nis_intro(7)						 Miscellaneous Information Manual					      nis_intro(7)

NAME

       nis_intro - Network Information Service (NIS) introductory information

DESCRIPTION

       The Network Information Service (NIS) is a distributed name service that allows participating hosts to share access to a common set of sys-
       tem and network files.  NIS allows the system administrator to manage these shared files on a single system.

       NIS is intended for use in a secure environment only, where gateways do not allow outside Internet access to the NIS protocol.

   NIS Maps
       Information distributed by NIS is stored in database files called maps.	Most of the NIS  maps  represent  files  that  were  traditionally
       stored in the /etc directory.  These files include the following: aliases group hosts netgroups networks passwd protocols rpc services

       In  a  secure environment, you can run NIS in a secure mode, thereby creating secure and nonsecure versions of the NIS maps.  See the Secu-
       rity guide for more information.

       You can also use NIS to distribute files used by Automount or AutoFS, or to distribute other user-defined files.

       Each NIS map contains a set of keys and associated values.  For example, as keys, the hosts map contains all host names on a  network,  and
       as values, the corresponding Internet addresses.  Each NIS map has a map name, used by programs to access data in the map.

   NIS Domains
       A  named  set  of NIS maps is called a domain.  A system's "domain name" or "NIS domain" corresponds to the set of NIS maps that the system
       can access.  You can think of an NIS domain as a set of systems that share the same set of NIS maps.

       A system's domain name is set at the time the system is booted by the /sbin/init.d/nis script using an entry in	the  /etc/rc.config.common
       file.   System  administrators  can use the nissetup script to place entries in this file.  The nissetup script is described in the Network
       Administration manual.

       You can determine your system's NIS domain using the domainname command.  Refer to domainname(1).  A domain name is required for retrieving
       data from an NIS database.

   NIS Client-Server Model
       NIS  follows  the  client-server  model of distributed services.  There are two types of NIS servers - master and slave.  The master server
       stores the master copy of the NIS maps for its domain; these are the only NIS maps that can be modified.  Each domain has only  one  master
       server.

       Slave  servers store copies of the master server's NIS maps.  NIS slave servers can be spread throughout a network.  Whenever an NIS map is
       updated on the master server, the master propagates the changes to each slave server in its domain.  If the master is unavailable  for  any
       reason, the slave servers continue to make the NIS maps available to the NIS clients.

       Clients are all of the systems that can access NIS maps.  When a client requires NIS information, it makes a remote procedure call (RPC) to
       one of the NIS servers to obtain the information.

   NIS Data Storage
       The data in NIS maps is stored as databases in dbm/ndbm, btree, or hash format.

       For example, the NIS map  for  the  /etc/hosts  file  in  the  domain  market  might  be  stored  in  these  dbm/ndbm  files:  /var/yp/mar-
       ket/hosts.byaddr.dir
       /var/yp/market/hosts.byaddr.pag
       /var/yp/market/hosts.byname.dir
       /var/yp/market/hosts.byname.pag

       The  makedbm  command  takes an ASCII file such as /etc/hosts and converts it into dbm/ndbm files suitable for use by NIS.  However, system
       administrators use the Makefile script in the /var/yp directory to create NIS map files and specify file format.  The Makefile script  then
       calls makedbm.

       Refer  to  the  Network	Administration	manual	for details on the Makefile script, specifying different formats, and other NIS management
       information.

RELATED INFORMATION

       Commands: domainname(1), svcsetup(8), ypbind(8), yppasswdd(8), ypserv(8), ypxfr(8)

       Files: svc.conf(4)

       Network Administration delim off

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