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MAC addresses are uniquely assigned to each card, so using MAC filtering on a network permits and denies network access to specific devices through the use of blacklists and whitelists. While the restriction of network access through the use of lists is straightforward, an individual person is not identified by a MAC address, rather a device only, so an authorized person will need to have a whitelist entry for each device that he or she would use to access the network.
While giving a wireless network some additional protection, MAC filtering can be circumvented by using a packet analyzer to find a valid MAC and then using MAC spoofing to access the network using that address. MAC Address filtering can be considered as Security through obscurity because the effectiveness is based on "the secrecy of the implementation or its components".
MAC filtering is not an effective control in wireless networking as attackers can eavesdrop on wireless transmissions. However MAC filtering is more effective in wired networks, since it is more difficult for attackers to identify authorized MACs.
MAC filtering is also used on enterprise wireless networks with multiple access points to prevent clients from communicating with each other. The access point can be configured to only allows clients to talk to the default gateway, but not other wireless clients. It increases the efficiency of access to network
Many devices that support MAC filtering do so on a device basis. Whitelisted MAC addresses are allowed through any port on the device and blacklisted MAC addresses are blocked on all ports. Other devices, such as Cisco Catalyst switches, support MAC filtering on a port-by-port basis. This is referred to as port security. Port security may be configured statically with a list, dynamically based on the first given number of addresses detected, or a combination of these two methods. When port security is configured, the default settings are to allow only one MAC address per port, and to shut down the port if the allowed number of addresses is exceeded.
- "Configuring Port Security". Cisco. Retrieved 14 November 2015.
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