Download siskiyous.edu

Network+ Guide to Networks
5th Edition
Chapter 9
Network Operating Systems
Objectives
• Describe characteristics common to all NOSs
(network operating systems)
• Compare and evaluate NOSs to select the right one
for your Network
• Define the requirements for and features of the
Windows Server 2008 NOS
• Define the requirements for and features of UNIX
and Linux NOSs
• Create users and groups and assign file permissions
on systems running Windows Server 2008 and
UNIX
Network+ Guide to Networks, 5th Edition
2
Characteristics of Network Operating
Systems
• Based on client/server architecture
• NOS manages resource sharing
• NOS provides many other functions
– Some built in
– Some configured at installation
• Default, customizable settings
• NOS components vary by NOS version and type
Network+ Guide to Networks, 5th Edition
3
Network Operating Systems and Servers
• Networks use servers exceeding minimum hardware
• Determining optimal server hardware
– Questions
•
•
•
•
•
What kinds of applications will run on the server?
How many clients will connect to the server?
How much storage space will each user need?
How much downtime, if any, is acceptable?
What can the organization afford?
Network+ Guide to Networks, 5th Edition
4
Network Operating Systems and
Servers (cont’d.)
• Determining optimal server hardware (cont’d.)
– Applications influence:
• Type of application
• Resources used
• Processing burden
– Vendor reputation requirements
• High quality, dependability, excellent technical support
• Reliable server
– Spend as much as necessary
• Component failure: widespread effects
Network+ Guide to Networks, 5th Edition
5
Client Support
• Important NOS function
– Allows efficient communication, resource sharing
• NOS client support tasks
–
–
–
–
–
Creating and managing client accounts
Enabling clients to connect to the network
Allowing clients to share resources
Managing clients’ access to shared resources
Facilitating communication between clients
Network+ Guide to Networks, 5th Edition
6
Client/Server Communication
• Logon process
• Redirector
– Intercepts requests, determines where to handle
• File access protocol
– Windows XP client communication with Windows
Server 2008
• CIFS (Common Internet File System)
• Older protocol SMB (Server Message Block)
– Broad support allows every client type to
authenticate, access resources
Network+ Guide to Networks, 5th Edition
7
Client/Server Communication (cont’d.)
Figure 9-1 A client connecting to an NOS
Network+ Guide to Networks, 5th Edition
8
Client/Server Communication (cont’d.)
• Middleware
– Translates requests, responses between client,
server
• 3-tier architecture
– Client/server environment incorporating middleware
Network+ Guide to Networks, 5th Edition
9
Client/Server Communication (cont’d.)
Figure 9-2 Middleware between clients and a server
Network+ Guide to Networks, 5th Edition
10
Users and Groups
• After NOS client authentication
– Client gains access to NOS services, resources
• Administrator account
–
–
–
–
Most privileged user account
Unlimited rights to server, domain resources, objects
Created by default
Root on UNIX or Linux systems
Network+ Guide to Networks, 5th Edition
11
Users and Groups (cont’d.)
• User names
– NOS grants each network user access to files and
other shared resources
• Groups
– Basis for resource and account management
– Assists in resource sharing and security control
• Example: network administrator for public elementary
school
Network+ Guide to Networks, 5th Edition
12
Users and Groups (cont’d.)
Table 9-1 Providing security through groups
Network+ Guide to Networks, 5th Edition
13
Users and Groups (cont’d.)
• Nesting or hierarchical group arrangement
– Simplifies management
– Group arrangement
• Affects permissions granted to each group’s members
• Inherited permissions
– Passed down from parent group to child group
• After user, group restrictions applied
– Client allowed to share network resources
Network+ Guide to Networks, 5th Edition
14
Identifying and Organizing Network
Elements
• Modern NOSs
– Similar patterns for organizing information
• Users, printers, servers, data files, and applications
• Directory
– List organizing resources
• Associates resources with characteristics
– Example: file system directory
Network+ Guide to Networks, 5th Edition
15
LDAP (Lightweight Directory Access
Protocol)
• Used to access information stored in directory
• Object
– Thing or person associated with network
• Attributes
– Properties associated with object
• Schema
– Set of definitions
– Kinds of objects and object-related information
contained in directory
Network+ Guide to Networks, 5th Edition
16
LDAP (cont’d.)
• Schema (cont’d.):
– Two types of definitions:
• Classes (object classes): identifies object type specified
in directory
• Attributes: stores information about object
Network+ Guide to Networks, 5th Edition
17
Figure 9-3 Schema elements associated
with a User account object
Network+ Guide to Networks, 5th Edition
18
LDAP (cont’d.)
• Containers (OUs or organizational units)
– Logically defined receptacles
• Assemble similar objects
– Account
• User record containing all properties
• LDAP standard
– Directories and contents form trees
– Tree
• Logical representation of multiple, hierarchical levels
within directory
• Root, branches, leafs
Network+ Guide to Networks, 5th Edition
19
Identifying and Organizing Network
Elements (cont’d.)
Figure 9-4 A directory tree
Network+ Guide to Networks, 5th Edition
20
LDAP (cont’d.)
• Before installing NOS
– Plan directory tree
• Consider current, future needs
• Book example
– New manufacturing firm: Circuits Now
Network+ Guide to Networks, 5th Edition
21
Identifying and Organizing Network
Elements (cont’d.)
Figure 9-5 Two possible directory trees for the same organization
Network+ Guide to Networks, 5th Edition
22
Sharing Applications
• Shared applications
– Often installed on file server
• Specifically designed to run applications
• Application licensing types
– Per user licensing
– Per seat licensing
– Site license
Network+ Guide to Networks, 5th Edition
23
Sharing Applications (cont’d.)
• Installing application on server
–
–
–
–
–
Purchase appropriate type and number of licenses
Verify server resources
Install application
Make application available
Provide users access to application
• NOS responsible for arbitrating file access
• Problem with shared file access
– Multiple users simultaneously accessing same data
files, same program files
Network+ Guide to Networks, 5th Edition
24
Sharing Printers
• Increases resource management efficiency; reduces
costs
• Print server
– Manages print services
• Printer attaches to print server
– Directly
– To convenient network location
• All NOSs perform common tasks in managing
printers
Network+ Guide to Networks, 5th Edition
25
Sharing Printers (cont’d.)
Figure 9-6 Shared printers on a network
Network+ Guide to Networks, 5th Edition
26
Sharing Printers (cont’d.)
• To create new printer
– Install printer driver
• Provides printer availability to users
– Ensure appropriate printer queue user rights
• Networked printers
– Appear as icons in Printers folder
• Client redirector
– Determines where print request should transmitted
• Network, workstation
Network+ Guide to Networks, 5th Edition
27
Managing System Resources
• Limited server system resources
– Required by multiple users
• Modern NOSs capabilities
– Maximize server memory, processor, bus, and hard
drive use
• Accommodates more client requests faster
• Improves overall network performance
Network+ Guide to Networks, 5th Edition
28
Memory
• Virtual memory can boost total memory available
• Physical memory: RAM chips
– Physical memory required by server varies
• Task dependent
• Virtual memory: stored on hard drive
– Page file (paging file, swap file)
• Managed by operating system
– Paging
• Moving blocks (pages) from RAM into virtual memory
Network+ Guide to Networks, 5th Edition
29
Memory (cont’d.)
• Virtual memory advantages
– Easily expands memory available to server
applications
– Engaged by default
• Virtual memory disadvantage
– Slows operations
• Hard drive access versus physical memory access
Network+ Guide to Networks, 5th Edition
30
Multitasking (cont’d.)
• Execution of multiple tasks at one time
– All operating system perform
• Does not mean performing more than one operation
simultaneously
• Preemptive multitasking (time sharing: UNIX)
– Happens quickly
– Appearance of tasks occurring simultaneously
Network+ Guide to Networks, 5th Edition
31
Multiprocessing (cont’d.)
• Process
– Routine of sequential instructions that runs until goal
is achieved
• Thread
– Self-contained; well-defined task within process
– Main thread
• All processes have one
• One processor systems
– One thread handled at any time
Network+ Guide to Networks, 5th Edition
32
Multiprocessing (cont’d.)
• Support use of multiple processors to handle
multiple threads
• Technique to improve response time
• Splits tasks among more than one processor
– Expedites single instruction completion
Network+ Guide to Networks, 5th Edition
33
Multiprocessing (cont’d.)
• Symmetric multiprocessing
– Splits all operations equally among two or more
processors
• Asymmetric multiprocessing
– Assigns each subtask to specific processor
• Multiprocessing advantage to servers with high
processor usage
– Numerous tasks simultaneously
Network+ Guide to Networks, 5th Edition
34
Windows Server 2008
• Released February 2008
• Enhancement of Windows Server 2003
• GUI (graphical user interface)
– Pictorial representation of computer function
– NOS GIUs
• Enable administrator to manage files, users, groups,
security, and printers
• Enhanced security, reliability, remote client support,
and performance
• New server management features
Network+ Guide to Networks, 5th Edition
35
Windows Server 2008 (cont’d.)
• Editions
–
–
–
–
Standard Edition
Web Edition
Enterprise Edition
Datacenter Edition
• Popular NOS
–
–
–
–
Address most network administrator’s needs well
Well-established vendor
Device; program compatibility
Larger market offers technical support
Network+ Guide to Networks, 5th Edition
36
Windows Server 2008 (cont’d.)
• General benefits
– Offers several general benefits
– Offers simple user interfaces
• Disadvantage
– Past criticism for performance, security
Network+ Guide to Networks, 5th Edition
37
Hardware Requirements
• Server components
– Processing power, memory, and hard drive space
• Windows Server Catalog
– Windows Server 2008 compatible computer
components
– Available online
– Consult it prior to hardware purchases
Network+ Guide to Networks, 5th Edition
38
Hardware Requirements (cont’d.)
Table 9-2 Minimum hardware requirements for Windows Server 2008, Standard
Edition
Network+ Guide to Networks, 5th Edition
39
Memory Model
• Addressing schemes
– 32-bit addressing scheme
– 64-bit addressing scheme
• Assigns each application (process)
– Own 32-bit memory area
• Logical subdivision memory available to server
• Important Windows Server 2008 feature
– Install more server physical memory
• Uses virtual memory
Network+ Guide to Networks, 5th Edition
40
Figure 9-7 The Windows Server 2008 Performance Options Advanced tab
Network+ Guide to Networks, 5th Edition
41
NTFS (New Technology File System)
• File system
– Methods of organizing, managing, and accessing files
• Through logical structures, software routines
• NTFS (New Technology File System)
– Installed by default
• Disk data distribution
– Disks divided into allocation units (clusters)
– Allocation units combine to form partition
• Logically separate hard disk storage area
Network+ Guide to Networks, 5th Edition
42
NTFS (cont’d.)
• Advantages
– Secure, reliable, and file compression
– Handles massive files
• Allow fast access to resources
– Used on all Windows operating system versions
• Since Windows NT
– Offers many features
• Drawback
– Cannot be read by older operating systems
Network+ Guide to Networks, 5th Edition
43
Active Directory
• Directory service
• Originally designed for Windows 2000 Server
– Enhanced with Windows Server 2008
• Windows Server 2008 network
– Workgroup model
– Domain model
Network+ Guide to Networks, 5th Edition
44
Workgroups
• Peer-to-peer network
• Decentralized management
– Each computer has own database
• User accounts, security privileges
– Significantly more administration effort
• Practical for small networks
– Few users
– Simple to design, implement
Network+ Guide to Networks, 5th Edition
45
Domains
• Group of users, servers, and other resources
– Share centralized account and security information
database
• Client/server network
• Active directory
– Contains domain databases
– Easier to organize and manage resources and
security
Network+ Guide to Networks, 5th Edition
46
Domains (cont’d.)
Figure 9-8 Multiple domains in one organization
Network+ Guide to Networks, 5th Edition
47
Domains (cont’d.)
• Domain not confined by geographical boundaries
• Domain controllers
– Contains directory containing information about
objects in domain
• Member servers
– Do not store directory information
• Replication
– Process of copying directory data to multiple domain
controllers
Network+ Guide to Networks, 5th Edition
48
Domains (cont’d.)
Figure 9-9 Domain model on a Windows Server 2008 network
Network+ Guide to Networks, 5th Edition
49
OUs (Organizational Units)
• Hold multiple objects having similar characteristics
– Can be nested
• Provides allows simpler, more flexible administration
Network+ Guide to Networks, 5th Edition
50
Trees and Forests
• Directory structure above domains
– Large organizations use multiple domains
• Domain tree
– Organizes multiple domains hierarchically
• Root domain
– Active Directory tree base
• Child domains
– Branch off from root domain
• Separate groups of objects with same policies
Network+ Guide to Networks, 5th Edition
51
Trees and Forests (cont’d.)
• Forest
– A collection of one or more domain trees
– Share common schema
• Domains within a forest can communicate
• Domains within same tree
– Share common Active Directory database
Network+ Guide to Networks, 5th Edition
52
Trees and Forests (cont’d.)
Figure 9-10 A tree with multiple domains and OUs
Network+ Guide to Networks, 5th Edition
53
Trust Relationships
• Relationship between two domains
– One domain allows another domain to authenticate its
users
• Active Directory supports two trust relationship types
– Two-way transitive trusts
– Explicit one-way trusts
Network+ Guide to Networks, 5th Edition
54
Trust Relationships (cont’d.)
Figure 9-11 Two-way trusts between domains in a tree
Network+ Guide to Networks, 5th Edition
55
Trust Relationships (cont’d.)
Figure 9-12 Explicit one-way trust between domains in different trees
Network+ Guide to Networks, 5th Edition
56
Naming Conventions
• Active Directory naming (addressing) conventions
– Based on LDAP naming
• Internet namespace
– Complete hierarchical names database
• Used to map IP addresses to hosts’ names
• Active Directory namespace
– Collection of object names, associated places in
Windows Server 2003, Server 2008 network
• Two namespaces are compatible
Network+ Guide to Networks, 5th Edition
57
Naming Conventions (cont’d.)
• Windows Server 2008 network object
– Three different names
• DN (distinguished name): DC (domain component) and
CN (common name)
• RDN (relative distinguished name)
• UPN (user principal name)
• GUID (globally unique identifier)
– 128-bit number
• Ensures no two objects have duplicate names
Network+ Guide to Networks, 5th Edition
58
Naming Conventions (cont’d.)
Figure 9-13 Distinguished name and relative distinguished name
Network+ Guide to Networks, 5th Edition
59
Server Management
• Setting up and managing server
– Choose role
• Reflects server’s primary purpose
– Conduct server management task
• Server Manager: GUI tool
• Many functions available
• Use Server Manager window
Network+ Guide to Networks, 5th Edition
60
Server Management (cont’d.)
Figure 9-14 Windows Server 2008 Server Manager
Network+ Guide to Networks, 5th Edition
61
Server Management (cont’d.)
Figure 9-15 Server Manager’s Reliability and Performance window
Network+ Guide to Networks, 5th Edition
62
UNIX and Linux
• Popular NOSs
– Provide resource sharing
– Older
• UNIX develop in 1969
• UNIX preceded, led to TCP/IP protocol suite
development
– Most Internet servers run UNIX
• Efficient and flexible
• Some difficulty to master UNIX
– Not controlled, distributed by single manufacturer
– Some version nonproprietary and freely distributed
Network+ Guide to Networks, 5th Edition
63
A Brief History of UNIX
• Late 1960s: UNIX operating system
• 1970s
– Antitrust laws and AT&T
– Anyone could purchase the source code
– New versions of UNIX appeared
• System V, BSD
• 1980s
– Rights changes hands, now owned by Novell
• Open Group owns UNIX trademark
Network+ Guide to Networks, 5th Edition
64
Varieties of UNIX
• Many varieties (flavors, distributions)
– Share several features
• UNIX operating system
– Divided into two main categories
• Proprietary
• Open source
Network+ Guide to Networks, 5th Edition
65
Proprietary UNIX
• Source code unavailable
• Available only by purchasing licensed copy from
Novell
• Vendors
– Apple Computer: Mac OS X Server
– Sun Microsystems: Solaris
– IBM: AIX
Network+ Guide to Networks, 5th Edition
66
Proprietary UNIX (cont’d.)
• Proprietary UNIX system advantages
– Accountability and support
– Optimization of hardware and software
– Predictability and compatibility
• Proprietary UNIX system drawback
– No source code access
• No customization
Network+ Guide to Networks, 5th Edition
67
Open Source UNIX
• Customizable
• Not owned by any one company
– No licensing fees
• Open source software (freely distributable software)
– UNIX GNU, BSD, and Linux
• Variety of implementations
• Run on wider range of systems
• Key difference from proprietary implementations
– Software license
Network+ Guide to Networks, 5th Edition
68
Two Flavors of UNIX
• Solaris
–
–
–
–
Sun Microsystems
Runs on SPARC-based servers
All commercially supported operating system benefits
Use: Runs intensive applications
• Examples: large, multiterabyte databases, weather
prediction systems, and large economic modeling
applications
• Linux follows standard UNIX conventions
– Highly stable, free
– Developed by Linus Torvalds (1991)
Network+ Guide to Networks, 5th Edition
69
Two Flavors of UNIX (cont’d.)
• All UNIX and Linux versions
– Offer host of features
•
•
•
•
TCP/IP protocol suite
Applications to support networking infrastructure
Support non-IP protocols
Programs necessary for routing, firewall protection,
DNS services, DHCP services
• Operates over many different network topologies,
physical media
• Efficiently and securely handle growth, change, stability
• Source code used, thoroughly debugged
Network+ Guide to Networks, 5th Edition
70
Hardware Requirements
• Similar to Windows Server 2003, Server 2008
– Key differences
• UNIX, Linux operating system can act as workstation or
server operating system
• GUI (graphical user interface) remains optional
• No single “right” server configuration exists
Network+ Guide to Networks, 5th Edition
71
Solaris Hardware Requirements
Table 9-3 Minimum hardware recommendations for Solaris 10
• Computers containing Sun SPARC processors or
Intel-based processors
Network+ Guide to Networks, 5th Edition
72
Linux Hardware Requirements
Table 9-4 Minimum hardware recommendations for a Linux server
• Linux servers adhere to certain minimum
requirements
Network+ Guide to Networks, 5th Edition
73
UNIX Multiprocessing
• UNIX and Linux
– Support processes and threads
– Allocate separate resources (memory space) to each
process
• When created
• Manage access to resources
• Advantage: prevents one program from disrupting
system
– Support symmetric multiprocessing
– Different versions support different number of
processors
Network+ Guide to Networks, 5th Edition
74
The UNIX Memory Model
• Use physical, virtual memory efficiently
• Allocate memory area for each application
– Share memory between programs when possible
• Use 32-bit addressing scheme
– Programs access 4 GB memory
• Most systems also run on CPUs employing 64-bit
addresses
– 18 exabytes (264 bytes) memory
• Virtual memory
– Disk partition or file
Network+ Guide to Networks, 5th Edition
75
The UNIX Kernel
• Kernel
– Core of all UNIX and Linux systems
• Kernel module
– File containing instructions for performing specific
task
• Reading data from and writing data to hard drive
Network+ Guide to Networks, 5th Edition
76
UNIX System File and Directory
Structure
• Hierarchical file system
– Disk directories may contain files, other directories
•
•
•
•
/boot directory: kernel, system initialization files
/sbin directory: applications, services
/var directory: variable data
/home directory: created for new users
Network+ Guide to Networks, 5th Edition
77
UNIX System File and Directory
Structure (cont’d.)
Figure 9-16 UNIX file system hierarchy
Network+ Guide to Networks, 5th Edition
78
UNIX File Systems
• Two broad categories
– Disk file systems
– Network file systems
Network+ Guide to Networks, 5th Edition
79
Disk File Systems
• Organizing, managing, accessing files
– Through logical structures, software routines
• Linux native file system type
– ext3: “third extended” file system
• Solaris native file system
– UFS (UNIX file system)
Network+ Guide to Networks, 5th Edition
80
Network File Systems
• Analogous to Windows shares
– Attach shared file systems (drives)
• From Windows, other UNIX servers
– Share files with users on other computers
• UNIX and Linux popular remote file system type
– Sun Microsystems’ NFS (Network File System)
• Open source application implementing Windows
SMB, CIFS file system protocols
– Samba
Network+ Guide to Networks, 5th Edition
81
A UNIX and Linux Command Sampler
• Many system administrators prefer command line
• GUI executes commands
– Responds to mouse clicks
• Command interpreter (shell)
– Accepts keyboard commands and runs them
• Man pages (manual pages)
– Full documentation of UNIX commands
– Nine sections
– apropos command
• Helps find possible man page entries
Network+ Guide to Networks, 5th Edition
82
A UNIX and Linux Command Sampler
(cont’d.)
• Commands function like sentences
• Rules guide UNIX command use
• Significant UNIX and Windows command-line
interface difference
– Character separating directories
• Windows separator character: ( \ )
• UNIX separator character: ( / )
Network+ Guide to Networks, 5th Edition
83
Table 9-5 Commonly used UNIX commands
Network+ Guide to Networks, 5th Edition
84
A UNIX and Linux Command Sampler
(cont’d.)
• Most frequently used UNIX command
– ls
– Provides file information
• Stores in file inode (information node)
– ls –l command
• Access permissions field
• Files type designations
• Pipe
– Direct one command output to input of another
command
– Unix: vertical bar ( | )
Network+ Guide to Networks, 5th Edition
85
Figure 9-17 Example of output from ls -l
Network+ Guide to Networks, 5th Edition
86
Figure 9-18 Anatomy of ls –l output
Network+ Guide to Networks, 5th Edition
87
Summary
• Characteristics common to all NOS
– Systems and servers, client support, identifying and
organizing network elements, sharing applications
and printers, managing system resources
• Windows Server 2008 network structure
• Unix and Linux concepts and features
Network+ Guide to Networks, 5th Edition
88