Chapter 6 Questions 7 & 8

[Mike J Nagle]

7. What special function does a cache server perform? Why is this
useful for larger organizations?

A cache server is a proxy server that stores the most recently
accesses webpages in its internal cache. The proxy server is setup to
be in the DMZ or another unsecured area where it is exposed directly
to the internet so that the actual web server can be placed in a
secured area. Thus the relatively-less-important cache server exposed
to threats from the internet, protecting the more valuable web server.
Also, additional filtering routers can be placed between the proxy
server and the web server, increasing the protection for the latter.


8. Describe how the various types of firewalls interact with the
network traffic at various levels of the OSI model.

Proxy Server: also known as an Application-Level Firewall, is used to
filter packets in a specific protocol, such as FTP, SMTP, or HTTP.
This falls in the Application, Presentation, or Session layer of the
OSI model.

Circuit Gateway Firewall: this operates at the Transport Level of the
OSI model. The Circuit Gateway allows connection only between certain
specific networks, without specifically filte4ring any data packets.

Packet-Filtering Firewall: Allows the passage of only certain packets
between networks. They operate at the Network Level of OSI.

MAC Layer Firewall: Operate at the Media Access Control sub-layer of
the Datalink layer of the OSI. Packets are filtered according to ACL
entries that are assigned to computers according to their MAC
addresses.

[Elma Hartunian]

NIce job on both.

 

 

8. Describe how the various types of firewalls interact with the network traffic at various levels of the OSI model.

Packet filtering firewalls scan network data packets looking for compliance with or violation of the rules of the firewall’s database. Filtering firewalls inspect packets at the network layer, or Layer 3, of the OSI model. MAC layer firewalls are designed to operate at the media access control layer (layer 2) of the OSI network mode. Application level firewalls will operate at OSI layers above layer 3, using specific knowledge of various protocols and applications to make more informed decisions about packet forwarding.

 

9. What is a hybrid firewall?

A hybrid is a firewall that combines features and functions from other types of firewalls. Hybrid firewalls use a combination of the other three methods, and in practice, most firewalls fall into this category, since most use multiple approaches within the same device.