Page 143 - StudyBook.pdf

Communication Security: Remote Access and Messaging • Chapter 3 127

Figure 3.9 Providing Credentials for Logon

L2TP

As with TACACS+, Cisco believed they could design a better tunneling protocol,
which was the creation of the Layer 2 Forwarding (L2F ) protocol. Unfortunately,
L2F was not much better than PPTP. Specifically, L2F provided encapsulation (tun-
neling) but it did not encrypt the data being encapsulated.
To use the features of both PPTP and L2F, L2TP was developed through a
joint venture between Microsoft and Cisco. L2TP was a major improvement, but
still did not offer encryption.To remedy this, L2TP was designed to use IPSec for
encryption purposes.The differences between PPTP and L2TP that you need to
know for the Security+ exam are:

■ L2TP requires IPSec in order to offer encryption.

■ L2TP is often implemented as a hardware solution (though also available
on Windows RAS servers), where PPTP is not.

■ L2TP can run on top of protocols such as IP, Internetwork Packet
Exchange (IPX), and Systems Network Architecture (SNA), where PPTP
can work only on IP networks.

■ Using L2TP with IPSec provides per-packet data origin authentication
(proof that the data was sent by an authorized user), data integrity (proof

www.syngress.com