Transcript Resource Sharing Over a Network

Resource Sharing Over a
Network
Guide to Operating Systems
Third Edition
Objectives
After reading this chapter and completing
the exercises you will be able to:
• Explain the principles behind sharing disks and
files on a network
• Set up accounts, groups, security, and disk and
file sharing on network server operating systems
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Objectives (continued)
After reading this chapter and completing
the exercises you will be able to:
• Set up disk and file sharing on client operating
systems
• Set up printer sharing on server and client
operating systems
• Discuss how network and Internet servers are
used for vast information-sharing networks
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Sharing Disks, Files and
Printers
• One of the first reasons for linking a
workstation’s operating system onto a network
• NetWare was early on the scene to enable file
sharing through a server
– by downloading a file from a file server
– by purchasing third-party software to create a
special shared drive
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Sharing Disks, Files and
Printers (continued)
• Share entire applications over the network
– Download the entire executable
– Only one version needed on the server
• Mapping
– enables a client workstation to attach to the shared
drive of another workstation or server
– drive letter assigned
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Sharing Disks, Files and
Printers (continued)
• Mounted volume
– term used in UNIX/Linux and Mac OS X for a mapped
drive
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Securing Shared Resources
• Potential security risk for non-authorized users
to access a file or use a printer
• Operating systems discussed in this book offer
security measures
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Sharing Disks and Files
Through Server Network
Operating Systems
• Examples of server network operating systems
that share disks and files over a network
– Windows 2000 Server
– Windows Server 2003
– UNIX/Linux
– Mac OS X Server
– NetWare
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Sharing Disks and Files
Through Server Network
Operating Systems
• Network administrator may establish security
– by assigning accounts, account passwords, groups,
and access privileges
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Windows 2000 Server and
Windows Server 2003
• Uses accounts, groups, and permissions
• Steps involved include setting up the following:
– Groups
– User accounts
– Account policies
– Permissions
– Shared disk and folders
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Windows 2000 Server and
Windows Server 2003
(continued)
• Use groups to manage resources and
permissions
– Local
– Domain local
– Global
– Universal
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Windows 2000 Server and
Windows Server 2003
(continued)
• Groups are defined as security or
distribution groups
• Security groups
– used to enable access to resources on a
standalone server or in Active Directory
• Distribution groups
– used for e-mail or telephone
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Windows 2000 Server and
Windows Server 2003
(continued)
• Container object
– entity that is used to group together resources in a
directory service
• Tree
– consists of one or more domains
• Forest
– houses one or more trees
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Windows 2000 Server and
Windows Server 2003
(continued)
• Universal group guidelines
– use global groups to hold user accounts as
members
– use domain local groups to provide access to
resources in a specific domain
– use universal groups to provide extensive access
to resources
– manage user accounts access
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Windows NT Server
• Trusted domain
– such as college.edu
– granted access to the resources in another
domain such as research.college.edu
• Trusting domain
– research.college.edu allows access to its
resources to college.edu
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Windows 2000 Server and
Windows Server 2003
(continued)
• Before any accounts are created, it is wise to
establish the account policies
• Three categories:
– Password security
– Account Lockout
– Kerberos security
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Windows 2000 Server and
Windows Server 2003
(continued)
• Password security options:
– enforce password history
– maximum password age
– minimum password age
– minimum password length
– password complexity requirements
– password storage using reversible encryption
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Windows 2000 Server and
Windows Server 2003
(continued)
• Account lockout options:
– account lockout duration
– account lockout threshold
– reset account lockout count
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Windows 2000 Server and
Windows Server 2003
(continued)
• Kerberos options:
– enforce user logon restrictions
– maximum lifetime for a service ticket
– maximum lifetime for a user ticket
– maximum lifetime for a user ticket renewal
– maximum tolerance for a computer clock
synchronization
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Windows 2000 Server and
Windows Server 2003
(continued)
• Share
– an object given a name and made visible to network
users
• Disk or folder - shared through its properties
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Windows 2000 Server and
Windows Server 2003 (continued)
• Share permissions:
– Read
– Change
– Full Control
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Windows 2000 Server and
Windows Server 2003 (continued)
• Dialog box in Figure 9-6 has a caching button
• Caching
– enables you to set up a folder so that it can be
accessed by a client, even when the client is not
connected to the network
• Web sharing
– files available on a Web server for HTML or FTP
access
– See Tables 9-2 and 9-3
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Windows 2000 Server and
Windows Server 2003 (continued)
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Windows 2000 Server and
Windows Server 2003
(continued)
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Windows 2000 Server and
Windows Server 2003 (continued)
• Troubleshooting a security conflict:
– review folder and share permissions
– take into account what happens when a folder or
files are copied or moved
– inherited properties
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UNIX and Linux
• User identification number (UID)
– each user account in UNIX is associated with a UID
• Group identification number (GID)
– users who have common access needs
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UNIX and Linux (continued)
• The password file (/etc/passwd) contains :
–
–
–
–
–
–
–
user name
encrypted password or a reference to the shadow file
UID
GID
information about the user
location of the user’s home directory
which shell to use
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UNIX and Linux (continued)
• Shadow file (/etc/shadow) contains password
restriction information :
– minimum and the maximum number of days
between password changes
– Information on when last changed
– Warning information about password expiration
– Amount of time that the account can be inactive
before access is prohibited
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UNIX and Linux (continued)
• Home directories
– areas on the server in which users store data
• Information about groups is typically stored in
the /etc/group file
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UNIX and Linux (continued)
• Permissions are granted on the basis of
– ownership
– group membership
– other (or World)
– all (all is not used in every version of UNIX, but is included in
Red Hat Enterprise Linux)
• Permissions are set up by using the chmod command
• Chmod has two different formats, symbolic and octal
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NetWare
• Novell NetWare server installation
– first task is to design a file structure
• Default directories:
– SYSTEM
– PUBLIC
– LOGIN
– HOME
– APPS
– DATA
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NetWare (continued)
• Net Administrator tasks:
– Set security on each directory, subdirectory, and on
particular files
– Create an account and account password for each
user
– Set up groups as a way to provide shortcuts for
managing security
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NetWare (continued)
• Search drive
– given drive letters such as S1 for the first drive, S2
for the second drive, and so on
• Difference between a mapped network drive
and a mapped search drive
– NetWare can execute a file on a search drive,
whether the file is in the main directory or in a
subdirectory under the search drive
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NetWare (continued)
• A login script is a file of commands associated with an
account or a group of accounts
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NetWare (continued)
• A user account can be set up in ConsoleOne
using several kinds of restrictions:
– Requiring a password
– Setting a minimum password length
– Requiring that a password is changed within a
specified interval of time
– The remainder are listed on page 453 of the textbook
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NetWare (continued)
• Administrator can grant rights to access
specific directories, subdirectories, and
files
• The rights control the ability to:
– Perform a directory listing
– Create a new directory, subdirectory, or file
– Read contents of a directory, subdirectory, or
file
– Write to the contents of a file
– Refer to the list on page 454 of the textbook for
the rest
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NetWare (continued)
• Objects
– such as user accounts, groups, printers, directories,
subdirectories, files, and other resources
• Novell Directory Services (NDS)
– stores information about objects
• Leaf objects
– store information about clients
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Mac OS X Server
• The Mac OS X Server is designed as a true server
– file sharing
– printer sharing
– managing network users and groups
– providing Web services
• Mac OS X Server
– can support up to several thousand users
– includes the Apache Web server software
– supports TCP/IP and AppleTalk
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Mac OS X Server
(continued)
• Included tools
– Server Admin
– Macintosh Manager
• Share points
– shared resources on a server
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Mac OS X Server
(continued)
• Logging of events can include:
– Login and Logout events
– Opened files
– Newly created files
– Newly created folders
– Deleted files and folders
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Accessing and Sharing
Disks and Files Through Client
Network Operating Systems
• Many operating systems
– include the ability to act as clients
– to map to disks and directories on servers
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Accessing and Sharing Resources
in Windows 2000 Professional
• Windows 2000 Professional
– Access a shared drive over the network
– Map the drive using My Network Places
• The steps for mapping a drive are shown on
page 457
• Same process for Windows 2000 Server
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Accessing and Sharing
Resources in Windows XP
• Uses My Network Places to locate and map
network drives
• Fastest way to access My Network Places is to
use the steps on page 458
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Accessing and Sharing
Resources in Windows XP
(continued)
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Accessing Shared Resources
via UNIX/Linux and Specialized
Utilities
• Network File System (NFS)
– provides file transfer capabilities
• NFS in Red Hat Enterprise Linux 3.0
– enable portmap
– enable rpc.mountd
– enable rpc.nfsd
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Accessing Shared Resources
via UNIX/Linux and Specialized
Utilities (continued)
• UNIX/Linux can access share Windows
2000/XP/Server 2003 with Samba
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Accessing and
Sharing Resources via Mac
OS X
• In Mac OS X, you connect to another computer that is sharing a
disk or folder by using the Go menu
• To mount a shared drive
– open the Go menu
– select Connect To
Server
– enter address of
server
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Accessing and
Sharing Resources via Mac OS X
(continued)
• Establish the network
identity and turn on
file sharing through
System Preferences
• Privileges are set in
order to enable
access
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Sharing Printing Devices
• Operating systems discussed in this
book have the ability to share printers as
well as disks, directories, and files
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Windows-based Systems
• Configure printing by using the Add
Printer Wizard
• Once a printer is set up, it appears in the
Printers folder
• In Windows XP and Windows Server 2003,
click Start, and click Printers and Faxes
• Right-click the printer to access menu
options
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Windows-based Systems
(continued)
• Windows 2000/XP/Server 2003 share
permissions:
– Print
– Manage Documents
– Manage Printers
– Special permissions
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UNIX/Linux
• UNIX printing
– log on to the UNIX server and printing to one of its
printers
– set up to use the BSD or the SVR4 spooling system
as describe in Chapter 5
• Red Hat Enterprise Linux 3.0
– GNOME Print Manager tool
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NetWare
• Shared printing
– queue-based printing
– Novell Distributed Print Services (NDPS)
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Mac OS X
• Methods of printer sharing
– can make a connected local printer available to
other computers running the Mac OS on a
network
– can attach to a shared printer offered by another
workstation on the network
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Network and
Internet Resource Servers
• Resource Servers
– NetWare
– UNIX/Linux
– Windows 2000/Server 2003
– Mac OS X servers
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Network and
Internet Resource Servers
• Functions
– e-mail
– e-commerce
– video-conferencing
– multimedia
– client/server applications
– web servers
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Summary
• Resource sharing is why networks exist and
are thriving
• Security is important for network resources
• Groups, user accounts, and permissions
permit or restrict access as determined by
the administrator
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Summary (continued)
• Client operating systems have utilities to
enable access or share resources over the
network
• Network server operating systems continue to
provide more and more ways to share
resources
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