Solaris Naming Administration Guide

NIS Elements

The NIS service is composed of the following elements:

Domains (see "The NIS Domain")
Maps (see "NIS Maps")
Daemons (see "NIS Daemons")
Utilities (see "NIS Utilities")
NIS Command Set (see "Summary of NIS-Related Commands")

The NIS Domain

An NIS domain is a collection of machines that share a common set of NIS maps. Each domain has a domain name and each machine sharing the common set of maps belongs to that domain. Domain names are case-sensitive.

Any machine can belong to a given domain, as long as there is a server for that domain's maps in the same network. Solaris Release 2 machines do not require the server to be on the same subnet, but earlier implementations of NIS historically have required that a server exist on every subnet using NIS. A NIS client machine obtains its domain name and binds to a NIS server as part of its boot process.

NIS Daemons

NIS service is provided by five daemons as shown in Table 18-1.

Table 18-1 NIS Daemons


Daemon	Function
`ypserv`	Server process
`ypbind`	Binding process
`ypxfr`	High speed map transfer
`rpc.yppasswdd`	NIS password update daemon
`rpc.ypupdated`	Modifies other maps such as `publickey`

NIS Utilities

NIS service is supported by nine utilities as shown in Table 18-2.

Table 18-2 NIS Utilities


Utility	Function
`makedbm`	Creates `dbm` file for an NIS map
`ypcat`	Lists data in a map
`ypinit`	Builds and installs an NIS database and initializes NIS client's `ypservers` list.
`yppmatch`	Finds a specific entry in a map
`yppoll`	Gets a map order number from a server
`yppush`	Propagates data from NIS master to NIS slave server
`ypset`	Sets binding to a particular server
`ypwhich`	Lists name of the NIS server and nickname translation table
`ypxfr`	Transfers data from master to slave NIS server

NIS Maps

NIS stores information in a set of files called maps.

NIS maps were designed to replace UNIX /etc files, as well as other configuration files, so they store much more than names and addresses. On a network running NIS, the NIS master server for each NIS domain maintains a set of NIS maps for other machines in the domain to query. NIS slave servers also maintain duplicates of the master server's maps. NIS client machines can obtain name space information from either master or slave servers.

NIS maps are one type of implementation of Solaris databases. (Other types, not necessarily overlapping, are the files generally found in the /etc directory, the DNS resource records (RRs), and NIS+ tables.)

NIS Maps Overview

NIS maps are essentially two-column tables. One column is the key and the other column is information value related to the key. NIS finds information for a client by searching through the keys. Some information is stored in several maps because each map uses a different key. For example, the names and addresses of machines are stored in two maps: hosts.byname and hosts.byaddr. When a server has a machine's name and needs to find its address, it looks in the hosts.byname map. When it has the address and needs to find the name, it looks in the hosts.byaddr map.

Maps for a domain are located in each server's /var/yp/domainname directory. For example, the maps that belong to the domain test.com are located in each server's /var/yp/test.com directory.

An NIS Makefile is stored in the /var/yp directory of machines designated as a NIS server at installation time. Running make in that directory causes makedbm to create or modify the default NIS maps from the input files. (See Solaris Naming Setup and Configuration Guide for a description of using this process to initially set up your NIS name space.)

Note -

Never make the maps on a slave server. Always run make on the master server.

The information in NIS maps is stored in ndbm format. The ypfiles and ndbm man pages explain the format of the map file.

Default NIS Maps

A default set of NIS maps are provided for you. You may want to use all these maps or only some of them. NIS can also use whatever maps you create or add when you install other software products.

Table 18-3 describes the default NIS maps, information they contain, and whether the software consults the corresponding administrative files when NIS is running.

Table 18-3 NIS Map Descriptions


Map Name	Corresponding NIS Admin File	Description
`bootparams`	`bootparams`	Contains path names of files clients need during boot: root, swap, possibly others.
`ethers.byaddr`	`ethers`	Contains machine names and Ethernet addresses. The Ethernet address is the key in the map.
`ethers.byname`	`ethers`	Same as `ethers.byaddr`, except the key is machine name instead of the Ethernet address.
`group.bygid`	`group`	Contains group security information with group ID as key.
`group.byname`	`group`	Contains group security information with group name as key.
`hosts.byaddr`	`hosts`	Contains machine name, and IP address, with IP address as key.
`hosts.byname`	`hosts`	Contains machine name and IP address, with machine (host) name as key.
`mail.aliases`	`aliases`	Contains aliases and mail addresses, with aliases as key.
`mail.byaddr`	`aliases`	Contains mail address and alias, with mail address as key.
`netgroup.byhost`	`netgroup`	Contains group name, user name and machine name.
`netgroup.byuser`	`netgroup`	Same as `netgroup.byhost`, except that key is user name.
`netgroup`	`netgroup`	Same as `netgroup.byhost`, except that key is group name.
`netid.byname`	`passwd, hosts` `group`	Used for UNIX-style authentication. Contains machine name and mail address (including domain name). If there is a `netid` file available it is consulted in addition to the data available through the other files.
`netmasks.byaddr`	`netmasks`	Contains network mask to be used with IP submitting, with the address as the key.
`networks.byaddr`	`networks`	Contains names of networks known to your system and their IP addresses, with the address as the key.
`networks.byname`	`networks`	Same as `networks.byaddr`, except key is name of network.
`passwd.adjunct. byname`	`passwd` and `shadow`	Contains auditing information and the hidden password information for C2 clients.
`passwd.byname`	`passwd` and `shadow`	Contains password information with user name as key.
`passwd.byuid`	`passwd` and `shadow`	Same as `passwd.byname`, except that key is user ID.
`protocols.byname`	`protocols`	Contains network protocols known to your network.
`protocols.bynumber`	`protocols`	Same as `protocols.byname`, except that key is protocol number.
`rpc.bynumber`	`rpc`	Contains program number and name of RPCs known to your system. Key is RPC program number.
`services.byname`	`services`	Lists Internet services known to your network. Key is port or protocol.
`services.byservice`	`services`	Lists Internet services known to your network. Key is service name.
`ypservers`	N/A	Lists NIS servers known to your network.

Using NIS Maps

NIS makes updating network databases much simpler than with the /etc files system. You no longer have to change the administrative /etc files on every machine each time you modify the network environment.

For example, when you add a new machine to a network running NIS, you only have to update the input file in the master server and run make. This automatically updates the hosts.byname and hosts.byaddr maps. These maps are then transferred to any slave servers and are made available to all of the domain's client machines and their programs. When a client machine or application requests a machine name or address, the NIS server refers to the hosts.byname or hosts.byaddr map as appropriate and sends the requested information to the client.

You can use the ypcat command to display the values in a map. The ypcat basic format is:

% ypcat mapname

Where mapname is the name of the map you want to examine or its nickname. If a map is composed only of keys, as in the case of ypservers, use ypcat -k; otherwise, ypcat prints blank lines. The ypcat man page describes more options for ypcat.

You can use the ypwhich command to determine which server is the master of a particular map. Type the following:

% ypwhich -m mapname

Where mapname is the name or the nickname of the map whose master you want to find. ypwhich responds by displaying the name of the master server. For complete information, refer to the ypwhich man page.

NIS Map Nicknames

Nicknames are aliases for full map names. To obtain a list of available map nicknames, such as passwd for passwd.byname, type ypcat -x or ypwhich -x.

Nicknames are stored in the /var/yp/nicknames file, which contains a map nickname followed by the fully specified name for the map, separated by a space. This list may be added to or modified. Currently, there is a limit of 500 nicknames.

Summary of NIS-Related Commands

The NIS service includes specialized daemons, system programs, and commands, which are summarized in Table 18-4. Refer to their man pages for details about how to use them.

Table 18-4 NIS Command Summary


Command	Description
`ypserv`	Services NIS clients' requests for information from a NIS map. `ypserv` is a daemon that runs on NIS servers with a complete set of maps. At least one `ypserv` daemon must be present on the network for NIS service to function.
`ypbind`	Provides NIS server binding information to clients. It provides binding by finding a `ypserv` process that serves maps within the domain of the requesting client. `ypbind` must run on all servers and clients.
`ypinit`	Automatically creates maps for an NIS server from the input files. It is also used to construct the initial `/var/yp/binding/domain/ypservers` file on the clients. Use `ypinit` to set up the master NIS server and the slave NIS servers for the first time.
`make`	Updates NIS maps by reading the `Makefile` (when run in the `/var/yp` directory). You can use `make` to update all maps based on the input files or to update individual maps. The ypmake(1M) man page describes the functionality of `make` for NIS.
`makedbm`	`makedbm` takes an input file and converts it into `dbm.dir` and `dbm.pag` files--valid `dbm` files that NIS can use as maps. You can also use `makedbm` `-u` to disassemble a map, so that you can see the key-value pairs that comprise it.
`ypxfr`	Pulls an NIS map from a remote server to the local `/var/yp/domain` directory, using NIS itself as the transport medium. You can run `ypxfr` interactively, or periodically from a `crontab` file. It is also called by `ypserv` to initiate a transfer.
`ypxfrd`	Provides map transfers service for `ypxfr` requests (generally slave servers). It is run only on the master server.
`yppush`	Copies a new version of an NIS map from the NIS master server to its slaves. You run it on the master NIS server.
`ypset`	Tells a `ypbind` process to bind to a named NIS server. This is not for casual use and its use is discouraged because of security implications. See the ypset(1M) and ypbind(1M) man pages for information about the `ypset` and `ypsetme` options to the `ypbind` process.
`yppoll`	Tells which version of an NIS map is running on a server that you specify. It also lists the master server for the map.
`ypcat`	Displays the contents of an NIS map.
`ypmatch`	Prints the value for one or more specified keys in an NIS map. You cannot specify which version of the NIS server map you are seeing.
`ypwhich`	Shows which NIS server a client is using at the moment for NIS services, or, if invoked with the `-m` `mapname` option, which NIS server is master of each of the maps. If only `-m` is used, it displays the names of all the maps available and their respective master servers.