1.2.5 Set 'access-class' for 'line vty' (2024)

FAQs

How to apply ACL on line Vty? ›

To configure standard or extended ACL on a vty line, we use the 'access-class {access-list-number|access-list-name} {in|out}' configuration commands. We enter the command under the vty line configuration mode. For our example, we have routers R1, R2, and R3 here. We want R1 to allow connections with R2 but not with R3.

Virtual teletype (VTY) is a command line interface that gives users access to a device's control plane, most often in network devices like routers and switches. By using it, administrators can configure, manage, and monitor the device remotely. VTY lines are logical interfaces of a device.

It defines how many VTY's that are active on the device and essentially how many simultaneous remote connections you want to allow/support. In case of "line vty 0 4", you can have five simultaneous connections.

Configure the access-list on the vty lines using the access-class command. Verify your configuration and connectivity using R2 and R3.

To use Set-Acl , use the Path or InputObject parameter to identify the item whose security descriptor you want to change. Then, use the AclObject or SecurityDescriptor parameters to supply a security descriptor that has the values you want to apply. Set-Acl applies the security descriptor that is supplied.

What is considered a best practice when configuring ACLs on vty lines? Place identical restrictions on all vty lines. Remove the vty password since the ACL restricts access to trusted users. Apply the ip access-group command inbound.

The virtual terminal or “VTY” lines are virtual lines that allow connecting to the device using telnet or Secure Shell (SSH). Cisco devices can have up to 16 VTY lines. You can determine how many VTY lines you have by issuing “line vty 0 ?” from global configuration mode.

Configure the virtual terminal (vty) lines for the switch to allow Telnet access. If you do not configure a vty password, you will not be able to Telnet to the switch.

Passwords on VTY lines are used to control access to the router itself. By default, it only provides non-privileged access, so you can't change any configuration.

line vty 0 15

This command configures the first sixteen virtual terminal lines, numbered from 0 to 15. This means the device can support up to 16 simultaneous remote connections.

How to configure line Vty and use telnet? ›

The “line vty” command enable the telnet and the “0″ is just let a single line or session to the router. If you need more session simultaneously, you must type “line vty 0 10“. The “password” command set the “Pass123” as password for telnet. You can set your own password.

The number of VTY lines is really the maximum number of possible connections. So, 0 to 15 allows up to sixteen simulataneous telnet or ssh sessions into the router; sixteen people could log in all at once. Older equipment was limited to only five simulatanous lines (hence 0 to 4).

Access lists control the transmission of packets on an interface, control Virtual Terminal Line (VTY) access, and restrict the contents of routing updates. The Cisco IOS software stops checking the extended access list after a match occurs. VTY ACLs control what addresses may attempt to log in to the router.

vty stands for Virtual Teletype and is used to configure a virtual port to get the telnet or ssh access of the Cisco Router/Switch. Cisco hardware support up to 16 virtual port, i.e. (0,1,2,…. 15), on which administrators can telnet/ssh to gain remote access simultaneously.

The 'access-class' setting restricts incoming and outgoing connections between a particular vty (into a Cisco device) and the networking devices associated with addresses in an access list.

To apply an IPv6 ACL to a vty interface, you use the new ipv6 access-class command. The ipv6 traffic-filter command is still used to apply an IPv6 ACL to interfaces.

You can define ACLs on the VLAN interfaces to apply access control to both the ingress and egress routed traffic. You can define a VACL to apply access control to the bridged traffic.

If you use extended ACLs to secure the VTY lines, the router will examine each incoming packet only to determine whether the packet is attempting to reach the VTY lines. Because of the above-listed reasons, administrators usually use standard ACLs to secure VTY lines.