Reflecting on another successful Interoperability Lab event

Engagement with partners is an integral part of achieving interoperability with Windows. In addition to helping users of the Microsoft Open Protocol Specifications, our team participates in a regular basis in interoperability labs dedicated to specific areas of focus of our partners.

Sun Microsystems is one our team’s most active partners. Recently, I had the opportunity to take part in the Sun’s IO lab hosted in the Microsoft Enterprise Engineering Center (ECC). The event focused on testing Solaris implementation against Windows in the areas of remote file sharing with extended security support, and Microsoft Distributed File System. It was a great adventure for me throughout the week. In this blog, I am reflecting on the event and sharing my experiences and story as a supporting Escalation Engineer.  

The Sun IO event was held at the ECC from 10/26 to 10/30. Prior to the event, the Protocol Engineering management worked closely together with the ECC program management to plan and set up a testing environment agreed upon with Sun. The environment included two forests, four domains with different domain functional levels, and a myriad of clients. A team of five attendees came from Sun primarily to test Solaris CIFS service with extended security support, and standalone DFS server under development. In the file sharing space, one key objective was to test Kerberos PAC support with Solaris (client or server) against a matrix of Windows clients and servers. Sun also planned to leverage the Microsoft Protocol Test suites to test their current implementation of SMB, KILE, PAC and DFS.

The team felt pleased with the excellent lab environment setup by the EEC as it provides the flexibility to experiment various scenarios. Solaris servers were installed either on physical machines or on virtual machines. On the first day, after the morning meeting, Sun’s team even requested a third forest with a specific functional level and Windows service pack, and it was created. This forest will be used for the Kerberos PAC testing.

Following the initial meeting, engineers from both Microsoft and Sun worked in configuring the testing environment. Sun’s engineers joined their machines to the lab network dedicated for the event and began compiling their software. From our side, we helped troubleshooting network issues and identifying the latest patches and hot fixes required to join Solaris to Windows domains. Others worked on compiling MIT KDC on a Solaris server. Later during the day, I began gathering more details about initial questions raised by Sun’s engineers regarding SMB/CIFS. The questions aimed at clarifying certain SMB/CIFS interoperability aspects in Windows-based implementations compared to Linux, Solaris, or Posix-based implementations. After some quick research and engagement with Microsoft subject matter experts, we had very interesting discussions on the topics of interest. 

The next day, the testing activities were getting substantial. I was called upon for consulting on a pass-through authentication issue. I decided to collect and analyze the resulting network trace, and ETW trace. As we resolved this scenario, and ensured the correct principal was initiating the SMB session, we ran into an interesting question on SPNEGO whereby the negotiation hint from the Solaris server would not contain a NTLM OID. In such a scenario, if the optimistic mechanism did not succeed, the Windows client would close the connection but this solely depends on the error that occurs during the authentication initiation. 

From now on, till the end of Day 3, I worked with two of Sun’s engineers and debugged a Kerberos PAC issue. After some brainstorming, we were all under the impression that this issue would be challenging because the Solaris server has to use exactly the same inputs and the same cryptographic algorithm Windows KDC used to generate the PAC server signature. The first phase of the investigation plan was to analyze Windows source code. The second phase was to capture Time Travel Traces (TTT) from the Windows KDC. It has also been critical to instrument the Solaris code and trace some key material, and encryption types passed to different calls during the server side of PAC verification. Invariably, I used the data from the Solaris syslog, and ran live debugging with Windows source attached. After a few hours of analysis, I asserted that the MIT API that was being leveraged by the Solaris server was producing the wrong key hash for the server signature. One of Sun’s engineers conducted code analysis and confirmed this. We then referred to the MS-PAC and MS-KILE documents and discussed the expected logic.

On Day 4, following the meeting with the security team, I was assigned to test LDAP interoperability of SASL between Windows Active Directory and Solaris LDAP clients. I worked with another Test Suites engineer to test various scenarios. We observed the Solaris bind security layer negotiation behavior with Windows Server 2008 R2. We also confirmed that the default Windows DC settings would allow LDAP operations to complete successfully via SASL.

The final day of my week was dedicated to wrap-up the issues that I had been tracking throughout the week. The joint debugging and testing efforts between the Sun and Microsoft teams have been very productive, and raised a few interoperability issues from both sides.

I was really impressed by the teamwork from Sun and Microsoft engineers and the depth of the testing activities. I will be pleased to work with them in another interoperability event in the future.

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