To access a Cisco device using telnet, you first need to enable remote login. Cisco devices usually supports 16 concurrent virtual terminal sessions, so the first command usually looks like this:
HOSTNAME(config)line vty 0 15
To enable remote login, the login command is used from the virtual terminal session mode:
HOSTNAME(config-vty)login
Next, you need to define a password. This is done using the password command from the virtual terminal session mode:
HOSTNAME(config-vty)password PASSWORD
Let’s try this on a real router. First, we will try to access the router without enabling telnet on a device:
As you can see in the picture above, we can not access a Cisco device using telnet before setting up the password. Let’s do that:
Now, let’s try to access our device:
This time, because telnet was configured on the device, we have successfully telnetted to the device.