Week 04 - NAT, Firewalls and Wireless Networks (L08-L10)

Question 1

What are the typical AP security precautions?

Answer 1

MAC, SSID, WEP/WPA, 802.1x

Question 2

What are the main risks of Wireless LANs?

Answer 2

• Rogue access points
• weak encryption

Question 3

Name three types of NAT?

Answer 3

• NAPT
• Destination NAT
• Static NAT

Question 4

Define Routing?

Answer 4

Routing is performed on Layer 3. Goal is to find the best path for a data packets from A to B.

Question 5

What frequencies do 802.11b and 802.11g operate at?

Answer 5

2.4 GHz

Question 6

What frequency is better for long distances or solid objects?

Answer 6

low frequenz, 2.4 GHz

Question 7

What are rogue access points?

Answer 7

Access points that do not belong to your network configuration. Unauthorized Access Point that is connected to the network.

Question 8

What is NAT? How does it work?

Answer 8

Network Address Translation. Multiple private IP addresses can use one public IP adress. Router does NAT. Translates priv. IP to public IP by mainting a NAT table

Question 9

Which standards share the same frequency?

Answer 9

b+g, a+n

Question 10

Name three types of firewall?

Answer 10

• Packet filter
• Proxy
• Application filter

Question 11

Which standard is best for areas with high user density?

Answer 11

802.11a, because operations in 5GHz, with multiple access points

Question 12

What is Round Trip Time?

Answer 12

Time need for a data packet to arrive at destination plus time sender receives acknoweldgment of reception.

Question 13

Explain the three WLAN topologies

Answer 13

Ad-Hoc: peer to peer connection between clients without management component

Infrastructure: More professional network setup. Wireless device connects to AP. AP enforces security via MAC, SSID, WEP/WPA or IEEE 802.1x (mutual authentication w/ radius server)

Bridge Mode: two networks together

Question 14

What is “Association” in infrastructure mode?

Answer 14

Establish connection and successful authentication on an Access Point

Question 15

What are firewalls?

Answer 15

Software and/or hardware componment that can control network flow.

Question 16

What are the common encryption methods in WLAN?

Answer 16

• WEP - Wired Equivalent Privacy (WEP)
• WPA - Wi-Fi Protected Access (TKIP)
• WPA2 - Wi-Fi Protected Access 2 (AES)

Question 17

What or the benefits of WLAN?

Answer 17

• easy to setup
• low cost
• scalable
• good for old buildings
• backup for wired network

Question 18

What are the limitation of NAT?

Answer 18

VPN, Requests from outside, some services do not support NAT

Question 19

Explain the architecture types of firewalls?

Answer 19

• Dual Home
• Screened Host
• Screened subnet

Question 20

Define Bandwidth and Latency, and how they are measured.

Answer 20

Bandwidth: speed or throughput when sending data. Meassured in bits per seconds

Latency: Time data packets need from a to be. Meassured in miliseconds

Question 21

Explain the 802.1x mechanism

Answer 21

Mutual authentication between client and network. In four steps: 1: client sends autentication request to AP, 2: AP forwards request to LAN switch, 3: LAN switch makes authentication with RADIUS server, 4: if OK, four way key negotation of session key between switch and client

Question 22

What are other uses of NAT?

Answer 22

• Load balancing
• Transparent Proxy
• Failover
• Overlapping networks