1. CONNECTING TO THE INTERNET
Chapter 5
CONNECTING TO THE INTERNET

2. Chapter 5: CONNECTING TO THE INTERNET
CHAPTER INTRODUCTION
List the types of routers used for Internet connections.
Describe the various WAN technologies used for Internet connections.
Understand the criteria used to select an ISP for a network Internet connection.
List the criteria for determining how much Internet bandwidth a network needs.
Determine the Internet access security requirements for a network.

3. UNDERSTANDING INTERNET CONNECTIVITY ARCHITECTURE
Chapter 5: CONNECTING TO THE INTERNET
UNDERSTANDING INTERNET CONNECTIVITY ARCHITECTURE

4. INTERNET ACCESS ROUTERS
Chapter 5: CONNECTING TO THE INTERNET
INTERNET ACCESS ROUTERS
Software
Windows Server 2003
Any Microsoft operating system that supports ICS
Any operating system that provides firewall capabilities
Hardware
Dedicated devices

5. INTERNET CONNECTION TYPES
Chapter 5: CONNECTING TO THE INTERNET
INTERNET CONNECTION TYPES
Dial-up modem
ISDN
CATV and DSL
Leased lines
Frame relay

6. DIAL-UP MODEM CONNECTIONS
Chapter 5: CONNECTING TO THE INTERNET
DIAL-UP MODEM CONNECTIONS
Maximum speed of 53 Kbps downstream, 33.6 Kbps upstream
Widely available
Requires standard phone line and modem
Inexpensive to implement and run

7. Chapter 5: CONNECTING TO THE INTERNET
ISDN
Dial-up technology
Requires specialized phone line and hardware
Available in two versions
BRI
128 Kbps
PRI
1.544 Mbps

8. Chapter 5: CONNECTING TO THE INTERNET
CATV AND DSL
CATV
Available from cable TV providers.
Bandwidth varies depending on location and other users.
DSL
Uses standard phone lines.
Consistent bandwidth.

9. Chapter 5: CONNECTING TO THE INTERNET
LEASED LINES
Always-on, high-speed digital connection
Requires special hardware, installation, and maintenance
Normally available in two variants
T-1 (also known as DS-1)
1.544 Mbps
T-3 (also known as DS-3)
Mbps

10. Chapter 5: CONNECTING TO THE INTERNET
FRAME RELAY
Still requires modem, leased line, or ISDN connection to ISP.
Allows you to more effectively manage ISP costs if they are charged on a usage basis.
Not all ISPs provide support for frame relay connections.

11. INTERNET SERVICE PROVIDERS
Chapter 5: CONNECTING TO THE INTERNET
INTERNET SERVICE PROVIDERS
Provide Internet access to business and residential customers
Provide related services such as web hosting, , and DNS server services
Organized into tiers depending on their proximity to the Internet backbone

12. UNDERSTANDING ISP SERVICES
Chapter 5: CONNECTING TO THE INTERNET
UNDERSTANDING ISP SERVICES
Multiple WAN support
IP addresses
DNS servers
services
Web hosting
Internet domain hosting

13. DETERMINING INTERNET CONNECTIVITY REQUIREMENTS
Chapter 5: CONNECTING TO THE INTERNET
DETERMINING INTERNET CONNECTIVITY REQUIREMENTS
How much bandwidth?
How many users?
What applications do the users need?
When is Internet bandwidth needed?
Where are the users located?

14. Chapter 5: CONNECTING TO THE INTERNET
HOW MUCH BANDWIDTH?
How many users will require Internet access at one time?
What applications will the users need?
When will the users need access to the Internet?
Where will the users be located?
How much incoming bandwidth will Internet servers require?

15. Chapter 5: CONNECTING TO THE INTERNET
HOW MANY USERS?
Not necessarily equivalent to the number of employees.
More accurate measure is how many computers, particularly in environments where computer systems may be shared.
Consider work habits such as employees working on a shift system.
Consider the type of Internet access required by different users.

16. WHAT APPLICATIONS DO THE USERS NEED?
Chapter 5: CONNECTING TO THE INTERNET
WHAT APPLICATIONS DO THE USERS NEED?
Some applications are more connection-intensive than others.
Consider implementing restrictions to limit the use of unauthorized or unnecessary applications.

17. WHEN IS INTERNET BANDWIDTH NEEDED?
Chapter 5: CONNECTING TO THE INTERNET
WHEN IS INTERNET BANDWIDTH NEEDED?
Daily schedule
Business model
Annual schedule

18. WHERE ARE THE USERS LOCATED?
Chapter 5: CONNECTING TO THE INTERNET
WHERE ARE THE USERS LOCATED?
Influences placement of Internet connectivity solutions
Can have an effect on IP addressing schemes
Can have an effect on features such as NAT

19. SECURING AND REGULATING INTERNET ACCESS
Chapter 5: CONNECTING TO THE INTERNET
SECURING AND REGULATING INTERNET ACCESS
Most companies monitor Internet access by employees.
Some companies regulate what employees can access on the Internet.
Threats include viruses, information theft, and loss of productivity.

20. DETERMINING INTERNET SECURITY REQUIREMENTS
Chapter 5: CONNECTING TO THE INTERNET
DETERMINING INTERNET SECURITY REQUIREMENTS
Limiting applications
Limiting users
Regulating Internet access

21. LIMITING APPLICATIONS
Chapter 5: CONNECTING TO THE INTERNET
LIMITING APPLICATIONS
Using unregistered IP addresses through a firewall protects systems on the internal network from being contacted by systems on the Internet.
Port filtering can be used to prevent users from accessing applications from servers based on the TCP/IP port number.
Packet filters allow you to control what applications are accessible through the firewall or proxy server.

22. Chapter 5: CONNECTING TO THE INTERNET
LIMITING USERS
Two commonly implemented methods of limiting Internet access by users:
Packet filtering
Authentication

23. REGULATING INTERNET ACCESS
Chapter 5: CONNECTING TO THE INTERNET
REGULATING INTERNET ACCESS
By using a software application like a proxy server, you can
Monitor what users are accessing on the Internet.
Identify excessive Internet use.
Block sites based on content.

24. USING NETWORK ADDRESS TRANSLATION
Chapter 5: CONNECTING TO THE INTERNET
USING NETWORK ADDRESS TRANSLATION
Static NAT
Provides one-to-one translation between unregistered and registered IP addresses
Dynamic NAT
Provides many-to-many translation between unregistered and registered IP addresses
Masquerading NAT
Provides many-to-one translation between unregistered and registered IP addresses

25. Chapter 5: CONNECTING TO THE INTERNET
NAT SECURITY
Relies on basic methods and procedures to provide security
Is not a substitute for a full-featured firewall
Does not provide the capability to block based on traffic type
Does not protect against denial of service (DoS) attacks

26. STATEFUL PACKET INSPECTION
Chapter 5: CONNECTING TO THE INTERNET
STATEFUL PACKET INSPECTION
Inspects the contents of each packet as it travels between interfaces running the stateful inspection software
Allows common threats to be identified and filtered
Provides ancillary services such as detailed logging

27. Chapter 5: CONNECTING TO THE INTERNET
PORT FORWARDING
Allows an internally hosted system to be accessed through NAT by an external system
Disguises the IP address of the internal system, which provides added security
Used to take advantage of features like load balancing and redirection

28. Chapter 5: CONNECTING TO THE INTERNET
USING A PROXY SERVER
Acts as an intermediary between client computers on a private network and servers on the Internet
Forwards all requests with the IP address of the proxy server external interface
Works only with specific client applications
Allows Internet access to be controlled and monitored

29. USING MICROSOFT INTERNET SECURITY AND ACCELERATION SERVER 2000
Chapter 5: CONNECTING TO THE INTERNET
USING MICROSOFT INTERNET SECURITY AND ACCELERATION SERVER 2000
Microsoft’s integrated proxy and firewall solution
Provides policy-based security
Requires users to authenticate before granting Internet access
Caches information retrieved from the Internet to improve performance

30. SELECTING AN INTERNET ACCESS METHOD
Chapter 5: CONNECTING TO THE INTERNET
SELECTING AN INTERNET ACCESS METHOD
NAT
Low security, low level of control
Proxy
High security, high level of control

31. Chapter 5: CONNECTING TO THE INTERNET
CHAPTER SUMMARY
Internet access routers can range from workstation computers to servers to dedicated hardware devices.
WAN technologies used to establish Internet connectivity include dial-up modems, ISDN, CATV, DSL, leased lines, and frame relay.
ISPs can provide a variety of services to business clients in addition to providing simple Internet access.
The Internet bandwidth needed by a network is based on the number of users and the types of applications they run.

32. CHAPTER SUMMARY (continued)
Chapter 5: CONNECTING TO THE INTERNET
CHAPTER SUMMARY (continued)
An Internet connection is a gateway that can work in both directions, enabling Internet users to access your private network as well as allowing your users Internet access.
Most NAT implementations today use masquerading, a technique that maps unregistered IP addresses to a single registered IP address combined with a port number.
Proxy server products have evolved to now include an array of firewall and access-control features that provide comprehensive Internet security for a private network.