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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