Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 73

Terminal Lines You can access the system remotely and restrict access to the system by creating user profiles. Terminal lines on the system provide different means of accessing the system. The console line (console) connects you through the console port in the route processor modules (RPMs). The virtual terminal lines (VTYs) connect you through Telnet to the system. The auxiliary line (aux) connects secondary devices such as modems. Denying and Permitting Access to a Terminal Line Dell Networking recommends applying only standard access control lists (ACLs) to deny and permit access to VTY lines. • Layer 3 ACLs deny all traffic that is not explicitly permitted, but in the case of VTY lines, an ACL with no rules does not deny traffic. • You cannot use the show ip accounting access-list command to display the contents of an ACL that is applied only to a VTY line. • When you use the access-class access-list-name command without specifying the ipv4 or ipv6 attribute, both IPv4 as well as IPv6 rules that are defined in that ACL are applied to the terminal. This method is a generic way of configuring access restrictions. • To be able to filter access exclusively using either IPv4 or IPv6 rules, use either the ipv4 or ipv6 attribute along with the accessclass access-list-name command. Depending on the attribute that you specify (ipv4 or ipv6), the ACL processes either IPv4 or IPv6 rules, but not both. Using this configuration, you can set up two different types of access classes with each class processing either IPv4 or IPv6 rules separately. To apply an IP ACL to a line, Use the following command. • Apply an ACL to a VTY line. LINE mode access-class access-list-name [ipv4 | ipv6] NOTE: If you already have configured generic IP ACL on a terminal line, then you cannot further apply IPv4 or IPv6 specific filtering on top of this configuration. Similarly, if you have configured either IPv4 or IPv6 specific filtering on a terminal line, you cannot apply generic IP ACL on top of this configuration. Before applying any of these configurations, you must first undo the existing configuration using the no access-class access-list-name [ipv4 | ipv6] command. Example of an ACL that Permits Terminal Access Example Configuration To view the configuration, use the show config command in LINE mode. Dell(config-std-nacl)#show config ! ip access-list standard myvtyacl seq 5 permit host 10.11.0.1 Dell(config-std-nacl)#line vty 0 Dell(config-line-vty)#show config line vty 0 access-class myvtyacl Dell(conf-ipv6-acl)#do show run acl ! ip access-list extended testdeny seq 10 deny ip 30.1.1.0/24 any seq 15 permit ip any any ! ip access-list extended testpermit seq 15 permit ip any any ! ipv6 access-list testv6deny seq 10 deny ipv6 3001::/64 any seq 15 permit ipv6 any any Management 73