Summary

This chapter is the introduction and foundation on which we will build that. As a rehash on important points discussed, be sure to know the following facts:

Name	Stands for	Short description
AAA	Authentication, Authorization, and Accounting	The three components required for proper control of access and usage.
NAS	Network Access Server	A device controlling access to the network for example, a VPN server. Acts as the RADIUS client.
AVP	Attribute Value Pair	A three-field component inside a RADIUS packet used to contain a specified field and its data.
VSA	Vendor-Specific Attributes	An extension of the AVP managed by a specific vendor.

• AAA is a security architecture model.
• RADIUS is a specific implementation of AAA.
• FreeRADIUS is a practical application of RADIUS.
• Thus we have AAA → RADIUS → FreeRADIUS.
• RADIUS is all about central control and is the de facto standard supported by NAS vendors.
• RADIUS is a client/server protocol. It uses UDP and listens on port 1812 for authentication and port 1813 for accounting requests.
• RADIUS data packets have a code field, which specifies the type of RADIUS packet.
• RADIUS data packets have zero or more AVPs, which contain the data used in RADIUS.
• FreeRADIUS implements the RADIUS protocol along with its various extensions as specified in RFCs.
• FreeRADIUS is a very popular, widely used, and very flexible RADIUS server.

This chapter was a FreeRADIUS starter. The main course begins with the next chapter where we'll be installing FreeRADIUS and starting to use it.

Pop quiz – RADIUS knowledge

1. Explain the term NAS device.
2. What are the start and end points of a session?
3. Which protocol and ports does RADIUS use?
4. What do the RADIUS client and server require for successful communication?
5. What packet does the RADIUS client send when authenticating a user?
6. Who initiates a Disconnect Request packet and who receives it?
7. Name three components of an Attribute Value Pair (AVP).
8. Alice connects with username [e-mail] to a network. What is the name of the realm to which Alice belongs?