ZEPHYRD(8)      MIT Project Athena (July 1, 1988)      ZEPHYRD(8)

     NAME
          zephyrd - Zephyr server daemon

     SYNOPSIS
          /usr/etc/zephyrd [ -d ]

     DESCRIPTION
          zephyrd is the central server for the Zephyr Notification
          System.  It maintains a location database of all currently
          logged-in users, and a subscription database for each user's
          Zephyr clients.

          zephyrd communicates with daemons running on other Zephyr
          server hosts, to provide a reliable service.

          While running, any unusual conditions are recorded via
          syslog(3) to facility local6 at various levels.  The -d
          option enables logging of additional debugging information.

          When a zephyrd is executed, it requests a list of server
          machines from Hesiod and initializes its state from any
          zephyrds executing on the other known servers.  This
          initialization is only performed after the zephyrds have
          authenticated themselves to each other via Kerberos.  The
          server then enters a dispatch loop, servicing requests from
          clients and other servers.

     SIGNALS
          SIGUSR1 enables logging of additional debugging information.
          SIGUSR2 disables the logging of additional debugging
          information.
          SIGHUP causes zephyrd to re-read the default subscription
          file and to re-query Hesiod about valid peers.  Any peers
          which are not responding and no longer mentioned in Hesiod
          are flushed; any peers not previously named by Hesiod are
          added.
          SIGINT and SIGTERM cause zephyrd to gracefully shut down.
          SIGFPE causes zephyrd to dump the location and subscription
          databases to /usr/tmp/zephyr.db in an ASCII format.

     ACCESS CONTROL
          Certain notice classes are restricted by the Zephyr server.
          Each such class has access control lists enumerating who may
          transmit (xmt-*.acl) or subscribe to that particular class.
          Subscriptions may be restricted either absolutely (sub-*.acl
          files), or by instance restrictions.  iws-*.acl files
          control subscriptions to wildcarded instances.  iui-*.acl
          files control subscriptions to instances which are not the
          Kerberos principal identity of the subscriber.  If an access
          control list of a given type is absent, there is no
          restriction of that type on the class, except that any
          notices of the class must be authenticated.  The class

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     ZEPHYRD(8)      MIT Project Athena (July 1, 1988)      ZEPHYRD(8)

          registry lists all classes which are restricted.

     FILES
          /usr/athena/lib/zephyr/class-registry.acl:
                    List of classes which are restricted

          /usr/athena/lib/zephyr/iws-*.acl:
                    Access Control Lists for instance-wildcard
                    restrictions

          /usr/athena/lib/zephyr/iui-*.acl:
                    Access Control Lists for instance-identity
                    restrictions

          /usr/athena/lib/zephyr/sub-*.acl:
                    Access Control Lists for subscribing

          /usr/athena/lib/zephyr/xmt-*.acl:
                    Access Control Lists for transmitting

          /usr/athena/lib/zephyr/srvtab:
                    Kerberos Service keys

          /usr/athena/lib/zephyr/ztkts:
                    Current Kerberos tickets for exchange with other
                    servers

          /usr/tmp/zephyr.db:
                    File containing an ASCII dump of the database.

     BUGS
          The current implementation of the Zephyr server (zephyrd(8))
          makes no distinction between realm-announced, net-visible
          and net-announced exposure levels.

     SEE ALSO
          zephyr(1), zhm(8), kerberosintro(1), hesiod(3),
          access_control_lists(?), syslog(3)
          Athena Technical Plan, Sections E.4.1 (Zephyr Notification
          Service) and E.2.1 (Kerberos Authentication and
          Authorization System)

     AUTHOR
          John T. Kohl, MIT Project Athena and Digital Equipment
          Corporation

     RESTRICTIONS
          Copyright (c) 1987,1988 by the Massachusetts Institute of
          Technology.  All Rights Reserved.
          zephyr(1) specifies the terms and conditions for
          redistribution.

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