Why do we need no firewall, VPN, username and password on dfinity?

The document wrote “You won’t need a firewall, a VPN, usernames and passwords”. I know that usernames and passwords can be replaced by the Asymmetric key,but I am not very clear about the mechanism of access control on dfinity?

Hello @tingfei

You can add access control based on authenticating the msg.caller of the update calls.

See Add access control with identities :: Internet Computer