Unable to Sign in to the Microsoft Online Services Signin application from Windows 7 client located behind ISA firewall
- by Ravindra Pamidi
A while ago i helped a customer troubleshoot authentication problem with Microsoft Online Services Signin application. This customer was evaluating Microsoft BPOS (Business Productivity Online Services) and was having trouble using the single sign on application behind ISA 2004 firewall.The network structure is fairly simple with single Windows 2003 Active Directory domain and Windows 7 clients. On a successful logon to the Microsoft Online Services Signin application, this application provides single signon functionality to all of Microsoft online services in the BPOS package. Symptoms:When trying to signin it fails with error "The service is currently unavailable. Please try again later. If problems continue, contact your service administrator". If ISA 2004 firewall is removed from the picture the authentication succeeds.Troubleshooting: Enabled ISA Server firewall logging along with Microsoft Network Monitor tool on the Windows 7 Client while reproducing the issue. Analysis of the ISA Server Firewall logs and Microsoft Network capture revealed that the Microsoft Online Services Sign In application when sending request to ISA Server does not send the domain credentials and as a result ISA Server responds with an error code of HTTP 407 Proxy authentication required listing out the supported authentication mechanisms. The application in question is expected to send the credentials of the domain user in response to this request. However in this case, it fails to send the logged on user's domain credentials. Bit of researching on the Internet revealed that The "Microsoft Online Services Sign In" application by default does not support Outbound Internet Proxy authentication. In order for it to send the logged on user's domain credentials we had to make changes to its configuration file "SignIn.exe.config" located under "Program Files\Microsoft Online Services\Sign In" folder. Step by Step details to configure the configuration file are documented on Microsoft TechNet website given below. Configure your outbound authenticating proxy serverhttp://www.microsoft.com/online/help/en-us/helphowto/cc54100d-d149-45a9-8e96-f248ecb1b596.htm After the above problem was addressed we were still not able to use the "Microsoft Online Services Sign In" application and it failed with the same error. Analysis of another network capture revealed that the application in question is now sending the required credentials and the connection seems to terminate at a later stage. Enabled verbose logging for the "Microsoft Online Services Sign In" application and then reproduced the problem. Analysis of the logs revealed a time difference between the local client and Microsoft Online services server of around seven minutes which is above the acceptable time skew of five minutes. Excerpt from Microsoft Online Services Sign In application verbose log: 1/26/2012 1:57:51 PM Verbose SingleSignOn.GetSSOGenericInterface SSO Interface URL: https://signinservice.apac.microsoftonline.com/ssoservice/UID1/26/2012 1:57:52 PM Exception SSOSignIn.SignIn The security timestamp is invalid because its creation time ('2012-01-26T08:34:52.767Z') is in the future. Current time is '2012-01-26T08:27:52.987Z' and allowed clock skew is '00:05:00'.1/26/2012 1:57:52 PM Exception SSOSignIn.SignIn Although the Windows 7 Clients successfully synchronized time to the domain controller for the domain, the domain controller was not configured to synchronize time with external NTP servers. This caused a gradual drift in time on the network thus resulting in the above issue. Reconfigured the domain controller holding the PDC FSMO role to synchronize time with external time source ( time.nist.gov ) and edited the system policy on the ISA server firewall to allow NTP traffic to time.nist.gov Configure the time source for the forest:Windows Time Servicehttp://technet.microsoft.com/en-us/library/cc794937(WS.10).aspx Forced synchronization of Windows time using the command w32tm /resync on the domain controller and later on the clients each of which had corrected the seven minutes difference. This resolved the problem with logon to Microsoft Online Services Sign In.
