three-headed dog guards your network so passwords never have to travel twice.
means a network authentication protocol that lets two computers prove their identities to each other using encrypted tickets instead of passwords sent over the wire.
from built at MIT in the 1980s under project athena, named after the multi-headed hound that guards the underworld in greek myth, because it guards the gates between untrusted networks and trusted services.
active directory — microsoft made it the backbone of windows domain logins since 2000
mit project athena — born in 1988 to secure shared campus workstations
apple open directory — macos uses kerberos for network account authentication
hadoop clusters — big data systems use it to authenticate nodes at scale