Internet Engineering

OS selection

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