Aamir Lakhani wrote a fantastic post on 802.1x for DOD. You can find the original posting at www.cloudcentrics.com
The Department of Defense added a requirement that all network ports, or on-ramps need to be protected. Applications, server, and data are normally protected; however, most network ports are left open. You get on to a network by plugging into a port and a network address is allocated for the connection. Computers without proper are free to launch attacks from the network. Network port protection lock down restricts anonymous access and prevents these “attacks”.
When network protection is turned on, a machine plugs into the network; no network access is given until the machine is authenticated to the network.
A few years ago, NAC solutions tried to accomplish goals for locking down networks. Most of my customers hated NAC. It added a layer of complexity that made the network behave unnatural and harder to support. It used a variety of ports, protocols, and physical boxes to implement. In short, it was complicated. NAC supported networks broke down often, causing nightmares for those legitimate users trying to get access and the people supporting those networks.
What are people doing to support port lockdown today at the Department of Defense and other large enterprise organizations? Surprisingly, the solution has been around for a long time to help secure wireless networks. It is called 802.1x. Historically, 802.1x has worked great on wireless networks and has always been a little troublesome on the wired ports. But things have changed with enterprise policy servers (Cisco Identity Services) that make the connection more easily configurable on modern day operating systems such as Mac OS X Mountain Lion and Windows 8.
How does 802.1x work? According to Wikipedia, IEEE 802.1X is an IEEE Standard for port-based Network Access Control (PNAC) that provides an authentication mechanism to devices wishing to attach to a LAN or WLAN. It is part of the IEEE 802.1 group of networking protocols.
802.1X authentication involves three parties: a supplicant, an authenticator, and an authentication server. The supplicant is a client device (such as a laptop) that wishes to attach to the LAN/WLAN. The term ‘supplicant’ is also used interchangeably to refer to the software running on the clients’ device that provides credentials to the authenticator. The authenticator is a network device, such as an Ethernet switch or wireless access point. And the authentication server is typically a host running software supporting the RADIUS and EAP protocols.
The authenticator acts like a security guard to a protected network. The supplicant (i.e., client device) is not allowed access through the authenticator to the protected side of the network until the supplicant’s identity has been validated and authorized. A similar comparison to this would be providing a valid visa at the airport’s arrival immigration booth before being allowed to enter the country. With 802.1X port-based authentication, the supplicant provides credentials, such as user name / password or digital certificate, to the authenticator and the authenticator forwards the credentials to the authentication server for verification. If the authentication server determines that the credentials are valid, the supplicant (client device) is allowed to access resources located on the protected side of the network. Continue reading
