Client/ Server technologies and
their applications
Introduction
to Networking
Networks
Defined
• 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
Mainframe
Terminal
Terminal
Terminal
Terminal
Client/Server
Model
• The client/server model database example
– SQL
• Client/server advantages
• Migration to client/server architecture
– Workstations
Client/Server
Networking Model
Web-Based
Networking
• Advantages
– Mainframe model power
– Client/server model scalability
– Open, global solution
Networking
Categories
• Peer-to-peer
• Server-based
Network
Operating Systems
• Interoperability
– Novell NetWare
– Microsoft Windows
– UNIX
Networking
Protocols
OSI (International Organization for
Standardization)
Model Layers
Client
Server
Packet
Structure
TCP/IP
• A collection of protocols
– TCP
– IP
– An open standard
Additional
Networking Protocols
• NetBEUI
– NetBIOS
• AppleTalk
LANs and WANs
Local Area
Networks (LANs)
• A group of computers connected within a
confined geographic area
• Commonly used for intraoffice communication
Wide Area
Networks (WANs)
• A group of computers connected over
an expansive geographic area
Network
Access Points (NAPs)
• Internet backbones
• Backbone Network
Service
• Segments
New York
Backbone
Atlanta
Boston
Chicago
Phoenix
Backbone
Seattle
San
Francisco
Common
Network Components
IEEE
LAN 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
Additional
LAN Standards
• Apple LocalTalk
• FDDI
T-Carrier
System
T-Carrier
Data Transfer Rate
T1
1.544 Mbps
T2
6.312 Mbps
T3
44.736 Mbps
T4
274.176 Mbps
E-Carrier
System
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 Suite
and Internet Addressing
Internet
Architecture
Routing
Protocols
Port
Numbers
• Well-known port numbers
• Registered port numbers
Internet
Addressing
field1.
field2.field3.field4
Each field represents one byte of data
Reserved
IP 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/IP
Desktop Configurations
• Basic configurations
• Name resolution configurations
Diagnostic Tools
for Internet Troubleshooting
•
•
•
•
•
•
The ping command
The tracert command
The netstat command
The ipconfig command—Windows NT/2000
The arp command
Network analyzers
Internetworking Servers
Internetworking
Servers
•
•
•
•
•
•
•
File and print
HTTP
Proxy
Caching
Mail
Mailing list
Media
•
•
•
•
•
•
•
DNS
FTP
News
Certificate
Directory
Catalog
Transaction
File and
Print Servers
• File servers
• Print servers
– Print queue
– LPR/LPD
HTTP
Server Essentials
•
•
•
•
Web server
Web gateways
Additional HTTP server considerations
Common Web servers
Proxy
Servers
•
•
•
•
•
•
Caching Web documents
Providing corporate firewall access
Filtering client transactions
Logging transactions
Securing the host
Enabling enhanced administration
Caching
Servers
• Dedicated servers that speed data access by
storing data retrieved by users, then
presenting it directly to users
Mail
Servers
•
•
•
•
SMTP
POP
IMAP
POP3
Mailing
List Servers
• Mailing List Manager
• Public and private mailing lists
• Mailing list server vendors
Media
Servers
• Streaming audio and video
• Buffers
DNS
Servers
•
•
•
•
•
Hosts file
DNS hierarchy
DNS components
DNS server types
DNS records
FTP
Servers
• Logging control
• Access control
News
Servers
• Newsgroup issues
– Policies
– Security
– Legalities
Certificate
Servers
• Keys
• Identity theft
• Digital certificates
Directory
Servers
• Directory service uses
• Directory services protocols
Mirrored
Servers
• 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 Scripting
and Database Connectivity
Client-Side and
Server-Side Scripting
• Server-side includes
• Active content
HTTP
Gateways
•
•
•
•
Application program interface (API)
Client-side scripting
Load distribution
Transactions and download time
HTML Forms
and Form Processing
• <FORM> tag attributes
– METHOD attribute
– ACTION attribute
Common
Gateway 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-Tier
Computing Architecture
Data
Data
Data
Data
Mainframe
Minicomputer
Three-Tier
Computing Architecture
First Tier
Second (Middle)
Tier
Third Tier
Database
PC
Server
N-Tier
Computing Architecture
Second
(Middle) Tier
First Tier
Third Tier
Database
PC
Server
Server
Server
Database
Connectivity
• 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
The
Hacker Process
• Stage 1: Discovery
• Stage 2: Penetration
• Stage 3: Control
Defeating
Attacks
• 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
So slow connection?
(Secure sockets layer)
Virtual
Private Networks
•
•
•
•
•
•
Tunneling protocols
Encryption occurs  Source
Decryption occurs  Destination
VPN using PPTP
VPN using L2TP
VPN using ISAKMP or IPSec
Firewalls
Packet
Filters
• Packet fields
– Source IP address
– Destination IP address
– TCP/UDP source port
– TCP/UDP destination port
Proxy
Servers
• Circuit-level gateways
• Application-level gateways
Firewall
Topology
• Firewall implementations
– Packet filter
– Single-homed bastion host
– Dual-homed bastion host
– Screened subnet