nis_intro(7)nis_intro(7)NAMEnis_intro - Network Information Service (NIS) introductory information
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.
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 cre‐
ating secure and nonsecure versions of the NIS maps. See Security
Administration 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 exam‐
ple, 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.
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: Services manual.
You can determine your system's NIS domain using the domainname com‐
mand. 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 rea‐
son, the slave servers continue to make the NIS maps available to the
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
For example, the NIS map for the /etc/hosts file in the domain market
might be stored in these dbm/ndbm files:
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 admin‐
istrators use the Makefile script in the /var/yp directory to create
NIS map files and specify file format. The Makefile script then calls
Refer to the Network Administration: Services manual for details on the
Makefile script, specifying different formats, and other NIS management
Commands: domainname(1), svcsetup(8), ypbind(8), yppasswdd(8),
Network Administration: Services