just like how you use "line console 0" to configure stuff for the console, you use "line vty 0" to configure "virtual terminals" or simply, telnet and ssh connections into your router/switch.
From the CBT Nuggets video, I get the impression that if you configure ,
"line vty 0" - you are just going to allow one connection to telnet/ssh into your switch/router
"line vty 0 1" - 2 concurrent connections
"line vty 0 2" - 3 concurrent connections etc. etc.
Older routers/switches with the old IOS will only allow up to line vty 0 4 (5 concurrent connections) and that 's why most books will tell you to use "line vty 0 4" while newer models/IOS allow for line vty 0 15 (16 concurrent connections)
According to Odom, "transport input all" is default on cisco router/switch which allows all methods of connection including both telnet and ssh but if you use "transport ssh" , you are ONLY allowing SSH connections to be established (with the exception of console access) and similarly if you use "transport telnet", you are effectively ONLY allowing telnet connections (with the exception of console access.
FAQs
The abstract “0 - 4” means that the device can allow 5 simultaneous virtual connections which may be Telnet or SSH. In a way, we may say that 5 (0 – 4) are connection ports to the Router or Switch. In fact, we may have connection ports up to 16 (0 – 15).
How to configure vty lines for ssh cisco? ›
There are four steps required to enable SSH support on a Cisco IOS router:
- Configure the hostname command.
- Configure the DNS domain.
- Generate the SSH key to be used.
- Enable SSH transport support for the virtual type terminal (vtys.
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.
What is Vty line configuration? ›
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.
What is the range of values for Vty lines? ›
The value range is 0 to 7 for AUX lines and 0 to 63 for VTY lines. last-number2: Specifies the relative number of the last user line. The value range is 1 to 7 for AUX lines and 1 to 63 for VTY lines.
Why should you configure the Vty lines for the switch? ›
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.
Which step is needed to configure SSH on a switch? ›
Configuring the switch for SSH operation
- Assign a local login (operator) and enable (manager) password. ...
- Generate the switch public and private key pair. ...
- Provide the switch public key to clients. ...
- Enable SSH on the switch and anticipate SSH client contact behavior.
- Configure the switch for SSH authentication.
The Secure Shell (SSH) Integrated Client feature is an application that runs over the SSH protocol to provide. device authentication and encryption. The SSH client enables a Cisco device to make a secure, encrypted. connection to another Cisco device or to any other device running the SSH server.
What is SSH configuration? ›
The SSH protocol creates a secure connection between two remote machines. An SSH config file helps easily configure the default values for these connections and enables efficient streamlining of SSH connections.
How to check line vty connections? ›
To check our vty connectivity, we can use Telnet or SSH (Secure Shell). In our example, we will use Telnet protocol to verify the vty access to R1 via R2. We set the username as 'study' and configure passwords 'ccnp' and enable password 'cisco' beforehand. You can see that the Telnet connectivity went through.
To enable SSH, enter the following commands:
- console> enable.
- console# config.
- console(config)# crypto key generate rsa.
- console(config)# crypto key generate dsa.
- console(config)# ip ssh server.
console 0 is the physical console port on the switch/router you plug into. line vty is when you remote into the switch/router via telnet or ssh. the config-line is letting you know you are currently in configuration mode for that specific line.
How to find how many VTY lines? ›
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.
Why are there 16 VTY lines? ›
vty is the virtual terminal, or telnet. There are 16 total vty sessions available. The numbers represent each session, so vty 5 15 means you are configuring vty sessions 5 through 15.
How many Vty lines do Cisco switches support concurrently? ›
By default all routers have 5 vty lines (factory defaults).
What is line console 0 and line vty? ›
console 0 is the physical console port on the switch/router you plug into. line vty is when you remote into the switch/router via telnet or ssh. the config-line is letting you know you are currently in configuration mode for that specific line. Some commands are also different in relation to them.
What does line con 0 mean? ›
Line con 0 refers to the console port of the switch (it is usually either an RJ-45 or, on newer devices, a USB port). The console port is used to physically connect (a PC or laptop) to the device.
How many VTY lines are on a router? ›
By default all routers have 5 vty lines (factory defaults). Unless you configure the remaining available lines, there is no need for them to be protected.
What is Vty in telnet? ›
Virtual terminals are logical connections from the network to the router; these are typically telnet or rlogin connections. When a user telnets to a router from the network, as in Figure 4-2, the router starts an EXEC process to handle this connection.
