Linux Integration: As Easy as Unix, But Not Getting Any Easier

The Linux tide is rising. The leader of the open source software movement is on its way to becoming as readily available as Microsoft Corp.'s Windows operating systems, at least from major hardware OEMs. Several computing systems are being sold with either Linux or Windows installed by vendors such as Dell Computer Corp. ( and its competitors.

But despite the wishes of countless open-source warriors, Windows 2000, like Windows NT before it, will establish a substantial home in the back offices of large enterprises. Both operating systems, in fact, will reside side-by-side in many back offices.

As Linux becomes more prevalent in enterprise environments, administrators are searching for ways to integrate the open-source operating system with entrenched Windows NT and Unix platforms. Because of its Unix pedigree, integrating Linux with other Unix machines may not be the biggest problem. Pitfalls lie in wait for IT organizations that want to deploy Windows NT and Linux alongside one another.

Keep in mind that most authorities say integrating Windows NT and Linux systems is essentially no different from integrating Microsoft’s operating system with any other Unix platform.

"From a development standpoint, our engineers have found that, indeed, Linux is a Unix derivative, so our development philosophy is the same as it is with traditional Unix platforms," says Yaacov Cohen, president of Mainsoft Corp. (, publisher of MainWin XDE, an integrated development environment for porting Windows application to Unix.

Ed Matthews, vice president of product development at Unix-to-Windows integration specialist Mortice-Kern Systems Inc. (, agrees.

"I don’t believe that the interoperability issues are any different than they are for any other Unix platform," Matthews says.

Most parties agree: Just about anyone with Unix experience can sit down in front of a Linux-based server or workstation and feel at home. As a result, IT managers can apply hard-learned best practices from previous Windows NT and Unix interoperability efforts to the task of integrating Windows NT and Linux.

According to Dan Kusnetzky, director of worldwide operating environments at International Data Corp. (IDC,, there are several considerations administrators must take into account before deploying Windows NT and Linux in tandem with one another, such as file sharing, application integration and coexistence, and Microsoft’s DCOM.

"Linux to NT integration can happen on a number of levels, ranging from whether or not you just want to make applications on one system available to users on the other, do you want them to share data, or do you want them to simply share files," Kusnetzky explains.

Consequently, when seeking to implement Linux systems alongside Windows NT systems -- or vice versa -- IT managers can make use of most of the tools that have been designed to either provide native Unix-like management features in a Windows environment, port native Win32 applications to the Unix environment, or facilitate file sharing between the two platforms.

File Sharing, and Then Some

Interoperability between Windows NT and Linux on any level often begins with the task of simple file sharing. In this regard, administrators can look to the open source software community’s successful Samba project. Samba is a freeware implementation of the SMB protocol.

"I think that above all else, SAMBA is indispensable when it comes to integrating Windows servers and Linux clients," says Jerry Carter, a network administrator at Auburn University ( who assisted in the implementation of a SAMBA-controlled Windows NT domain running on Solaris and Linux platforms at his school’s campus. "We have been able to implement a very solid and stable Windows environment for our end users, and we’ve been able to do it using open source software in the back room."

Most importantly, says Luke Kenneth Casson Leighton, a programmer at Internet Security Service (ISS, export research services and a member of the Samba development effort, most popular Linux distributions ship with Samba available as a readily installable package.

Samba, originally developed as a means to provide base-level, file-sharing services between Windows environments and common Unix platforms, has come a long way since its inception.

The Samba development team is working on a project -- dubbed Windows NT Domains for Unix -- that allows Unix platforms to operate as primary domain controllers (PDC) for Windows NT clients.

"It is a means to allow Unix servers to operate in an NT environment, whether those be NT clients or NT servers," Leighton says. "The first thing that we’ve already got working is Samba functioning as a member of an NT domain. The second thing that’s still in development is to have Samba be a PDC, including it being a PDC to other Samba servers as members of that domain."

The extensibility of Samba aside, the task of managing Windows NT and Linux systems deployed in tandem can’t be overlooked. Here again, this problem has largely been addressed by existing Windows and Unix integration tools.

The MKS Toolkit from Mortice-Kern, for example, offers a command-line environment for Windows NT that is essentially the same as a Unix command environment, including a full set of scripting commands, Korn shell and C-Shell consoles, and an implementation of Perl.

Mortice-Kern's Matthews says his company’s product can bridge the gap between the command-line Unix world and the predominantly GUI-based world of Windows NT.

"NT makes an assumption that all the world is a GUI, and MKS Toolkit just makes it easier to administer and develop on an NT machine in the traditional command-line mode," he indicates.

Application Integration and Coexistence

In any integration or interoperability effort, application support is a major concern. Companies like Hummingbird Systems Ltd. (, WRQ Inc. ( and the DataFocus subsidiary of Mortice-Kern, have traditionally provided PC X-Server tools that leverage the X protocol to enable Unix applications on Windows desktops. For many classic Windows NT and Unix integration scenarios, in which PCs were deployed as alternatives to X-terminals on client desktops, the task of application integration usually involved the choice of a good X-Server product.

IT managers may now want to run Windows applications on Linux because of its wide range of implementation scenarios, from low-end client device to high-performance clustered server. Such a design goal is prohibitively expensive on most other Unix platforms, but because of Linux’s low initial cost and it’s ability to run on legacy Intel hardware, more IT organizations are beginning to give this option a serious look.

MainWin XDE, an integrated development environment from Mainsoft can facilitate the porting of Windows applications to Unix platforms and is one tool that can help enable this latter scenario.

"We allow IT organizations to take Windows software and produce a native Linux application that will look like a native Windows application and will have the same functionality, but will benefit from the Linux operating system in terms of scalability and reliability. You’re getting the best of both worlds," Mainsoft’s Cohen says.

One of the most significant barriers in the path of any Windows-to-Linux porting initiative is Microsoft’s proprietary DCOM. Mainsoft’s MainWin XDE overcomes this barrier by bringing an implementation of DCOM to Unix platforms -- a fact not lost on Microsoft when it used MainWin XDE to bring its Internet Explorer 4.0 Web browser to several flavors of Unix.

"By getting DCOM, you can get a native way to link and to glue Linux desktops and Windows machines. This means that you can allow sharing of Microsoft office data, many kinds of data, and you can make Linux an equal player in your enterprise networks," Cohen says.

One solution for running Windows NT and other applications on Linux was given a big visibility boost in early January: GraphOn Bridges from GraphOn Corp. ( GraphOn Bridges allows client machines to run Windows or Unix applications through just about any kind of pipe, including low-bandwidth, dial-up and wireless connections. GraphOn Bridges works by Web-enabling Windows NT or Unix applications -- company officials say -- without any underlying software modifications.

Among Linux distributions, Corel Linux from Corel Corp. ( includes GraphOn Bridges with the base Linux distribution.


In 1999, a new application model came to the fore: the application service provider (ASP). In the ASP schema, a central server hosts applications for distributed clients who can access these programs over the Internet. Of the software platforms, enabling the ASP paradigm, Tarantella from Santa Cruz Operation Inc. (SCO, and MetaFrame from Citrix Systems Inc. ( are figuring heavily in Windows NT and Linux coexistence scenarios. Because ASP servers typically host applications that are executable in a number of disparate operating system environments, administrators can deploy Windows applications on either MetaFrame or Tarantella and allow Linux, Unix, Windows, Macintosh and other clients to access them. In the case of Tarantella, IT organizations can host 32-bit Windows applications on non-Win32 environments, such as Linux and several flavors of Unix.

MetaFrame is a software enhancement for Microsoft’s Windows NT Terminal Server Edition operating system that enables non-Win32 platforms, such as Macintosh or Unix clients, to access and remotely execute Windows applications. Using MetaFrame, administrators can configure applications on a Windows NT Server Terminal Edition box to be accessible to client operating systems of any stripe.

Where MetaFrame runs on the Windows platform, SCO’s Tarantella runs natively on a variety of Unix flavors -- platforms that have been designed from the ground up for hosting multiuser sessions. Andy Bozington, product marketing manager for Tarantella at SCO, says many administrators who are wrestling with the problem of providing manageable Windows applications to end users might opt to use a Tarantella solution on Linux.

"The key thing really is do you want to put your NT system in control of your deployment and of your environment?" Bozington asks. "There’s going to be some people who want to do this, but I certainly feel happier knowing that this application control platform is based on a Unix or a Linux system."

Auburn University’s Carter is one IT administrator who is happier hosting his Samba-controlled Windows NT domain on Unix than on Windows NT.

"Given the needs of our end users, they didn’t suffer because of what we chose to put in the server room," Carter explains. "In our environment, the infrastructure that we had built up is much more stable and manageable than if we’d said that we’re going to do the same thing with Windows NT servers."

Windows Integration Not Getting Easier

Linux benefits from the fact that it is as easy as its Unix brethren to integrate with Windows, but Microsoft is not driven to make it any easier to integrate its software with Linux.

With the release of the Windows 2000 operating systems, the prickly Windows-Linux détente may become more fragile. Windows 2000’s new security and directory features will make the prospects of interoperability with heterogeneous systems -- and especially with Unix-based systems like Linux -- substantially more difficult.

According to IDC’s Kusnetzky, but refuted by Microsoft, Redmond relies upon proprietary barriers to lock customers in to using its solutions -- almost always at the expense of interoperability with other products.

"Microsoft has chosen to erect barriers based upon proprietary APIs and proprietary communications barriers, and then it hides behind those barriers," Kusnetzky says. "[Microsoft] makes it more difficult for end users to integrate other solutions into their networks, making life difficult for IT managers."

One barrier is Windows 2000’s Kerberos-based security model, which could cause problems with management friendly solutions, such as the Samba project’s Windows-NT-domains-for-Unix initiative. Windows-NT-domains-for-Unix uses Microsoft’s MS-RPC domain control protocol, so that Windows NT clients have no idea that the Samba-based PDC to which they’re authenticating is not an NT server. In this sense, Windows-NT-domains-for-Unix doesn’t require any additional software on the client end.

Microsoft’s proprietary implementation of Kerberos and its Active Directory enterprise directory services will complicate matters by implementing a new, architecturally advanced version of this protocol.

"What this means for Samba is that [Windows 2000] is interoperable with Samba if it’s set in NT 4.0 backward compatibility mode," ISS’s Leighton says. "As soon as you switch off the interoperability, even with NT 4.0 domains, then Samba can’t interoperate as well."

But Windows 2000 can be deployed in Windows NT 4.0 backward compatible mode, an approach that most administrators in mixed environments will likely adopt. And despite Microsoft’s best efforts to the contrary, the open source software community will do its best to level the playing field.

"Microsoft’s idea seems to be that the time and monetary investment necessary to work these protocols out is financially unviable, but in the open source community that doesn’t work," Leighton comments. "For many open source developers, it’s like they have a vocation that they’re prepared to spend as much time as necessary to make this stuff work."

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