D-Link DGS-3200-10 Product Manual - Page 166

xStack® DGS-3200 Series Layer 2 Gigabit Ethernet Managed Switch Access Authentication Control The TACACS / XTACACS / TACACS+ / RADI US commands allow users to secure access to the Switch using the TACAC S / XTACACS / TACACS+ / RADIUS protocols. When a user logs in to the Switch or tries to access the administrator level privilege, he or she is prompted for a password. If TACACS / XTACACS / TACACS+ / RADIUS authentication is enabled on the Switch, it will contact a TACACS / XTACACS / TACACS+ / RADIUS server to verify the user. If the user is verified, he or she is granted access to the Switch. There are curren tly three versions of the TACACS security protocol, each a separate entity. The Switch's software supports the following versions of TACACS:  TACACS (Terminal A ccess Controller A ccess Con trol System) - Provides p assword ch ecking an d au thentication, and notification of u ser action s fo r secu rity pu rposes u tilizing via o ne or m ore cen tralized TACACS serv ers, u tilizing the UDP protocol for packet transmission.  Extended TA CACS ( XTACACS) - An ex tension of the TACACS protocol with the ability to p rovide more typ es o f authentication requests and more typ es of resp onse codes than T ACACS. This protocol al so us es U DP t o t ransmit packets.  TACACS+ (Terminal Ac cess Controll er A ccess Contr ol System plus ) - Provides detailed access c ontrol for authentication for n etwork d evices. TAC ACS+ is facilitate d th rough Au thentication co mmands via one or mo re centralized servers. The T ACACS+ protocol encrypts all traffic betwee n the Switch and the TACACS+ daemon, using the TCP protocol to ensure reliable delivery In order for the TACACS / XTACACS / TACACS+ / RADIUS security function to work properly, a TACACS / XTACACS / TACACS+ / RADIUS server must be co nfigured on a device other than the Switch, called an Authentication Server Host and it must i nclude usernames and pass words f or aut hentication. When t he user i s p rompted by t he S witch t o e nter usernames and passwords for authentication, th e Switch con tacts th e TACACS / XTACA CS / TA CACS+ / RADIU S server to ver ify, and the server will respond with one of three messages: The server verifies the username and password, and the user is granted normal user privileges on the Switch. The server will not accept the username and password and the user is denied access to the Switch. The server doesn't respond to the verification query. At this point, the Switch receives the timeout from the server and then moves to the next method of verification configured in the method list. The Switch has four built-in Authentication Server Groups, one for each of t he TACACS, XTACACS, TACACS+ and RADIUS protocols. These built-in Authentication Server Groups a re used to aut henticate users trying to access the Switch. The users will set Authentication Server Hosts in a preferable order in the built-in Authentication Server Groups and wh en a user tries to gain access to the Switch, the Switch will ask the first Authentication Server Hosts for authentication. If no authentication is made, the second server host in the list will b e queried, and so on. The built-in Authentication Server Groups can only have hosts that are running the specified protocol. For example, the TACACS Authentication Server Groups can only have TACACS Authentication Server Hosts. The ad ministrator fo r the Switch m ay set up six different au thentication tech niques per user-defined m ethod list (TAC ACS / XTACACS / TACACS+ / R ADIUS / lo cal / n one) for authentication. These techniques will b e listed in an order preferable, and defined by the user for normal user authentication on the Switch, and may contain up to eight authentication techniques. When a user attempts to access the Switch, t he Switch will select the first tec hnique listed for authentication. If t he first technique goes through its Auth entication Server Hosts and no au thentication is returned, the Switch will then go to th e next technique listed in the server group for authentication, until the authentication has been verified or denied, or the list is exhausted. Please note that users granted access to t he Switch will be grante d normal user pri vileges on the Switch. To gai n access to administrator level privileges, the user must access the Enable Admin window and then enter a password, which was previously configured by the administrator of the Switch. NOTE: TACACS, XTACACS and TACACS+ are separate entities and are not compatible. The Switch and the server must be configured exactly the same, using the same protocol. (For example, if the Switch is set up for TACACS authentication, so must be the host server.) 153