra ID will not issue a SAML assertion to Zendesk, and the user will be denied access at the identity provider level.

Please Note: Users who are already signed in to Zendesk when the policy is enabled will not be immediately signed out. The block takes effect on the next sign-in or token refresh, typically within 1 hour. Confirm that Redirect to SSO only is active in Zendesk under Security > Team member authentication to prevent users from bypassing Entra ID using Zendesk credentials directly.

Summary

The following table summarizes the full configuration process.