How to Setup and Configure NIS/YP Services

Brief overiew

NIS (Network Information Service) also known as Yellow-Pagers or YP is a lookup service that allows distribution of administrative databases (maps) across a series of servers (master, slaves and clients).

NIS maps are associated with the passwd file, groups file, hosts file, and a few others. Essentially, NIS is the primary source of a central repository.

NIS Elements

Planning your NIS domain

Before you configure any systems as NIS servers or clients, you must plan the NIS domain.

• Decide which systems will be in your NIS domain. An NIS domain does not have to be congruent with your network. A network can have more than one NIS domain, and there can be machines on your network that are outside of your NIS domain.
• Choose a NIS domainname, which can be 256 characters long. A good practice is to limit domainnames to no more than 32 characters. Domain names are case-sensitive.
• Before a machine can use NIS services, the correct NIS domainname and machine name must be set. A machine's name is set by the machine's /etc/nodename file and the machine's domainname is set by the machine's /etc/defaultdomain file. These files are read at boot time and the contents are used by the uname -S and domainname commands, respectively.
• Select one system to be the master server. Decide which system, if any, will be slave servers.
• Decide which system will be NIS clients. Typically all system in your domain are set to be NIS clients, although this is not necessary.

Configuring NIS Master Server

NOTE:
• You can only have one master server, but multiple slave servers.
• Limit your NIS domainname to a maximum of 32 characters.

If your NIS Master server is already configured, and you just want to connect a server to an existing NIS domain, skip to the Configure NIS Client section below.

If you do not wish to use the default NIS location (/var/yp/etc) for your NIS maps, then edit /var/yp/Makefile, changing the lines DIR= and PWDIR= to match your new location.

CAUTION: Do not use /etc as your source directory, since this is for local files on the master server.

1. Copy the following source files into your NIS directory:

   auto.home auto.master bootparams ethers group hosts ipnodes netgroup netmasks networks passwd protocol rpc service shadow user_attr

   For example:

   root@nismaster# cd /etc
   root@nismaster# cp auto.home auto.master bootparams ethers group hosts ipnodes netgroup netmasks networks passwd protocol rpc service shadow user_attr /data/nis-maps

2. Run ypinit -m to convert these source files into ndbm formatted NIS maps.
3. Confirm that /etc/nsswitch.conf file looks how you want to look. A quick method is to copy /etc/nsswitch.nis to /etc/nsswitch.conf (if this works for your setup).
4. Add the <ip address> and <hostname> of all your NIS servers to /etc/hosts.
5. Build the new maps on the master NIS server:

   root@nismaster# /usr/sbin/ypinit -m

   If some of the NIS map files are not present you may get a nonfatal error. Review and correct these errors, and rerun the ypinit again.
6. Start NIS services on your master server, using one of the following methods:
   • Using /usr/lib/netsvc/yp/ypstart during boot process (simply reboot your server)
   • Use svcadm to enable/disable the NIS services
   • Run ypstart, ypstop from command-line.

Configuring NIS Slave Server

1. Add all other NIS servers to /etc/hosts file on your NIS slave server.
2. Firstly, initialise the server as a NIS client in order to get NIS maps from the NIS master for the first time before promoting the server to a NIS slave. For example:

   root@nisslave# /usr/sbin/ypinit -c

   You'll be prompted for list of NIS servers, enter name of local slave you are working on, then master, followed by other slaves.
3. Start the NIS client service, using:

   root@nisslave# svcadm enable -r svc:/network/nis/client

   Make sure NIS is running, just restart with: ypstop / ypstart.
4. Initialize this server as a NIS slave server:

   root@nisslave# ypinit -s nis_master_server

Configure NIS Client

1. Add your NIS servers to /etc/hosts file on the client machine.
2. Confirm /etc/nsswitch.conf file looks how you want to look. A quick method is to copy /etc/nsswitch.nis to /etc/nsswitch.conf (if this works for your setup).
3. Inialise server as a NIS client, running:

   root@nisclient# /usr/sbin/ypinit -c

4. Start NIS client services:

   root@nisclient# svcadm enable -r svc:/network/nis/client

5. Reboot your NIS client.

Basic NIS Administration

• ypwhich — Returns the name of the NIS server used, or the master server for a given database
• Check ypserv daemon is running only on the NIS server (this handles requests from clients and send info to them)
• Check ypbind daemon is running on all servers and clients (check ypservers file and initiate binding to fist server, or any other available)
• ypinit — creates maps from input files
• ypxfr — pulls maps from remote server to local /var/yp/domain dir - you can run from crontab file
• ypxfrd daemon runs only on master server and provides services for ypxfr
• yppush — Copies new maps from master to slaves, run it on master
• yppoll — Returns the server name and NIS version for a given database

Examples

ypcat

The ypcat command prints out the NIS map you specify. You can specify either a map name or a map nickname. Because the ypcat command uses the NIS service, you do not need to specify a server.

Synopsis

ypcat [ -d <domainname> ]  <map>

Examples

• Look at the networkwide password map (passwd.byname):

  # ypcat passwd

• Display a map in another NIS domain:

  # ypcat -d altdomain passwd

• Find a specific entry (myusername) in the NIS passwd map:

  # ypcat passwd | grep myusername

ypmatch

The ypmatch command displays the values associated with one or more keys within a NIS map.

Synopsis

ypmatch [ -d <domainname> ]  <key>  <map>

Examples

• Display the value associated with the myusername key in the passwd map:

  # ypmatch myusername passwd

• Display the value associated with the myusername key in the passwd map in a specific domain:

  # ypmatch -d altdomain myusername passwd