foreverlearning said: What happens if I do this?username admin password cisco!line vty 0 4login transport input telnetI specify username and password but telnet only requires password.
foreverlearning said: What happens if I do this?line vty 0 4logintransport input sshThere is no password but ssh is allowed. I believe that ssh requires both username and password. Am I right to say this?
JDMurray said: foreverlearning said: What happens if I do this?username admin password cisco!line vty 0 4login transport input telnetI specify username and password but telnet only requires password. GPT-4 sez: In your configuration, you've set up a local username and password (`username admin password cisco`), but in your VTY lines configuration, you've only specified `login` and not `login local`. The `login` command without `local` only requires a line password for access and doesn't reference the local username database. Since you've not set a password for the VTY lines (using the `password <password>` command), users won't be able to access the device via Telnet, as it will ask for a password that is not set.The `login local` command, on the other hand, would require a valid username/password pair from the local username database.If you want to use the local username and password, you would need to use `login local`. If you want to use Telnet with just a password and not a username, you can set a password on the VTY lines like so:line vty 0 4password ciscologin transport input telnetBut please remember, Telnet is not secure as it sends all data, including passwords, in clear text. It's recommended to use SSH instead. foreverlearning said: What happens if I do this?line vty 0 4logintransport input sshThere is no password but ssh is allowed. I believe that ssh requires both username and password. Am I right to say this? GPT-4 sez: Yes, you're correct. SSH does indeed require a username and password. However, in your configuration, you've enabled SSH but have not provided a password for the VTY lines, nor have you provided a local user database using the `username <username> password <password>` command.The `login` command on its own will attempt to use line passwords, but since you didn't specify a password with the `password` command under `line vty 0 4`, SSH connections will fail because there's no password set.If you want to use SSH, you should create a local user database and specify `login local` under the VTY lines. You should also create a domain name and generate cryptographic keys, which are required for SSH. Here's an example:ip domain-name yourdomain.comcrypto key generate rsa!username admin password cisco!line vty 0 4login localtransport input sshIn this example, replace `yourdomain.com` with your domain name, `admin` with your desired username, and `cisco` with your desired password. Note that it's important to choose a strong, unique password.When you generate RSA keys with `crypto key generate rsa`, you'll be prompted to enter a modulus length. A longer length is more secure, but it requires more processing power. A common choice is 2048 bits.With this configuration, users will be able to SSH into the device using the username "admin" and the password "cisco".
