TACACS+ (Terminal Access Controller Access-Control System Plus) is a network security protocol that provides centralized authentication for users who are attempting to gain access to the network. It is designed to protect against sniffing attacks by encrypting the entire packet, which includes both the authentication credentials and the subsequent communication after the credentials have been accepted. This encryption ensures that sensitive information such as user passwords is not transmitted in plain text where it could be intercepted by unauthorized individuals. Unlike RADIUS, which only encrypts the password, TACACS+ encrypts the entire authentication process, providing a higher level of security.