Wi-Fi Protected Access
(WPA) − This protocol implements the majority of the
IEEE 802.11i standard. It existed before IEEE 802.11i and uses RC4 algorithm
for encryption. It has two modes of operation. In ‘Enterprise’ mode, WPA uses
authentication protocol 802.1x to communicate with authentication server, and
hence pre-
master keys (PMK) is specific to client station. In ‘Personal’ mode,
it does not use 802.1x, PMK is replaced by a pre-shared key, as used for Small
Office Home Office (SOHO) wireless LAN environments.
WPA also includes a sound message integrity check replacing the Cyclic
Redundancy Check (CRC) that was used by the WEP standard.
WPA2
− WPA2 replaced the WPA. WPA2 implements all mandatory elements
of IEEE 802.11i scheme. In particular, it includes mandatory support for
CCMP, an AES-based encryption mode with strong security. Thus, as far as
the attacks are concerned, WPA2 / IEEE802.11i provides adequate solutions
to defend against WEP weaknesses, man-in-the-middle attacks, forgery
packets forgery, and replay attacks. However, DoS attack is not addressed
properly and there are no solid protocols to stop such attacks basically
because such attacks target the physical layer like interfering with the
frequency band.
Summary
In this chapter, we considered attacks and mitigation techniques assuming a switched
Ethernet network running IP. If your network does not use Ethernet as layer 2
protocol, some of these attacks may not be applicable, but chances are such network
is vulnerable to different types of attacks.
Security is only as strong as the weakest link. When it comes to networking, layer 2
can be a very weak link. Layer 2 security measures mentioned in this chapter go a
long way towards protecting a network from many types of attacks.
Network Security – Access Control
Network access control is a method of enhancing the security of a private
organizational network by restricting the availability of network resources to endpoint
devices that comply with the organization’s security policy. A typical network access
control scheme comprises of two major components such as Restricted Access and
Network Boundary Protection.
Restricted Access to the network devices is achieved through user authentication and
authorization control which is responsible for identifying and authenticating different
users to the network system. Authorization is the process of granting or denying
specific access permissions to a protected resource.
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