Internet Engineering Course

1
Internet Engineering Course

• OS Selection

2
Servers vs. Desktop Systems

• Servers
• Should not contain functionality not required for
  the intended function
• Minimal service set
• Dont 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!

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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

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Evaluation criteria

• Applications
• Stability and Reliability
• Security
• Scalability
• Usability
• Staff Issues
• Total Cost of Ownership (TCO)

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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?

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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!

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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)

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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.

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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.

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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.

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Applications cont.

• open source Applications
• Majority of these projects have been developed on
  Linux
• Unless they are platform neutral, theyll 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

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Applications cont.

• open source Applications
• Some open source applications (visit
  www.sourceforge.net)
• Apache
• BIND (Berkeley Internet Name Domain)
• DHCPd (Dynamic Host Configuration Protocol )
• 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)

13
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

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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 Windows.

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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

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Reliability and Stability cont.

• Reboot required even for minor changes
• Microsofts 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

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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.

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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.

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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

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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 (Extended Change Access
  Control List ) provided in Windows Support Tools

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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 dont 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.

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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.

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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!

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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.

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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

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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 specificaction.
• 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.

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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 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.

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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.

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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 you
  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

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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

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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.

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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).

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Summary cont.

• Comparatively unreliable, and thus resource
  intensive to maintain.
• 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.

34
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.

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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

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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

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Choosing a Linux Distribution cont.

• Support from server manufacturers mainly
• Red Hat Enterprise Linux
• SUSE Linux Enterprise Server
• Challenging
• Gentoo
• Debian
• Slackware
• Arch

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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 Enterprise Linux 5
• Replaced by Fedora Core in late 2003, officially
  sponsored by Red Hat
• Developed with community participation
• 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

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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

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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

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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

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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/2
  6/1/
• DistroWatch.com
• http//distrowatch.com/

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Miscellaneous
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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