Network Security

Question 1

Define the terms LAN, WAN and MAN.

Answer 1

LAN - Local control, small, can be physically protected
WAN - Controlled by single organisation, larger distance, physically exposed
MAN - Covering a city or metropolitan area. Similar to WAN

Question 2

Name four different types of topologies.

Answer 2

• Bus
• Ring
• Star
• Fully connected

Question 3

List four potential problems with networking.

Answer 3

• Resource sharing
• Network complexity
• Attacker anonymity
• Many points of access/unknown access path

Question 4

What is the simplest method of protecting a LAN?

Answer 4

Do not connect it to the internet. However, this isn’t always practical so a firewall should be used.

Question 5

What are the functions of a firewall?

Answer 5

• Access control in both direction
• Virus Checking
• Statistical
• Masking the structure of the LAN to the outside world

A firewall should be constant, tamperproof, and simple.

Question 6

What is packet filtering? How can the access be controlled?

Answer 6

Packet filtering is based on a series of riles blocking the flow of data to certain machine addresses and sources.

Access can be controlled by;

• Source address
• Destination
• Service requirement
• Local or outside IP Address

Question 7

What is stateful inspection?

Answer 7

Stateful inspection means checking for characteristics of a small section of a packet against a database of accepted/banned actions.
Faster than scanning the whole packet.

Question 8

HTTP, FTP, UDP, SMTP and SNMP are all ports/protocols. What do the stand for?

Answer 8

HTTP: hyper text transfer protocol 
FTP: file transfer protocol
UDP: user datagram protocol
SMTP: simple mail transport protocol
SNMP: simple network management protocol

Question 9

Firewalls are usually a special dedicated version of the following physical devices; router and gateway. What is a router and a gateway?

Answer 9

Router - a device that sends packets of information to the required destination. Internal messages can be sent directly whereas external messages are forwarded onwards.

Gateway - performs more substantial transforms on the packets (including modifications, mapping and encryption)

Both can be either hardware or software