zephyr-server-krb5 binary package in Ubuntu Trusty arm64

 You probably only need one server for a group of clients.
 This can be a memory-intensive server, especially for very large sites.
 .
 The server maintains a location and subscription database for all the
 receiving clients. All zephyrgrams are sent to the server to be routed
 to the intended recipient.
 .
 This version of the server uses Kerberos V for message authentication.
 .
 This is the Project Athena Zephyr notification system.
 Zephyr allows users to send messages to other users or to groups of
 users. Users can view incoming Zephyr messages as windowgrams
 (transient X windows) or as text on a terminal.

Source package