An 802.1x server is integrated with a database of accounts and it provides port-based authentication by requiring users and devices to authenticate before granting them access to a network. If you’re planning on taking the Security+ exam, you should have a basic understanding of authentication methods to increase the level of security including the method used for 802.1x servers.
For example, can you answer this question?
Q. You are planning a wireless network for a business. A core requirement is to ensure that the solution encrypts user credentials when users enter their usernames and passwords. Which of the following BEST meets this requirement?
A. WPA2-PSK
B. WEP over PEAP
C. WPS with LEAP
D. WPA2 over EAP-TTLS
More, do you know why the correct answer is correct and the incorrect answers are incorrect? The answer and explanation is available at the end of this post.
Extensible Authentication Protocol
The Extensible Authentication Protocol (EAP) is an authentication framework that provides general guidance for authentication methods. 802.1x servers typically use one of these methods to increase the level of security during the authentication process. Some methods are:
- EAP. EAP provides a method for two systems to create a secure encryption key, also known as a Pairwise Master Key (PMK). Systems then use this key to encrypt all data transmitted between the devices. Both TKIP or AES-based CCMP use this key, though CCMP is much more secure.
- Protected EAP (PEAP). PEAP provides an extra layer of protection for EAP. The EAP designers assumed that EAP would be used with adequate physical security to ensure the communication channel was secure. In practice, that wasn’t always the case, but PEAP protects the channel. PEAP encapsulates and encrypts the EAP conversation in a Transport Layer Security (TLS) tunnel. PEAP requires a certificate on the server, but not the clients. A common implementation is with Microsoft Challenge Handshake Authentication Protocol version 2 (MS-CHAPv2).
- EAP-Tunneled TLS (EAP-TTLS). This is an extension of PEAP, allowing systems to use some older authentication methods such as Password Authentication Protocol (PAP) within a TLS tunnel. It requires a certificate on the 802.1x server but not the clients.
- EAP-TLS. This is one of the most secure EAP standards and is widely implemented. The primary difference between PEAP and EAP-TLS is that it requires certificates on the 802.1x server and on each of the wireless clients.
- Lightweight EAP (LEAP). Cisco created LEAP using a modified version of the Challenge Handshake Authentication Protocol (CHAP). LEAP does not require a digital certificate. Most wireless devices support LEAP, but it is susceptible to a known attack. Cisco recommends using stronger protocols, instead of LEAP.
Note that PEAP, EAP-TTLS, and EAP-TLS all use digital certificates. Chapter 10 of the CompTIA Security+: Get Certified Get Ahead: SY0-401 Study Guide digs into certificates much deeper, but as an introduction, certificates help provide strong authentication and encryption services. However, a certificate authority (CA) must issue certificates, so an organization must either purchase certificates from a public CA, or implement a private CA within the network.
Remember this
Enterprise mode requires an 802.1x server. PEAP and EAP-TTLS require a certificate on the 802.1x server. EAP-TLS also uses TLS, but it requires certificates on both the 802.1x server and each of the clients. LEAP is proprietary to Cisco.
Q. You are planning a wireless network for a business. A core requirement is to ensure that the solution encrypts user credentials when users enter their usernames and passwords. Which of the following BEST meets this requirement?
A. WPA2-PSK
B. WEP over PEAP
C. WPS with LEAP
D. WPA2 over EAP-TTLS
Answer is D. Wi-Fi Protected Access II (WPA2) over Extensible Authentication Protocol (EAP)-Tunneled Transport Layer Security (EAP-TTLS) is the best solution from the available answers. Because users must enter their usernames and passwords, an 802.1x solution is required. Using EAP-TTLS with an 802.1x solution ensures the credentials are encrypted.
WPA2-preshared key (PSK) does not authenticate users based on their usernames.
Wired Equivalent Privacy (WEP) is not recommended for use even with Protected EAP (PEAP).
Wi-Fi Protected Setup (WPS) is a standard designed to simplify the setup of a wireless network, but it does not implement usernames, and Cisco recommends using stronger protocols rather than Lightweight EAP (LEAP).
