How to Resolve Key Vault and VPN Gateway Configuration Conflict in Azure?

Hello Moazzem Hossain

Azure VPN Gateway and Azure Key Vault both manage keys and certificates, but their functions are distinct. Ensure that Key Vault is used solely as a secure storage for sensitive resources, and the VPN Gateway serves as the consumer. 

• Use Azure RBAC or Key Vault Access Policies to grant the VPN Gateway the least privilege access to the Key Vault. Provide the necessary access (e.g., get, list for secrets and certificates) to the VPN Gateway's managed identity.
• Import or create your certificates in Key Vault using the Key Vault Certificate feature. Use the Azure Key Vault Certificate format to avoid compatibility issues when retrieving and using certificates.
• When associating a certificate with your VPN Gateway, provide the URL of the certificate or secret in the Key Vault. Use PowerShell or Azure CLI to link the VPN Gateway with the certificates stored in the Key Vault.
• If the VPN Gateway supports a direct reference to Key Vault, avoid manually uploading the same certificates to the VPN server application to prevent duplication and ensure seamless updates.
• For certificates stored in Key Vault, configure auto-renewal to keep certificates up to date without manual intervention, ensuring the VPN Gateway always uses the latest versions.

To minimize risks and enhance security in your scenario, follow these best practices:

• Enable a system-assigned managed identity for the VPN Gateway (TBBD-VPN-Server) and assign it the necessary Key Vault permissions. This avoids the need to manage access keys manually.
• Restrict Key Vault access to trusted services by enabling the Key Vault firewall and granting access only from the VNet where your VPN Gateway resides. Use Private Endpoints to ensure traffic to Key Vault remains within your private network.
• Ensure that all keys, secrets, and certificates in Key Vault are encrypted at rest by default using Azure's built-in encryption capabilities. Leverage Key Vault’s Key Rotation Policies to enforce regular rotation of keys and certificates. For the VPN Gateway, ensure automated updates or a process for replacing certificates when rotated.

Hope the above answer helps! Please let us know do you have any further queries.

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