RADIUS, Diameter, and TACACS RADIUS and TACACS are systems that authenticatethe credentials of users who are trying to access an organizations network via a dial-upconnection. Typical dial-up systems place the responsibility for user authentication on the systemdirectly connected to the modems. If there are multiple points of entry into the dial-upsystem, this authentication system can become difficult to manage. The Remote AuthenticationDial-In User Service (RADIUS) system centralizes the responsibility for authenticating eachuser on the RADIUS server. RADIUS was initially described in RFCs 2058 and 2059, and iscurrently described in RFCs 2865 and 2866, among others.

The Terminal Access Controller Access Control System (TACACS), defined in RFC 1492, isanother remote access authorization system that is based on a client/server configuration.Like RADIUS, it contains a centralized database, and it validates the users credentials atthis TACACS server. The three versions of TACACS are the original version, ExtendedTACACS, and TACACS. Of these, only TACACS is still in use. The original versioncombines authentication and authorization services. The extended version separates thesteps needed to authenticate individual user or system access attempts from the steps neededto verify that the authenticated individual or system is allowed to make a given type of connection.The extended version keeps records for accountability and to ensure that the accessattempt is linked to a specific individual or system. The TACACS version uses dynamicpasswords and incorporates two-factor authentication.

What is LDAP? What is a content filter? What is a bastion host? What is Kerberos? look at the MIT website. What if Kerberos is hacked?

What is VPN? What if you neighbor hacks into your VPN?