1. Network Security Marshall Leitem 11/30/04
Firewalls
Network Security
Marshall Leitem
11/30/04

2. Overview What is a firewall? What does it protect us from?
What does it consist of?
Hardware/software
Questions?

3. What is a Firewall? fire·wall
Any of a number of security schemes that prevent unauthorized users from gaining access to a computer network or that monitor transfers of information to and from the network.

4. Securities Employed Packet Filtering
Checks incoming packets to see they meet set requirements, if not the packets are discarded.
Proxy Service
Information from the Internet is retrieved by the firewall and then sent to the requesting system and vice versa.
Stateful inspection - doesn't examine the contents of each packet, compares certain key parts of the packet to a database of trusted information. Information traveling from inside the firewall to the outside is monitored for specific defining characteristics, then incoming information is compared to these characteristics. If the comparison yields a reasonable match, the information is allowed through. Otherwise it is discarded

5. What does it consist of? Software Implementations
Zone Alarm
Omniquad Personal Firewall
Norton Personal Firewall
Hardware Implementations
Linksys Etherfast Cable/DSL Firewall Router
CISCO PIX 500 Firewall

6. Pictures

7. Basic Topology

8. Examples of Common Filters
IP Address – has the ability to block specific IP’s or Domains or only permit specific ones.
Domains – can block access to specific domains or only allow specific domains
Protocols
Ports
Key Words

9. What it Prevents Remote Login Application Backdoors
SMTP session Jacking
Denial of Service Attacks
Spam
Source Routing

10. Demilitarized Zone
You want the un-trusted or un-known networks to have access to some of your resources
You still want to maintain a secure private network
A Firewall is used to create this area

11. DMZ(demilitarized zone)

12. DMZ

13. Downside of Firewalls Performance Degradation
Can be difficult to configure
Can be susceptible to IP-Spoofing
Can Interfere with some software
Extra Costs

14. Benefits of Firewalls
Provides a “choke point” in which traffic can be evaluated to see it meets specifications.
Prevents Remote Login
Allows rules on users and data traveling through to be imposed.

15. What can’t Firewalls Protect Against? (Steel door on a Wooden House)
Attacks that don’t go through firewall
Traitors
Manually Moving of Data (tape storage, etc)
Tunneling
Trojans & Viruses

16. Cost Options? Free – software based firewalls can be found
Exspensive up to $100,000+ hardware solutions that require much time and effort to install

17. Hardware Vs. Software Hardware
in most cases, they can be effective with little or no configuration
can protect every machine on a local network
Can be susceptible to attacks from inside the private network due to trojans
Often packet filtering is set up too trusting of outgoing packets
Group wide Policy

18. Hardware Vs. Software Software
you can specify which applications are allowed to communicate over the Internet from that PC (ex: only outlook express can use Port 25)
can only protect the machine they're installed on
Better protection against trojans and worms than hardware but must be configured on each machine

19. Questions?