Telnet is a command-line client and protocol for remotely connecting to the CLI of routers and switches. It uses a client-server model: the user’s computer is the client, and the network device is the server. Telnet sends usernames, passwords, and other data in cleartext, so SSH has largely replaced it for secure management. section 5.2.2 section 5.4
A Cisco IOS Telnet deployment typically requires:
- An enable secret or enable password, so the enable command works during a remote session. section 5.2.2
- A local user account, such as username jeremy secret ccna, with login local configured on the VTY lines. section 5.2.2
- VTY-line settings such as access-class 1 in, exec-timeout 20 0, login local, and transport input telnet. section 5.2.2
- An IP address on the device; a Layer 2 switch additionally needs a management SVI and default gateway. section 5.4
Connecting from a host
Running telnet 10.0.0.2 from PC2 prompts for the configured username and password, then places the user at the SW1> CLI prompt. An access list can restrict VTY access to 192.168.1.0/24. section 5.2.2
