zephyrd - Zephyr server daemon
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.
communicates with daemons running on other Zephyr server hosts,
to provide a reliable service.
While running, any unusual conditions are recorded via syslog(3)
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 zephyrd
s executing on the
other known servers. This initialization is only performed after the
s have authenticated themselves to each other via Kerberos. The
server then enters a dispatch loop, servicing requests from clients and other
enables logging of additional debugging information.
disables the logging of additional debugging information.
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
to dump the location and subscription
databases to /var/tmp/zephyr.db
in an ASCII format.
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 registry lists all classes which are restricted.
- List of classes which are restricted
- Access Control Lists for instance-wildcard restrictions
- Access Control Lists for instance-identity restrictions
- Access Control Lists for subscribing
- Access Control Lists for transmitting
- Kerberos 4 Service keys
- Kerberos V Service keys
- Current Kerberos tickets for exchange with other servers
- File containing an ASCII dump of the database.
The current implementation of the Zephyr server ( zephyrd(8)
) makes no
distinction between realm-announced, net-visible and net-announced exposure
zephyr(1), zhm(8), kerberosintro(1), hesiod(3), access_control_lists(?),
Athena Technical Plan, Sections E.4.1 (Zephyr Notification Service) and E.2.1
(Kerberos Authentication and Authorization System)
John T. Kohl, MIT Project Athena and Digital Equipment Corporation
Copyright (c) 1987,1988 by the Massachusetts Institute of Technology. All Rights
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