Client/ Server technologies and their applications

Introductionto Networking

NetworksDefined

• Two or more connected computers that share data

• Network evolution– Centralized (mainframe) models– Client/server models– Web-based networking

Mainframes

• Retrieving information from mainframes• Mainframe liabilities• The future of mainframes

Mainframe Networking Model

Client/ServerModel

• The client/server model database example– SQL

• Client/server advantages• Migration to client/server architecture

– Workstations

Client/ServerNetworking Model

Web-BasedNetworking

• Advantages– Mainframe model power– Client/server model scalability– Open, global solution

NetworkingCategories

• Peer-to-peer• Server-based

NetworkOperating Systems

• Interoperability– Novell NetWare– Microsoft Windows – UNIX

NetworkingProtocols

OSI (International Organization for Standardization)

Model Layers

Application

Presentation

Session

Transport

Network

Data Link

Physical

Application

Presentation

Session

Transport

Network

Data Link

Physical

Client Server

PacketStructure

Trailer

Data

Header

TCP/IP

• A collection of protocols– TCP– IP– An open standard

AdditionalNetworking Protocols

• NetBEUI– NetBIOS

• AppleTalk

LANs and WANs

Local AreaNetworks (LANs)

• A group of computers connected within a confined geographic area

• Commonly used for intraoffice communication

Wide AreaNetworks (WANs)

• A group of computers connected over an expansive geographic area

NetworkAccess Points (NAPs)

• Internet backbones• Backbone Network

Service• Segments Atlanta

New York

Chicago

SanFrancisco

Boston

Phoenix

Seattle

Backbone

Backbone

CommonNetwork Components

IEEELAN Standards

• IEEE 802.2• Ethernet/IEEE 802.3• IEEE 802.3u—fast Ethernet• IEEE 802.3z and 802.3ab—gigabit Ethernet• IEEE 802.5—token ring• IEEE 802-12—100VG-AnyLAN

AdditionalLAN Standards

• Apple LocalTalk• FDDI

T-CarrierSystem

T-Carrier Data Transfer Rate

T1 1.544 Mbps

T2 6.312 Mbps

T3 44.736 Mbps

T4 274.176 Mbps

E-CarrierSystem

E-Carrier Data Transfer Rate

E1 2.048 Mbps

E2 8.448 Mbps

E3 34.368 Mbps

E4 139.264 Mbps

E5 565.148 Mbps

TCP/IP Suiteand Internet Addressing

InternetArchitecture

RoutingProtocols

PortNumbers

• Well-known port numbers• Registered port numbers

InternetAddressing

field1.field2.field3.field4

Each field represents one byte of data

ReservedIP Addressing

• 10.0.0.0 10.255.255.255• 172.16.0.0 172.31.255.255• 192.168.0.0 192.168.255.255

Subnet Masks

• Distinguish the network and host portions of an IP address

• Specify whether a destination address is local or remote

Normal TCP/IPDesktop Configurations

• Basic configurations• Name resolution configurations

Diagnostic Toolsfor Internet Troubleshooting

• The ping command• The tracert command• The netstat command• The ipconfig command—Windows NT/2000• The arp command• Network analyzers

Internetworking Servers

InternetworkingServers

• File and print• HTTP• Proxy• Caching• Mail• Mailing list• Media

• DNS• FTP• News• Certificate• Directory• Catalog• Transaction

File andPrint Servers

• File servers• Print servers

– Print queue– LPR/LPD

HTTPServer Essentials

• Web server• Web gateways• Additional HTTP server considerations• Common Web servers

ProxyServers

• Caching Web documents• Providing corporate firewall access• Filtering client transactions• Logging transactions• Securing the host• Enabling enhanced administration

CachingServers

• Dedicated servers that speed data access by storing data retrieved by users, then presenting it directly to users

MailServers

• SMTP• POP• IMAP• POP3

MailingList Servers

• Mailing List Manager• Public and private mailing lists• Mailing list server vendors

MediaServers

• Streaming audio and video• Buffers

DNSServers

• Hosts file• DNS hierarchy• DNS components• DNS server types• DNS records

FTPServers

• Logging control• Access control

NewsServers

• Newsgroup issues– Policies– Security– Legalities

CertificateServers

• Keys• Identity theft• Digital certificates

DirectoryServers

• Directory service uses• Directory services protocols

MirroredServers

• Mirror set• Redundant Array of Inexpensive Disks

standard

Choosing the Ideal Server

• Popular server products– Apache Web server– Microsoft IIS– Lotus Domino series– Sun-Netscape Alliance servers

Server-Side Scriptingand Database Connectivity

Client-Side andServer-Side Scripting

• Server-side includes• Active content

HTTPGateways

• Application program interface (API)• Client-side scripting• Load distribution• Transactions and download time

HTML Formsand Form Processing

• <FORM> tag attributes– METHOD attribute– ACTION attribute

CommonGateway Interface

• Where are CGI scripts located?• Benefits

– Interpreted languages• Drawbacks

– Out-of-process events

CGI Alternatives: Server Programming Interfaces

• SAPI• ISAPI

– DLL files• NSAPI

CGI Alternatives:Scripting Technologies

• JSP• PHP• ASP• SSJS

CGI Alternatives:Java Servlets

• Java essentials• JVM• Java servlets versus scripting languages

Databases

• Online Transaction Processing• Types

– Nonrelational– Relational– Object-oriented

• Common features of a DBMS, RDBMS or ODBMS– Hierarchical versus network– One-tier, two-tier, three-tier and n-tier

Two-TierComputing Architecture

Three-TierComputing Architecture

PC

Database

Server

First TierSecond (Middle)

TierThird Tier

N-TierComputing Architecture

DatabaseConnectivity

• ODBC– 16-bit versus 32-bit– Registering a database

• JDBC

Database Connectivity Implementations

• Server-Side JavaScript and LiveWire• ColdFusion• Save as HTML• ASP and ActiveX Data Objects

Network Security Essentials

Defining

• Local resources• Network resources• Server resources• Database and information resources

Security Threats

• Accidental threats• Intentional threats

Viruses

• Types– Macros– Executables– Boot sector– Stealth– Polymorphic

• Virus protection software• User education

TheHacker Process

• Stage 1: Discovery• Stage 2: Penetration• Stage 3: Control

DefeatingAttacks

• OSI/RM security services– Authentication– Access control– Data confidentiality– Data integrity– Nonrepudiation

Auditing

• Status quo analysis• Risk analysis• Threat analysis

Authentication

• Proving what you know• Proving what you have• Proving who you are

Encryption

• Symmetric-key encryption– Symmetric algorithms– Dictionary programs– Password sniffing– SSL

• Asymmetric-key encryption

SSL

(Secure sockets layer)

So slow connection?

VirtualPrivate Networks

• Tunneling protocols• Encryption occurs Source• Decryption occurs Destination• VPN using PPTP• VPN using L2TP• VPN using ISAKMP or IPSec

Firewalls

PacketFilters

• Packet fields– Source IP address– Destination IP address– TCP/UDP source port– TCP/UDP destination port

ProxyServers

• Circuit-level gateways• Application-level gateways

FirewallTopology

• Firewall implementations– Packet filter– Single-homed bastion host– Dual-homed bastion host– Screened subnet