Cisco Systems CCNA 2 Guia do Utilizador descarregar pdf (Página 129)

11.2.6 Restricting virtual terminal access

Standard and extended access lists apply to packets that travel through a router. They are not

designed to block packets that originate within the router. By default, an outbound Telnet

extended access list does not prevent router initiated Telnet sessions. This type of ACL

controls which users can telnet into a remote router. To test this in the labs, have students

configure routers and telnet into a remote router to test connectivity. Configure and apply the

ACL to the vty lines to deny access. Then test the Telnet again. Here are the commands to

configure virtual terminal access:

Rt1(config)#access-list 2 permit 172.16.1.0 0.0.0.255

Rt1(config)#access-list 2 permit 172.16.2.0 0.0.0.255

Rt1(config)#access-list 2 deny any

Here are the commands to apply the access list:

Rt1(config)#line vty 0 4

Rt1(config-line)#login

Rt1(config-line)#password secret

Rt1(config-line)#access-class 2 in

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Cisco Systems CCNA 2 Guia do Utilizador Página 129