Homework 3.2

Clients Hub

Hub

Hub

Hub

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Client and Server Systems

• Operating Systems– Windows 95/98– Windows NT Workstation– Windows NT Server

• Centralized Security and system policies

• Telecommunications– Fax, mail, web

Network Servers

• Network Operating Systems– Timesharing: splitting time between jobs– Multitasking: processing more that one job at a

time– Parallel Processing: more than one cpu

processing jobs– Load Balancing: sending jobs to different

servers

Multitasking

• Preemptive– OS can take over a task without cooperation of

the task.

• Nonpreemptive– The task decides if it will give up the processor.

Dedicated vs. Nondedicated

• Dedicated Server– Server does server tasks only, it does not

execute local programs (Novell)– CPU time is dedicated to server operations

• Non Dedicated Server– The user has an interface to the OS on the

server and can execute programs locally (Linux, Microsoft)

Software Components

• Client– File access, Printing, Database access

• Server– Disks, Printers, Programs

• Redirectors– Handles client requests

• Forwards a local request to LPT1: to print server• Accesses non local drive letters: F:\>, G:\>, etc

Server Software

• Resource Sharing– File access: remote access to servers disks– Printer access: remote requests to local printer– Security and control

• Which users can access the disk or printer?• Which users can write to the disk?• File locking when 2 users want to write to the same

file.• Account for disk usage and printer paper

Server Administration

• Managing Users– Privileges

• Access to resources

• Passwords

– Location of users (address, email, etc.)– Time limits (8:00 AM to 5:00 PM)– Station limits (specific MAC address)

• Resource load balancing

Novell Operating Systems

• NetWare– NDS (Novell Directory Services)

• Disk caching and distribution among servers

– NDPS (Novell Distributed Printing Services)

– Web Servers

– Mail Services

– Calendaring/Scheduling

– Messenger service

– Routing

Novell File Services

• Logon Security– Authentication

• Trustee Rights– Who can access what file/directory and what

can they do with the file

• Directory attributes– The types of operations on a file (read, write,

shareable, copyable)

Novell Distributed Printing Services

• Print spooling and control– Access by users to specific printers– Print load is transferred from client to server– Printer messages (out of paper, change form)

are displayed on the server console.– Server handles multivendor printing protocols

so client doesn’t need to.– Clients can share their printer through the

server

Microsoft Network Operating Systems

• Windows NT (includes Win2000, XP)– Single domain, single server, small workgroup– Single master, single server, multiple

workgroups– Multiple master, multiple servers, several

workgroups, accounts on multiple servers– Complete Trust

• Several domains no master (workgroups trust each other)

Windows NT Services

• File services– Similar to Novell, access, control, rights– Security, server maintains access lists

• Printing– Clients or servers can share their local printers

• Routing and Remote access• Other services

– Messenger, Alerter, Browser

Interoperability

• Gateway Services for NetWare– Handles NetWare requests for a domain

• Client Services for NetWare– Handles NetWare requests for a workstation

• File and Print Services for NetWare– Protocol converter

• Directory Service Manager for NetWare– Allows Windows clients to access NDS

• Services for Macintosh– Allows Appletalk service on the NT server

Appletalk Networks

• Appleshare– Apple disk and printer sharing (Apple has it’s

own file formats)– Zones (Apple’s workgroups/domains)– Security (each client maintains it’s own lists)– Appletalk servers can handle multiple protocols

(TCP/IP, Appletalk, Microsoft)

UNIX (and Linux) Networks

• Simple Client only to Server transformation

• Can handle multiple protocols and services (Apple, Microsoft SMB, NFS)

• Can be configured as a router/firewall

• Well adapted to remote access

Peer to Peer

• Simple to set up (almost all OS’s have built in peer to peer support)

• Access lists are kept on each computer, there is no master server.

• Useful for small (10 or less) workstations

• Somewhat insecure

Interoperability

• Multivendor environments– Servers can support different OS clients– Files transferred from different server types go through the

client– Files transferred from different client OS’s go through the

server– File formats may be different on each vendors operating

system. File type conversion can be done on the server or client.

– Authentication is almost always different between vendors.– Network Protocols may also be different between vendors

Server Security

• Warnings:– When a server is placed on the network it is now wide

open for attack.

– All Network Operating Systems have bugs and security holes.

– Always upgrade to the latest revisions of the OS

– Limit the number of services provided by the server to the minimum needed for your particular application

– Use firewalls as needed in the local area network

Network Types

• What Protocol to use?– IPX– TCP/IP– Netbeui

• Which Name Service?– DNS– WINS– LMHOSTS

Windows NT/95/98/2K Client

• Pick a name (15 characters NetBios limit)– Or use WINS

• Pick a workgroup or domain• Get networking working• Add appropriate protocols• Edit LMHOSTS (for TCP/IP)• Use Network Neighborhood or Find

Computer to find the server

Workgroup/Domain

• Workgroup– Login is on each client– Simple, minimal security– No dedicated server

• Domain– Login is to the server over the network – Requires an NT Domain Server– High security, centralized usernames/passwords

Accessing Server Resources

• Nbtstat to check netbios connectivity

• UNC– universal naming convention– \\ntserver\users– \\ntserver\laser_office

• net use– net use j: \\opie\bobw– net use lpt1: \\ntserver\laser_office

Web Services

• Web Server (IIS on NT based systems)

• Security Issues– File access– Database access– CGI programs

• Counters

• Data Entry

Mail Services

• SMTP Support• POP and IMAP mail support• Novell Groupwise

– Calendaring– Scheduling

• Microsoft Exchange– Calendaring– Scheduling

Other Services

• DATABASE Support– Microsoft SQL Support– Oracle Support– MySQL Support

• Distributed License Service• Accounting of server and resource use

– Disk space– Pages printed