Services for UNIX - Interoperability : Windows Server 2003 SP1

All (well, almost) about Client for NFS - Configuration and Performance

Ashish — Mon, 14 Apr 2008 08:42:00 GMT

All (well, almost) about Client for NFS - Configuration and Performance

I was looking at the referrals this blog gets and I noticed that a lot of times people look for information on Client for NFS in Services for UNIX, Windows Server 2003 R2 or in Windows Vista and come to this blog, but I don't really have much useful information on installation, configuration and performance on Client for NFS. Now, that will not be the case.

I have received requests to put together something about Client for NFS since there doesn't seem to be a detailed single document which talks about it. There are KB articles which cover installation and configuration of Client for NFS. There are also some of them about issues and registry settings to help optimize the settings for CNFS.

Since it has also been a long time I have spent time on this blog, I guess it's high time I talk about Client for NFS and add some value to my blog.

Client for NFS is a very important offering from Microsoft for small and big enterprises to integrate their Windows systems with existing UNIX based environment. It now comes with RFC2307 support as well. It's one of the most simple component among Services for UNIX components. Client for NFS doesn't really ask for any configuration/restarts in most of the installations and offers true out-of-the-box NFS connectivity. You can see in the following screen shot how Client for NFS can be added/removed if Services for UNIX software is already installed -

In Windows Server 2003 R2, you can find CNFS listed in "Microsoft Services for NFS" under "Other File and Print Services" -

And, on a Windows Vista Enterprise/Ultimate systems, here's how you can add it -

Once you have installed Client for NFS, you are ready to start connecting to UNIX NFS shares where anonymous access is allowed. If your environment doesn't have any such shares to test connectivity, you now need to configure this system to fetch UNIX identity information from an existing User Name Mapping server or configure one if it is not already running.

See these posts to learn more about User Name Mapping, especially Configuring User Name Mapping, Configuring User Name Mapping - Part 1, Configuring User Name Mapping - Part 2 (Simple Mapping) and Configuring User Name Mapping - Part 3 (Advanced Mapping).

With Windows Server 2003 R2 and Windows Vista, you can configure Client for NFS to directly fetch this information from AD if it's already there since they offer RFC2307 support. In fact, you can use any RFC2307 compliant directory service.

Configuration for Client for NFS is over with this and you can start using it. To connect to NFS shares, you can use the same built-in mechanisms as you would with a normal Windows share. In fact, you also get to use the familiar mount command to use.

Run the nfsadmin client command to see what options Client for NFS is configured to use. It might show something like this and is self-explanatory -

The File Setting in the above screen shot is the UMASK value Client for NFS will use when you create a new file or a folder on an NFS mount.

You can use NET command, the mount command which comes with it or the "Map Network Drive..." to map a drive to remote NFS shares. You can also browse the network and look for system which export NFS shares using "Network Neighborhood" or "My Network Places" since Client for NFS adds "NFS Network" under "Entire Network" for people who find it easier to search for machines they would like to connect to.

The mount command is useful because it lets you override the default parameter which applies to the NFS connections from this computer. The help for mount command can be displayed by running it with /? command line switch -

It uses a similar syntax like the NET USE command but it's not completely identical. For example, following is what you can use to map z: drive a remote NFS export -

mount \\servername\sharename z:

On the performance side, Client for NFS is tuned with parameters which suit most of the environments, but still there are things which can be tweaked to see if it helps you the way you want it -

Read and Write buffers - This can tuned from the MMC snap-in or per mount using the mount command. If you do it using the mount command, the syntax will look like -
mount -o rsize=16,wsize=16 \\servername\sharename drive
The default is 32 KB and works perfectly in most of the scenarios.
Case-sensitive mounts - Since Windows is not case-sensitive, enabling case-sensitive option while mounting the NFS shares can reduces the time taken to look up a file on the server. When this is option is not turned on (which is the default behavior), Client for NFS can perform multiple lookups to locate a single file and that will show up as a performance problem
This can only be done using the mount command and the syntax to do this is -
mount -o casesensitive \\servername\sharename drive:
8.3 name cache - As with Windows, Client for NFS also generates a 8.3 format name for the files on the NFS shares being accessed using Client for NFS. This adds up to the processing overhead. Turning off this option is recommended for performance gain. This is done with a registry change and this KB article explains the steps.
8.3 name generation in Windows Server 2003 R2 and later releases are permanently turned off for the same reason.
NFS Caching - NFS v3 uses caching to improve performance but this can be problematic in certain scenarios. Create "RemoteWriteCache" and "FileAttributeCache" DWORD values under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Client for NFS\CurrentVersion\Users\Default\Cache and set these to 0 to disable caching.
Folder Content Caching - Client for NFS also caches the folder contents for 30 seconds to avoid performing lookups to the NFS servers. This can sometimes result in delayed folder content refresh. Follow the steps in this knowledgebase article to disable it.
Set this registry setting to a value between 5-25.

Something worth taking a note - although the settings related to different aspects of caching may improves things on the client side, they can have performance percussions on the server side because when caching is not at work, the client may place more calls to the server and depending on the server and network conditions, it may cause the server to sweat more than it would normally. It's completely up to you to decide who would you like to work more for you - NFS client or the server.

Configuring User Name Mapping - Part 3 (Advanced Mapping)

Ashish — Fri, 25 Jan 2008 02:20:00 GMT

Configuring User Name Mapping - Part 3 (Advanced Mapping)

Simply said - when you map users and groups manually with their UNIX counterparts, it's called Advanced Mapping.

From the last post on User Name Mapping, you may be aware that Simple Mapping automatically creates maps for all users and group who have the same names in your Windows and UNIX environment. It is possible that you aren't lucky enough to have the same names for users and groups in both the environments. Sometimes, you would want better control on this aspect and may not want to map all the users and groups automatically.

Advanced mappings can be used in such cases. Easy to configure - turn off Simple Maps in User Name Mapping Configuration and map them manually. You can read this page to see how it can be done in a Windows Server 2003 R2 environment.

In Services for UNIX 3.x environments, you can do by using the Services for UNIX Administration console. Select User Name Mapping in the left pane, define the UNIX data source and click on Apply -

To proceed further, click on Mappings in the right pane. You can now click on Show User Mappings or Show Group Mappings depending on what you want to do -

Now, you can display the users/groups in both Windows and UNIX side. Select the objects in both lists and click on Add. You're done.

Configuring User Name Mapping - Part 2 (Simple Mapping)

Ashish — Tue, 02 Oct 2007 17:45:00 GMT

Configuring User Name Mapping - Part 2 (Simple Mapping)

Continuing the discussion from Configuring User Name Mapping - Part 1 - I will explain how to get Simple Mappings done in this post.

To rephrase, User Name Mapping (UNM) bridges the gap between the different user identification used in Windows and UNIX worlds. It's SID which identifies an object in Windows and Active Directory environment but it's UID and GID when it's a UNIX system in question. UNM is also a core authentication component in SFU World. When we are using it in conjunction with Server for NFS, UNM authenticates the incoming NFS access requests. With Client for NFS, it determines the effective UID and GID to be sent with the NFS requests to UNIX NFS servers.

UNM also provides a single point identity mapping database for all the machines running Server for NFS, Client for NFS and Interix/SUA components. For people looking for availability and clustering capabilities - you can configure UNM Server Pools and you can also run UNM on cluster nodes to achieve load balancing.

More on it later, back to Simple Mapping...

To match the Windows and UNIX identities, UNM uses Windows SAM or Active Directory to identify Windows users and UNIX files (/etc/passwd and /etc/group) or NIS domains as sources for identifying user and group information from UNIX perspective. This information is then mapped using Advanced and Simple Maps. Advanced maps are the ones that you create manually using the Administration Console while the Simple Maps are created automatically between the users and groups which have same names in Windows and UNIX databases.

It doesn't take much when creating Simple Maps apart from configuring basic things (I am assuming that you have installed the User Name Mapping service already and it's started).

First, you need to copy over the /etc/passwd and /etc/group files from your UNIX systems. Filter/Merge them so that they don't have any system account and duplicate UID/GID allocations. Now you can run this command -

mapadmin adddomainmap -d NTDomain -f Passwd/GroupDirectory

This command enables the Simple Mapping between the users and groups in Windows domain which is specified in place of NTDomain and the UNIX passwd/group files which have been stored under the directory specified in place of Passwd/GroupDirectory.

Now, you can run the following command to list all the maps -

mapadmin list -all

This lists all the maps which have been created. From my lab system -

The first command we ran is equivalent of making the following changes using the GUI -

Defining the UNIX files as the data source -
Enabling Simple Maps -
Displaying the Simple Maps -

It also takes care of enabling and creating Simple Maps for groups.

This KB article talks about installation and more command line options. I will soon post information in the form of Part 3 on UNM and talk about Advanced Mappings.

SFU hot fixes in email

Ashish — Fri, 07 Sep 2007 02:05:00 GMT

SFU hot fixes in email

Like any other Microsoft hot fix, you can also receive SFU hot fixes in your inbox - http://go.microsoft.com/?linkid=6294451

All you need is the KB article number which describes the fix you need. While we are talking about it, the following is also important to note -

"Hotfix Information

A Hotfix is a single package that includes one or more files that is used to address a very specific customer problem with a product. A supported Hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in the previous mentioned article. Only apply it to systems that are experiencing this specific problem. This Hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this Hotfix."

Why am I talking about it here?
At first, it doesn't sound like has anything to do with SFU or UNIX Interoperability components shipped with Windows. But, then users who use these components know that hot fixes get them out of many problems. I am sure a lot of them would prefer getting the hot fix using this form instead opening a case.

Before you rush to request the latest and greatest fixes for SFU or R2 components - be informed that there are a few of them which have very specific prerequisites and if they are not fulfilled, you may run in to other issues. Read below to know about them -

KB913030 - Applies only to Services for UNIX 3.5
You can install this hot fix on any system that's running Interix Subsystem, Server for NIS or Password Synchronization. It doesn't create any problems but is mentioned here since it contains some stability and reliability update for Interix subsystem and some utilities. You should install this fix before you install any other Interix subsystem hot fix which is newer than this one.

KB921599 - Applies only to Services for UNIX 3.5
Many people get confused with the information in the Kb article. This hot fix again applies only to Services for UNIX 3.5 Server for NIS and Password Synchronization components. You need this hot fix only if you have added a Windows Server 2003 R2 DC (or upgraded one of the DCs to R2) AND have also installed Server for NIS Identity Management for UNIX (IdMU) component which comes with Windows Server 2003 R2.

Since IdMU components in R2 use RFC2307 schema classes and attributes, when you install these components in SFU 3.5 environment, the installation process upgrades all of the NIS objects (NIS Domains, maps, users, groups etc.) to use R2 schema enhancements. This breaks Services for UNIX 3.5 Server for NIS and Password Synchronization components since they use a different schema. Installing this hot fix updates the SFU 3.5 Server for NIS and Password Synchronizarion binaries to use RFC2307 classes and attributes and helps SFU 3.5 and R2 IdMU components to co-exist.

KB936529 - Applicable to Services for UNIX 3.5
The previous post talks about it. Windows Server 2003 Service Pack 2 installation breaks SFU 3.5 Interix Subsystem and Password Synchronization components and this hot fix helps you to undo that. This hot fix should not be installed on Windows Server 2003 R2 SP2 systems because if you are using Password Synchronization IdMU component, this hot fix replaces the pswdsync.dll file with the one meant for SFU 3.5. As a result, Password Synchronization stop working.

If you have any questions about any SFU hot fixes, please use the Email button on the blog side bar and shoot me a mail.

How User Name Mapping works?

Ashish — Fri, 11 May 2007 23:28:00 GMT

How User Name Mapping works?

User Name Mapping is the core NFS authentication component in Services for UNIX, Windows Server 2003 R2 and Windows Vista. It bridges the gap presented by difference in user identification methods used by Windows and UNIX systems. It plays equally important role for Server for NFS and Client for NFS both.

When Server for NFS receives NFS access request from a UNIX client, all it gets is UID, GID and a set of auxiliary GIDs (which represents the secondary group memberships of that user in the UNIX world). Server for NFS then typically performs the following actions to authenticate the UNIX user who’s trying to access Windows NFS share –

Server for NFS uses User Name Mapping to obtain the corresponding Windows user name or group name.
After the user name is obtained, Server for NFS connects to a domain controller (for a domain account), or to local security authority for a local user –

The domain controller authenticates the domain account using Kerberos extension called Service-For-User (S4U).
Server for NFS Authentication is needed if the user account in question is a local account. Without Server for NFS authentication, the local security authority cannot authenticate the user and access to the UNIX client will be denied.

NFS authentication may not work for domain accounts if you have domain controllers running Window 2000 operating system. S4U extensions is not supported in Windows 2000 and earlier. In such cases, you need to install Server for NFS Authentication on all of your domain controllers to get the NFS authentication to work.

When you use Client for NFS to access a UNIX NFS share, it’s the UNIX NFS Server which authenticates the Windows user at the end. Since Windows users do not have UNIX-style UIDs and GIDs, the Client for NFS gets this information from the User Name Mapping service and uses them to connect to the UNIX NFS Server.

The NFS components included with Windows Server 2003 R2 and Windows Vista have RFC2307 support and can directly fetch the UIDs and GIDs from Active Directory. This post on this same blog talks more about this feature and User Name Mapping. The Active Directory domain, however, needs to be on the R2 schema level for that to work.

Windows Server 2003 SP2 breaks SFU

Ashish — Fri, 27 Apr 2007 20:03:00 GMT

Windows Server 2003 SP2 breaks SFU

We have already seen too many people reporting this - Windows Server 2003 Service Pack 2 installation breaks two functionalities in Services for UNIX 3.5 installations - Interix subsystem and Password Synchronization.

The root cause lies with SP2 unintentionally replacing the SFU 3.5 Interix binaries and Password Synchronization binaries with corresponding R2 binaries. The specific files that get replaced after installing SP2 are psxss.exe, psxdll.dll and pswdsync.dll. First two are part of the SFU 3.5 Interix subsystem and the last belongs to SFU 3.5 Password Synchronization component.

Microsoft is aware of this problem is working on a patch to address this issue.

Until the patch is ready, the only way out is to manually put the right binaries back in place. To do that, you can either copy the above mentioned files from some other working box that has SFU 3.5 installed or get the right drivers from Microsoft support.

While you ask Microsoft PSS for the right drivers, I would recommend asking for the binaries that were included with the Services for UNIX Security and Reliability rollup package 913030 since it contains the necessary SFU 3.5 binaries for Interix subsystem and Password Synchronization components.

After you've obtained the above hot fix 913030, follow the steps below -

Download and extract the hot fix on your system.
Among other files, you will get SFU35-KB913030-X86-ENU.EXE which you need to install.
Double-click on this file and complete the installation. At the end, the installation will prompt you to reboot the server and this prompt features just the OK button. DO NOT click on it yet.
Open a Command Prompt window, change to the folder where you have the SFU35-KB913030-X86-ENU.EXE file and run this -

SFU35-KB913030-X86-ENU.exe /x
This command extracts the files from the hot fix instead of kicking the hot fix installation.
That'll again ask you a folder location where the files from this hot fix should be extracted. Type a path and click on OK.
After extraction is complete, open this new path in Windows Explorer. Open the sfu35eng folder and here you can see all the files this hot fix updates.
Depending upon which component is broken on your system, copy the psxss.exe, psxdll.dll and/or pswdsync.dll files after verifying the version number (it should be 8.0.1969.38) to your %systemroot%\system32 folder.

Manual update of these drivers is needed since the wrongly replaced drivers have a version number corresponding to Windows Server 2003 R2 which is higher than that of the SFU 3.5 driver versions.
Come back to the hot fix window which is still waiting for you to click on the OK button. Click on OK and let your system reboot.
All should be fine now. If not, you probably need Microsoft PSS to help you with this.

There is likely to be a fix very soon. I would update this post whenever that happens.