12.6 VPNs

Question 1

What are the two primary categories of VPNs?

Answer 1

Site-to-site and client-to-site

Question 2

IPSec

Answer 2

IP Security

Question 3

GRE

Answer 3

Generic routing encapsulation

Question 4

L2TP

Answer 4

Layer 2 Transport Protocol, A VPN protocol that lacks security features, such as encryption and operates at Layer 2.

Question 5

L2F

Answer 5

Layer 2 forwarding, A VPN protocol designed with the intent of providing a tunneling protocol for PPP.

Question 6

IPSec VPNs offers what type of protection?

Answer 6

Confidentiality, integrity, and authentication.

Question 7

IPSec operates at what layer?

Answer 7

3

Question 8

IKE +

Answer 8

Internet Key Exchange. IPSec can provide encryption between authenticated peers using encryption keys, which are periodically changed. IKE, however, allows an administrator to manually configure keys.

Question 9

What are the three modes of operation that IKE can use?

Answer 9

Main mode (involves three exchanges of info), aggressive mode, quick mode.

Question 10

PFS +

Answer 10

Perfect forward secrecy, makes sure that a session key remains secure.

Question 11

ISAKMP

Answer 11

Internet security association and key management protocol

Question 12

SA

Answer 12

Security association

Question 13

IPSec relies on either the _____ protocol (IP protocol number 51) or the _____ protocol (IP protocol number 50)

Answer 13

Authentication Header AH, Encapsulating Security Payload ESP

Question 14

What is the main distinction between AH and ESP?

Answer 14

ESP encrypts the original packet, while AH does not offer encryption

Question 15

What does the GRE tunneling Protocol do?

Answer 15

The original IP packet is encapsulated inside of a GRE tunnel packet, which adds a new GRE tunnel header. The GRE packet is then sent over an IPSec tunnel. Even if the IPSec tunnel were running in transport mode, the original packet’s IP header would still not be visible. Instead, the GRE packet’s header would be visible.

Question 16

Ah and ESP operate in one of two modes:

Answer 16

Transport or tunnel mode

Question 17

SSL +

Answer 17

Secure socket layer provides cryptography and reliability for upper layers (Layers 5–7) of the OSI model.

Question 18

PPTP

Answer 18

Point-to-Point Tunneling Protocol (PPTP) is an older VPN protocol (which supported the dial-up networking feature in older versions of Microsoft Windows)

Question 19

TLS +

Answer 19

Transport Layer Security (TLS) has largely replaced SSL as the VPN protocol of choice for providing cryptography and reliability to upper layers of the OSI model.