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156 Chapter 3 • Communication Security: Remote Access and Messaging

Summary of Security+ Exam Objectives

Secure communications are a necessity in today’s world, and there are many tools
available to users to protect information and networks from being compromised.
Knowing how these tools work and how certain tools differ from other tools
should be your goal when studying for the Security+ exam.

Remote Access Security

Although technology has made huge strides in remote access security, there are still
many problems.Technologies such as RAS servers, NAS,VPN, authentication
servers like RADIUS,TACACS, and TACACS+, and others were designed to
address these problems.
It is the security professional’s responsibility to ensure that everything possible
has been done to secure their networks. Security professionals have to find the bal-
ance between offering users the ability to work from remote locations, and
ensuring that the network is protected.The 802.1x standard is used for securing the
transfer of messages between a user and an access point.When a wireless user (or
supplicant) wants to access a wireless network, 802.1x forces them to authenticate
to a centralized authority called an authenticator. 802.1x uses the Extensible
Authentication Protocol (EAP) for passing messages between the supplicant and
the authenticator.The authenticator sends a request to the user requesting their
identity.The client returns their identity to the authenticator, which is forwarded to
an authentication server for verification.
VPNs use secure tunnels to allow remote users to connect to a network.VPNs
can be configured in two forms: site-to-site VPNs or remote access VPNs.VPNs
use IPSec, PPTP, or L2TP as the tunneling protocol.A tunnel is created by wrap-
ping (or encapsulating) a data packet inside another packet and transmitting it over
a public medium. PPTP is a Layer 2 (Data Link Layer) encapsulation (tunneling)
protocol using port 1723 and TCP for its transport protocol. L2TP is also a Layer 2
encapsulation protocol, but uses port 1701 and UDP. IPSec utilizes one of two pro-
tocols:AH or ESP in one of two modes—transport mode or tunnel mode. IPSec is
“a framework of open standards for ensuring private, secure communications over
IP networks, through the use of cryptographic security services.”
IPSec can be implemented in either tunnel mode or transport mode. IPSec uses
IKE to manage keys and authenticate the two ends of a secure tunnel before IPSec
transmissions begin. IPSec is made up of two separate security protocols: the (AH)
and the ESP. IPSec offers nonrepudiation through the use of digital signatures.A

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