Office 365 desktop application is not working with Roaming Captive Portal Access method.

Products

• Cloud Secure Web Gateway - Cloud SWG

Issue/Introduction

When Roaming Captive Portal is used as WSS access method, Office 365 desktop application fails to get connected. The connections status will remain in “Trying to Connect” and clicking on the Send/Receive button will return a “The server is not available. Contact your administrator if this condition persists” error. 

 

Environment

Web Security Service

Roaming Captive Portal Access method

Office 365 desktop application

Cause

• In Roaming Captive Portal access method, all requests must be authenticated in order to determine the Tenant ID and enforce tenant-based policies. 
• Roaming Captive Portal authentication is based on Form Cookie Redirect. 
• The Office 365 user agent is exempted from RCP authentication because it breaks with Cookie redirect. 
• Unauthenticated requests except a CONNECT request are silently denied in Captive Portal access method (due to #1)

Resolution

This issue is due to a limitation in authenticating applications that are known to fail with cookie based authentication, such applications may not work with Roaming Captive portal access method.