Servers vs. Desktop Systems
Servers Should not contain functionality not required for the intended
function Minimal service set
Don’t install anything unless you really need it Avoid unnecessary exposure to new risks
Faster with redundant components Increased reliability Has more of everything
Much more customizable To perform specific tasks and optimizing them to do so
Administration and maintenance requires special training Security, Reliability, Stability and … are highly critical
Standardizing on a single OS for all purposes is not a goal!
Operating Systems we will study Mainly
Microsoft Windows Server family Linux
Somewhat OpenBSD from BSD family
There are many others that we do not study here Other variants of UNIX
Solaris, HP/UX, AIX Other variants in BSD category – FreeBSD, NetBSD, … Other variants in GNU category – GNU/Hurd, GNU/Mach, … …
And so many other OSs out there
Evaluation criteria
Applications Stability and Reliability Security Scalability Usability Staff Issues Total Cost of Ownership (TCO)
Applications
OS must support the application you will run! e.g. Exchange Server OS = Windows A constraint for choosing OS
If needs are identified but no specific product Look for the product and OS that supports it side by side
You are not limited to some specific OSs. Will not result in an OS that is difficult to support or costly. Less diversity in OSs is desirable (standardizing server OSs)
For selecting OS Look at what is generally available on the platform. What is included in the OS by default?
Applications cont.
Supplementary applications Intended to supplement a function of OS
Resource Kit/Support Tools for Microsoft Windows Unix tools for windows
Native OS completeness There are no functions that an administrator (skilled in
Perl/shell scripting) cannot do in UNIX systems Windows administrators have difficulty doing management
tasks without third party or supplementary utilities OS vendor is not supposed to support third party utilities and the
side effects they may have!
Applications cont.
Niche Area Support Greater diversity of applications available on Windows
Windows is great from this point of view Diversity in Windows and Linux family
Specific products may not run across the entire family Enough high quality server products for Linux Newer system now necessarily backward compatibe OpenBSD
A lot less third party products than either Windows or Linux Includes compatibility modes with several OSs
It should not be used extensively (e.g. Many Linux applications OS should be Linux)
Applications cont.
Application Integration Difference between integrated and integrable!
Features of Microsoft products works better with/only with Microsoft products!
Usage of one Microsoft product will lead to use of other Microsoft products Less tension to be compliant with other products.
Their implementations are not fully compliant with standards and therefore other implementations.
Other products should try to be integrable! Application support
Windows is the best, Linux is second and OpenBSD is third.
Applications cont.
Market Products Small vendors cannot afford to support various OSs
They are pulled towards Windows Server family Cause: Growth of various Windows based market applications
Windows NT started with a target bellow the high-end commercial UNIX systems Enhancements in each release Higher performance market
Reducing costs of an application Major advantage for small businesses
Linux entering the server market Linux will be a more obvious choice for small businesses.
Applications cont.
Included With Core OS Windows
File and print services, DNS, DHCP, IIS, FTP and other additional components
Linux and OpenBSD Includes much more standard Internet servers
Even support for Microsoft file and print sharing
As open source operating systems are free, one might say that any free software that runs on the OS is part of it.
Applications cont.
open source Applications Majority of these projects have been developed on Linux
Unless they are platform neutral, they’ll run on Linux with less effort than any other OS
Microsoft repeatedly made system design decisions that Make little or no technical sense, but make excellent business
sense, i.e. they make it more difficult and expensive for a developer to port a Windows application to other OSs.
open source is by no means a UNIX only phenomena, but Most open source development has been done on UNIX systems With the UNIX like open source operating systems, Linux and
BSD family, playing the leading roles
Applications cont.
open source Applications Some open source applications (visit www.sourceforge.net)
Apache BIND DHCPd PHP, Perl, Python Web traffic analysis packages like Webalizer, Analog MySQL, PostgreSQL Snort, PF, IP Filters, GuardDog NTP vsFTPd OpenOffice (replacement for Microsoft Office Suite) GIMP (replacement for Adobe Photoshop)
Applications cont.
OS Versions and Fragmentation Every several years, Microsoft introduces a fundamentally
different operating environment or system with major changes in the UI. Windows is designed to hide technical details, but these
changes introduces a major learning curve! Technical users may effectively loose a significant part of their
knowledge of how Windows works and need start over with the new system
These differences are mostly seamless from one version of UNIX to another
Applications (Summary)
There are many more applications for Windows Not all needed functionalities are included in the OS
Enough products available for the cost of the OS that some businesses can run mostly on open source solutions
As Linux is eating into Windows server market share, expect the application advantage for Windows servers to shrink and perhaps disappear.
Maintaining an application for Linux and other UNIX variants is minor compared to UNIX and Windows.
Reliability and Stability
Both are related to bugs. Stability
Relative resistance to crashes and lessening their affects Bugs and incompatibilities may cause crashes
Reliability Specific functions stop responding or return invalid results Odd behavior!
Availability Affected by thing related to reliability and stability To do and keep doing what they are supposed to do
Least possible amount of time staff spend troubleshooting problems
Reliability and Stability cont.
Reboot required even for minor changes Microsoft’s origins in single user systems Is not a part of UNIX or mainframe environments
Some systems become less stable for longer uptimes Rarely necessary for UNIX systems
Windows flaws in architectural design Windows registry Incredibly confused directory structure and its adverse
impact on system recovery System management functions contained in large complex
GUI programs mostly with no command-line counterparts
Reliability and Stability cont.
Windows registry Central repository for configuration data and … The fallacy is that registry data is accessed by key name.
Little fundamental difference between accessing entries in registry and files in different directories with different filenames
Numerous binary tree lookups, in a large deeply nested structure, become quite resource intensive Confirmed by the fact that Windows systems slow with age as
software is added UNIX systems do not slow with age due to software installs.
Reliability and Stability cont.
Windows GUI Interface Hampers Administrators Complex GUIs contributes to reliability issues
Such programs are harder to write and more likely to have their own bugs
Often, no alternative interface is provided Bug in management interface will result in inability to perform
some administrative tasks
In the UNIX world, essentially all administrative tasks are performed by relatively simple command line programs that do only one specific thing.
Reliability and Stability cont.
Linux Stability There is no need to ever reboot except for a kernel or
hardware upgrade or change. Registry problem is not applicable to Linux
OpenBSD Said to be the most stable and most reliable OS Clean code base Development model
Security
File Systems FAT lacks primary permissions and security facilities
needed for a server environment. UNIX allows controls only by owner, group and other. Each
of these can be set to any combination of read, write and execute. chmod
NTFS is much more customizable and provides flexible access control list capabilities. Windows GUI, xcacls provided in Windows Support Tools
Security cont.
Password Hashes Windows passwords are weaker and easier to break.
LANMAN hash BSD MD5 is one of the strongest hashes
Novice administrators really don’t know what they are doing! Making things easy is not that good!
Default Installations Previously default installation of Windows Server and
related network services made it much more easier to attack and exposed the system to many risks.
Unix default installation has basic security provisions. You have to enable anything you want.
Security cont.
Development Model, Bug Fixes, Security and Reliability Linux
The kernel appears to be under pretty much continuous development and more than one version is being developed simultaneously.
Development is a purely volunteer, non-commercial activity. Windows
Microsoft is the largest software company in the world and is purely commercial.
Microsoft responds in a reasonably timely fashion to reported and serious security bugs. It's primarily such bugs that their security alerts describe.
Security cont.
OpenBSD OpenBSD is the most secure OS available They try to find simple software bugs and they believe that
they are the origin of security issue. Secure by default
All non-essential services are disable by default Four years without a remote hole Outstanding open implementation of security standards. Unix Signal Handler and Open Software Fixes
Fix was available the day after the problem was announced publicly!
OpenBSD Daily Security Audit enabled by default
Scalability
Meanings How many processors/How much memory in a single
machine, an operating system is capable of supporting. Cluster of machines that work together to solve a common
problem. Recent projects of this type have consisted of hundreds to
thousands of Intel CPUs running Linux.
System Performance Confusing benchmarks about performance. No general statement on this issue.
Scalability cont.
Hardware Requirements Windows has GUI in its kernel
It need reasonably high hardware specifications. Most Linux servers installations do not have X-Windowing
System. Hardware specifications of Linux is much smaller than
Windows. Price Performance Ratio
The starting software cost for a public, Windows 2000 web server, is effectively over $4000.
There exists free Linux distributions and also commercial ones which costs much less than Windows servers
Scalability cont.
Relocating Server Applications Deep understanding of server status will result in wise
decision on relocating server applications. Decision support
Windows’ Task Manager or Performance Monitor UNIX’s ps command or Performance Analyzers like atop
Duplicated UNIX machines do not need to be kept as replicas. Application server load can be broken up between two machines. Duplication and Load Balancing Highly modular and so highly customizable Migrating Windows functions nearly always means building
new machines from scratch. Difficult to duplicate the settings!
Usability
Ease of Use ≠ Ease of Learning Ease of use often regarded as one of the most important
characteristics of any software product. Ease of learning is not often used.
Ease of use is nearly always used to mean that a product is easy to learn to use.
Normally means how easily a user new to a product can figure out how to perform a specific action.
Documentation, architecture, support, training and design GUI tools
May also make system administration tasks easy to learn. May make repetitive task very burdensome
Such tasks can make use of a system scheduler.
Usability cont.
Windows Lacks Automation Automating the task in Linux by scripts In Windows also possible but is very cumbersome in
comparison with Linux Automating the procedures that has no counterpart other than
GUI interface should be done with e.g. emulating mouse events or scripting utilities like AutoIt that does somehow ease this job! (Surely not reliable)
Easy to use learn Windows tools, become cumbersome to use as the tasks become more repetitive.
There are no scripting skills that are routine part of Windows administration Even batch programming skills, as simple (and limited) as that
"language" is, have largely fallen into disuse.
Usability cont.
Most Windows administrators are entirely dependent on the GUI management interface, and even where it should be obvious that something should be automated, do not have the knowledge or skills to do it.
UNIX administrators, in contrast, are normally skilled in at least one scripting language, and routinely expect to automate repetitive parts of their jobs.
Windows server systems have a pro novice bias and that UNIX systems have an anti-novice bias.
Usability cont.
Support Options Windows
Microsoft Knowledge Base, Customer Support, Consultants Most of the things are solved easily if you have employed a guru
consultant. The really good ones can solve seemingly very difficult problems, with ease
Gurus are expensive to employ and cheap ones learn on your job. Linux
Community Support, Commercial Support (e.g. RHEL), Gurus After gaining mastery and enough experience your are relaxed. It does not hide anything from you, so you can come up with the
solution. Google your problem and there should be a discussion about it in
a community
Staff Issues
UNIX administrators cost more than Windows ones. Main factor = Cost per machine From all previous discussions it is resulted that
maintaining a Linux server needs less effort that Windows one. So the staff cost is not a major factor as might be
considered at first
Total Cost of Ownership (TCO) Microsoft says TCO of Windows is much lower than Linux Factors
License Support Staff …
Windows license price How many simultaneous client connections? What server applications?
UNIX systems require more up-front learning effort. Security, Stability and Reliability
Moving to security, Linux is more secure in a default install Given normal installs by typically trained administrators Windows
systems are much less stable than Linux installs.
Summary
No operating system is perfect or even close, even when limited to server only or desktop only roles. Tradeoff
Windows servers With sufficient resources, they can be made stable. Because of variety of third party applications , it may be
possible to "do more" on Windows servers than other platforms.
As a particular matter, they rarely live up to their promise. Contain enormous array of unused features (may not be
easy to disable, for instance kernel customization).
Summary cont.
Comparatively unreliable, and thus resource intensive to maintain.
Theoretically, they can be made secure, as their built-in security functions are more sophisticated than standard UNIX security facilities. Very labor intensive and will result in a machine that will not
look like a Windows server. Given the complexity of Windows, tools and middleware
used to build the applications, and the applications themselves, it's absurd to think that all the security related bugs can be found and fixed. Only hope that the holes that exist are sufficiently difficult and
obscure, that no skilled malicious intruder actually finds them. Best hardware support among other OSs.
Summary cont.
Linux The default security characteristics of Linux depend on the
distribution and install options chosen. Linux has been used to build powerful parallel supercomputers
so it unquestionably clusters well The newest kernels should be comparable to Windows on
multiprocessor systems. Linux has a very large range of applications, both commercial
(proprietary) and open source. Linux has by far the largest number of open source applications. All business needs can be met by Linux applications. Linux has the best and most diverse free support available, which
is often better than traditional commercial support.
Choosing a Linux Distribution Some server candidates
Commercial Red Hat Enterprise Linux SUSE Linux Enterprise Server Mandriva Corporate Server
Non-commercial Gentoo Debian Fedora Slackware Arch
Choosing a Linux Distribution cont. Differences
Base operating system Some customization, e.g. init scripts, kernel Generally binary compatible
Software management and updating YUM APT Smart Synaptic
Hardware management Kudzu of Red Hat Non-commercial distros never contain proprietary drivers.
Proprietary extras
Choosing a Linux Distribution cont. Support from server manufacturers mainly
Red Hat Enterprise Linux SUSE Linux Enterprise Server
Challenging Gentoo Debian Slackware Arch
Choosing a Linux Distribution cont. Red Hat
Founded in 1994 by Bob Young and Marc Ewing Leader in development, deployment and Management of Linux
and open source solutions for Internet infrastructure Last version in the Red Hat Linux product line Red Hat Linux 9
Replaced by Fedora Core in late 2003, officially sponsored by Red Hat
Developed with community participation Has a short life-span Serves mainly as a testing base for Red Hat Enterprise Linux Widely used, excellent community support, lots of innovation
up2date and YUM as package managers (RPM) Red Hat Enterprise Linux products best supported by hardware
vendors among other Linux distributions Very good commercial support
Choosing a Linux Distribution cont. SUSE (formerly SuSe)
Established by a group of German developers in 1992 Adopted RPM package management format Easy to use YaST configuration tool Frequent releases Excellent documentation Acquired by Novell in late 2003 Professional attention to detail YaST (RPM), third-party APT (RPM) repositories available
as package managers
Choosing a Linux Distribution cont. Gentoo
Created by Daniel Robbins, a former Stampede Linux and FreeBSD developer
A source-based distribution Various levels of pre-compiled binary packages to get a basic Linux
system up The idea is to compile all source packages on the user's computer
Highly optimized for the computer architecture it is built on Long and tedious system installation Occasional instability and risk of breakdown
Software packages kept in a central repository Usually kept highly up-to-date and available within days Painless installation of individual software packages Highly up-to-date Superb documentation Distribution tailored to user's needs Portage (SRC) as package manager
Choosing a Linux Distribution cont. Debian
Started by Ian Murdock in 1993 Totally free, completely non-commercial Complete package set (about 16000 packages) Community support Most advanced package manager available
APT (DEB) Needs knowledgeable, hands-on user Three release branches
Stable Long period between stable releases The stable version tends to be out-dated
Testing Unstable
CE Servers
CE Fedora core 4
At the time of the new installation of CE, the administration team had not made decision to move toward Debian, so Fedora was chosen (The team is willing to change it to Debian)
Shell Debian Sarge
Cabinet Debian Sarge
Netserver FreeBSD
Tailored for stable network services we wanted to provide (DHCP, DNS, Firewall, Mail Queue, …)
Client management server Windows 2003 Enterprise Edition
For managing Windows clients you have to run Windows! AntiVirus, Patch Management and Client Management server
Note
Information provided in this presentation are not accurate and may be out of date.
There are many fundamental changes in Windows Server 2003 and Linux Kernel 2.6. Most parts of this presentation are based on Windows NT
and 2000 and Linux Kernel 2.4. Microsoft tries to provide a better command line interface
Windows Management Instrumentation Command-line (WMIC) tool is a great pace! Read about it and try it… // TODO: Try wmic.
Resource Kit/Support Tools // TODO: Download Windows Support Tools and try the tools.
References
GeodSoft: Linux, OpenBSD, Windows Server Comparison http://geodsoft.com/opinion/server_comp/
Software in Review – The differences between Linux distributions http://www.softwareinreview.com/cms/content/view/26/1/
DistroWatch.com http://distrowatch.com/
Miscellaneous
Category OSes Origin of code?
GNU GNU/Linux, GNU/HURD, GNU/Mach, GNU/BSD
Free Software Foundation; kernels developed separately except HURD. The Linux kernel was originally written by Linus Torvalds, and is currently maintained by him.
BSD FreeBSD, OpenBSD,
NetBSD, DesktopBSD, BSD/OS
UC Berkeley, originally; each project has been developed separately since the early-mid 1990s, however.
Unix Solaris, AIX, IRIX,
HP/UX, Tru64, UnixWare, OpenServer
Bell Labs (AT&T) developed the original Unix code. UNIX is now a trademarked operating system certification program instead of an operating system, and no longer requires that a compliant OS contain AT&T Unix source code to achieve brand certification. Despite that, all of the extant Unix derivatives are compliant with at least one published UNIX standard.
Darwin Darwin, OS X Based on the NeXTSTEP operating system, which used the Mach kernel and some FreeBSD programs and networking code. OS X is developed from Darwin.
Minix Minix Originally written by Andrew Tanenbaum, but now mostly developed by a handful of others
Miscellaneous cont.
BSD Family OpenBSD was an outgrowth of NetBSD
Split later with the goal of creating a reliable and secure OS OpenBSD is the most secure OS available
NetBSD is known for running on more hardware platforms FreeBSD split from NetBSD
Developers wanted to optimize the system for perfomance on Intel processors
Fastest OS that runs on Intel systems