NIS Domain

Vishal Vyas
Linux Guru


To understand the benefits of NFS, consider an example. A school wants to set up a small computer lab for its students.

  • The main Linux server, bigboy, has a large amount of disk space and will be used as both the NIS server and NFS-based file server for the Linux PCs in the lab.
  • Users logging into the PCs will be assigned home directories on bigboy and not on the PCs themselves.
  • Each user’s home directory will be automatically mounted with each user login on the PCs using NFS.
  • The lab instructor will practice with a Linux PC named smallfry before implementing NIS on all the remaining PCs.
  • The suite of NIS RPMs have been installed on the server and client: ypserve and yp-tools are on the server, and ypbind and yp-tools are on the client.

Downloading and installing RPMs isn’t hard, as discussed in Chapter 6, “Installing Linux Software“. When searching for the RPMs, remember that the filename usually starts with the software package name followed by a version number, as in yp-tools-2.8-3.i386.rpm.

The lab instructor did some research and created an implementation plan:

  1. Configure bigboy as an NFS server to make its /home directory available to the Linux workstations.
  2. Configure smallfry as an NFS client that can access bigboy’s /home directory.
  3. Configure bigboy as an NIS server.
  4. Create a user account (nisuser) on bigboy that doesn’t exist on smallfry. Convert the account to a NIS user account.
  5. Configure smallfry as an NIS client.
  6. Test a remote login from bigboy to smallfry using the username and password of the account nisuser.

You have the scenario and the plan, it’s time to get to work.

Configuring The NFS Server

Here are the steps to configure the NFS server in this scenario:

1. Edit the /etc/exports file to allow NFS mounts of the /home directory with read/write access.

/home                   *(rw,sync)

2. Let NFS read the /etc/exports file for the new entry, and make /home available to the network with the exportfs command.

[root@bigboy tmp]# exportfs -a
[root@bigboy tmp]#

3. Make sure the required nfs, nfslock, and portmap daemons are both running and configured to start after the next reboot.

[root@bigboy tmp]# chkconfig nfslock on
[root@bigboy tmp]# chkconfig nfs on
[root@bigboy tmp]# chkconfig portmap on
[root@bigboy tmp]# service portmap start
Starting portmapper: [  OK  ]
[root@bigboy tmp]# service nfslock start
Starting NFS statd: [  OK  ]
[root@bigboy tmp]# service nfs start
Starting NFS services:  [  OK  ]
Starting NFS quotas: [  OK  ]
Starting NFS daemon: [  OK  ]
Starting NFS mountd: [  OK  ]
[root@bigboy tmp]#

After configuring the NFS server, we have to configure its clients, This will be covered next.

Configuring The NFS Client

You also need to configure the NFS clients to mount their /home directories on the NFS server.

These steps archive the /home directory. In a production environment in which the /home directory would be actively used, you’d have to force the users to log off, backup the data, restore it to the NFS server, and then follow the steps below. As this is a lab environment, these prerequisites aren’t necessary.

1. Make sure the required netfs, nfslock, and portmap daemons are running and configured to start after the next reboot.

[root@smallfry tmp]# chkconfig nfslock on
[root@smallfry tmp]# chkconfig netfs on
[root@smallfry tmp]# chkconfig portmap on
[root@smallfry tmp]# service portmap start
Starting portmapper: [  OK  ]
[root@smallfry tmp]# service netfs start
Mounting other filesystems:  [  OK  ]
[root@smallfry tmp]# service nfslock start
Starting NFS statd: [  OK  ]
[root@smallfry tmp]#

2. Keep a copy of the old /home directory, and create a new directory /home on which you’ll mount the NFS server’s directory.

[root@smallfry tmp]# mv /home /
[root@smallfry tmp]# mkdir /home
[root@smallfry tmp]# ll /
drwxr-xr-x    1 root   root     11 Nov 16 20:22 home
drwxr-xr-x    2 root   root   4096 Jan 24  2003
[root@smallfry tmp]#

3. Make sure you can mount bigboy’s /home directory on the new /home directory you just created. Unmount it once everything looks correct.

[root@smallfry tmp]# mount /home/
[root@smallfry tmp]# ls /home
ftpinstall  nisuser  quotauser  smallfry  www
[root@smallfry tmp]# umount /home
[root@smallfry tmp]#

4. Start configuring autofs automounting. Edit your /etc/auto.master file to refer to file /etc/auto.home for mounting information whenever the /home directory is accessed. After five minutes, autofs unmounts the directory.

/home      /etc/auto.home --timeout 600

5. Edit file /etc/auto.home to do the NFS mount whenever the /home directory is accessed. If the line is too long to view on your screen, you can add a \ character at the end to continue on the next line.

*   -fstype=nfs,soft,intr,rsize=8192,wsize=8192,nosuid,tcp \

6. Start autofs and make sure it starts after the next reboot with the chkconfig command.

[root@smallfry tmp]# chkconfig autofs on
[root@smallfry tmp]# service autofs restart
Stopping automount:[  OK  ]
Starting automount:[  OK  ]
[root@smallfry tmp]#

After doing this, you won’t be able to see the contents of the /home directory on bigboy as user root. This is because by default NFS activates the root squash feature, which disables this user from having privileged access to directories on remote NFS servers. You’ll be able to test this later after NIS is configured.

Note: This automounter feature doesn’t appear to function correctly in my preliminary testing of Fedora Core 3. See Chapter 29, “Remote Disk Access with NFS“, for details.

All newly added Linux users will now be assigned a home directory under the new remote /home directory. This scheme will make the users feel their home directories are local, when in reality they are automatically mounted and accessed over your network.

Configuring The NIS Server

NFS only covers file sharing over the network. You now have to configure NIS login authentication for the lab students before the job is done. The configuration of the NIS server is not difficult, but requires many steps that you may overlook. Don’t worry, we’ll review each one in detail.

Note: In the early days, NIS was called Yellow Pages. The developers had to change the name after a copyright infringement lawsuit, yet many of the key programs associated with NIS have kept their original names beginning with yp.

Install the NIS Server Packages

All the packages required for NIS clients are a standard part of most Fedora installations. The ypserv package for servers is not. Install the package according to the steps outlined in Chapter 6,”Installing Linux Software“.

Edit Your /etc/sysconfig/network File

You need to add the NIS domain you wish to use in the /etc/sysconfig/network file. For the school, call the domain NIS-SCHOOL-NETWORK.


Edit Your /etc/yp.conf File

NIS servers also have to be NIS clients themselves, so you’ll have to edit the NIS client configuration file /etc/yp.conf to list the domain’s NIS server as being the server itself or localhost.

# /etc/yp.conf - ypbind configuration file

Start The Key NIS Server Related Daemons

Start the necessary NIS daemons in the /etc/init.d directory and use the chkconfig command to ensure they start after the next reboot.

[root@bigboy tmp]# service portmap start
Starting portmapper: [  OK  ]
[root@bigboy tmp]# service yppasswdd start
Starting YP passwd service: [  OK  ]
[root@bigboy tmp]# service ypserv start
Setting NIS domain name NIS-SCHOOL-NETWORK:  [  OK  ]
Starting YP server services: [  OK  ]
[root@bigboy tmp]# 

[root@bigboy tmp]# chkconfig portmap on
[root@bigboy tmp]# chkconfig yppasswdd on
[root@bigboy tmp]# chkconfig ypserv on

Table 30.1 lists a summary of the daemon’s functions.

Table 30-1 Required NIS Server Daemons

Daemon Name Purpose
portmap The foundation RPC daemon upon which NIS runs.
yppasswdd Lets users change their passwords on the NIS server from NIS clients
ypserv Main NIS server daemon
ypbind Main NIS client daemon
ypxfrd Used to speed up the transfer of very large NIS maps

Make sure they are all running before continuing to the next step. You can use the rpcinfo command to do this.

[root@bigboy tmp]# rpcinfo -p localhost
   program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper
    100009    1   udp    681  yppasswdd
    100004    2   udp    698  ypserv
    100004    1   udp    698  ypserv
    100004    2   tcp    701  ypserv
    100004    1   tcp    701  ypserv
[root@bigboy tmp]#

The ypbind and ypxfrd daemons won’t start properly until after you initialize the NIS domain. You’ll start these daemons after initialization is completed.

Initialize Your NIS Domain

Now that you have decided on the name of the NIS domain, you’ll have to use the ypinit command to create the associated authentication files for the domain. You will be prompted for the name of the NIS server, which in this case is bigboy.

With this procedure, all nonprivileged accounts are automatically accessible via NIS.

[root@bigboy tmp]# /usr/lib/yp/ypinit -m
At this point, we have to construct a list of the hosts which will run NIS
servers.  bigboy is in the list of NIS server hosts.  Please continue to add
the names for the other hosts, one per line.  When you are done with the
list, type a <control D>.
        next host to add:  bigboy
        next host to add:
The current list of NIS servers looks like this:


Is this correct?  [y/n: y]  y
We need a few minutes to build the databases...
Building /var/yp/NIS-SCHOOL-NETWORK/ypservers...
Running /var/yp/Makefile...
gmake[1]: Entering directory `/var/yp/NIS-SCHOOL-NETWORK'
Updating passwd.byname...
Updating passwd.byuid...
Updating group.byname...
Updating group.bygid...
Updating hosts.byname...
Updating hosts.byaddr...
Updating rpc.byname...
Updating rpc.bynumber...
Updating services.byname...
Updating services.byservicename...
Updating netid.byname...
Updating protocols.bynumber...
Updating protocols.byname...
Updating mail.aliases...
gmake[1]: Leaving directory `/var/yp/NIS-SCHOOL-NETWORK'

bigboy has been set up as a NIS master server.

Now you can run ypinit -s bigboy on all slave server.
[root@bigboy tmp]#

Note: Make sure portmap is running before trying this step or you’ll get errors, such as:

failed to send 'clear' to local ypserv: RPC: Port mapper failureUpdating group.bygid...

You will have to delete the /var/yp/NIS-SCHOOL-NETWORK directory and restart portmap, yppasswd, and ypserv before you’ll be able to do this again successfully.

Start The ypbind and ypxfrd Daemons

You can now start the ypbind and the ypxfrd daemons because the NIS domain files have been created.

[root@bigboy tmp]# service ypbind start
Binding to the NIS domain: [  OK  ]
Listening for an NIS domain server.
[root@bigboy tmp]# service ypxfrd start
Starting YP map server: [  OK  ]
[root@bigboy tmp]# chkconfig ypbind on
[root@bigboy tmp]# chkconfig ypxfrd on

Make Sure The Daemons Are Running

All the NIS daemons use RPC port mapping and, therefore, are listed using the rpcinfo command when they are running correctly.

[root@bigboy tmp]# rpcinfo -p localhost
    program vers proto   port
     100000    2   tcp    111  portmapper
     100000    2   udp    111  portmapper
     100003    2   udp   2049  nfs
     100003    3   udp   2049  nfs
     100021    1   udp   1024  nlockmgr
     100021    3   udp   1024  nlockmgr
     100021    4   udp   1024  nlockmgr
     100004    2   udp    784  ypserv
     100004    1   udp    784  ypserv
     100004    2   tcp    787  ypserv
     100004    1   tcp    787  ypserv
     100009    1   udp    798  yppasswdd
  600100069    1   udp    850  fypxfrd
  600100069    1   tcp    852  fypxfrd
     100007    2   udp    924  ypbind
     100007    1   udp    924  ypbind
     100007    2   tcp    927  ypbind
     100007    1   tcp    927  ypbind
[root@bigboy tmp]#

Adding New NIS Users

New NIS users can be created by logging into the NIS server and creating the new user account. In this case, you’ll create a user account called nisuser and give it a new password.

Once this is complete, you then have to update the NIS domain’s authentication files by executing the make command in the /var/yp directory.

This procedure makes all NIS-enabled, nonprivileged accounts become automatically accessible via NIS, not just newly created ones. It also exports all the user’s characteristics stored in the /etc/passwd and /etc/group files, such as the login shell, the user’s group, and home directory.

[root@bigboy tmp]# useradd -g users nisuser
[root@bigboy tmp]# passwd nisuser
Changing password for user nisuser.
New password:
Retype new password:
passwd: all authentication tokens updated successfully.
[root@bigboy tmp]# cd /var/yp
[root@bigboy yp]# make
gmake[1]: Entering directory `/var/yp/NIS-SCHOOL-NETWORK'
Updating passwd.byname...
Updating passwd.byuid...
Updating netid.byname...
gmake[1]: Leaving directory `/var/yp/NIS-SCHOOL-NETWORK'
[root@bigboy yp]#

You can check to see if the user’s authentication information has been updated by using the ypmatch command, which should return the user’s encrypted password string.

[root@bigboy yp]# ypmatch nisuser passwd
[root@bigboy yp]

You can also use the getent command, which has similar syntax. Unlike ypmatch, getent doesn’t provide an encrypted password when run on an NIS server, it just provides the user’s entry in the /etc/passwd file. On a NIS client, the results are identical with both showing the encrypted password.

[root@bigboy yp]# getent passwd nisuser
[root@bigboy yp]#

Configuring The NIS Client

Now that the NIS server is configured, it’s time to configure the NIS clients. There are a number of related configuration files that you need to edit to get it to work. Take a look at the procedure.

Run authconfig

The authconfig or the authconfig-tui program automatically configures your NIS files after prompting you for the IP address and domain of the NIS server.

[root@smallfry tmp]# authconfig-tui

Once finished, it should create an /etc/yp.conf file that defines, amongst other things, the IP address of the NIS server for a particular domain. It also edits the /etc/sysconfig/network file to define the NIS domain to which the NIS client belongs.

# /etc/yp.conf - ypbind configuration file
domain NIS-SCHOOL-NETWORK server


In addition, the authconfig program updates the /etc/nsswitch.conf file that lists the order in which certain data sources should be searched for name lookups, such as those in DNS, LDAP, and NIS. Here you can see where NIS entries were added for the important login files.

passwd:     files nis
shadow:     files nis
group:      files nis

Note: You can also locate a sample NIS nsswitch.conf file in the /usr/share/doc/yp-tools* directory.

Start The NIS Client Related Daemons

Start the ypbind NIS client, and portmap daemons in the /etc/init.d directory and use the chkconfig command to ensure they start after the next reboot. Remember to use the rpcinfo command to ensure they are running correctly.

[root@smallfry tmp]# service portmap start
Starting portmapper: [  OK  ]
[root@smallfry tmp]# service ypbind start
Binding to the NIS domain:
Listening for an NIS domain server.
[root@smallfry tmp]#

[root@smallfry tmp]# chkconfig ypbind on
[root@smallfry tmp]# chkconfig portmap on

Note: Remember to use the rpcinfo -p localhost command to make sure they all started correctly.

Verify Name Resolution

As the configuration examples refer to the NIS client and server by their hostnames, you’ll have to make sure the names resolve correctly to IP addresses. This can be configured either in DNS, when the hosts reside in the same domain, or more simply by editing the /etc/hosts file on both Linux boxes.

# File: /etc/hosts (smallfry)
#    bigboy

# File: /etc/hosts (bigboy)
#    smallfry

Test NIS Access To The NIS Server

You can run the ypcat, ypmatch, and getent commands to make sure communication to the server is correct.

[root@smallfry tmp]# ypcat passwd
[root@smallfry tmp]#

[root@smallfry tmp]# ypmatch nisuser passwd
[root@smallfry tmp]#

[root@smallfry tmp]# getent passwd nisuser
[root@smallfry tmp]#

Possible sources of error would include:

  • Incorrect authconfig setup resulting in errors in the /etc/yp.conf, /etc/sysconfig/network and /etc/nsswitch.conf files
  • Failure to run the ypinit command on the NIS server
  • NIS not being started on the NIS server or client.
  • Poor routing between the server and client, or the existence of a firewall that’s blocking traffic

Try to eliminate these areas as sources of error and refer to the syslog /var/log/messages file on the client and server for entries that may provide additional clues.

Test Logins via The NIS Server

Once your basic NIS functionality testing is complete, try to test a remote login. Failures in this area could be due to firewalls blocking TELNET or SSH access and the TELNET and SSH server process not being started on the clients.

Logging In Via Telnet

Try logging into the NIS client via telnet if it is enabled

[root@bigboy tmp]# telnet
Connected to
Escape character is '^]'.
Red Hat Linux release 9 (Shrike)
Kernel 2.4.20-6 on an i686
login: nisuser
Last login: Sun Nov 16 22:03:51 from
[nisuser@smallfry nisuser]$

Logging In Via SSH

Try logging into the NIS client via SSH.

[root@bigboy tmp]# ssh -l nisuser
nisuser@'s password:
[nisuser@smallfry nisuser]$

In some versions of Linux, the NIS client’s SSH daemon doesn’t re-read the /etc/nsswitch.conf file you just modified until SSH is restarted. SSH logins, therefore, won’t query the NIS server until this is done. Restart SSH on the NIS client.

[root@smallfry root]# service sshd restart
Stopping sshd:[  OK  ]
Starting sshd:[  OK  ]
[root@smallfry root]#

Original Post from : linuxhomenetworking

8 Responses to “NIS Domain”

  1. dipmit January 17, 2010 at 10:46 am #

    hi this is dipmit pandya
    i want to know about RIS there is no any information in your web site for this topic
    so please help me to clear this topic and configuration about this

  2. Vishal January 18, 2010 at 7:35 am #

    hi dipmit pls give me your mail id.

  3. alex June 14, 2011 at 4:16 pm #

    yeh is graet but i no work my the userid map nos is propertry loader

    id: cannot find name for user ID
    I have no name!@……


  4. Waqas June 23, 2013 at 6:04 pm #

    Hi Vishal. Kep up the good work. Really nice information and in a good way as well.

  5. hemanth September 7, 2013 at 8:45 am #

    namaskar guruji. i want to configure ldap server and client in centos 6.4 with TLS and i want to know how to access ldap server through windows client and centos 6.4 client.and also i need how to check the user details(what ever client has done ) in ldap server.

    • sandeep October 8, 2015 at 7:48 am #

      Iam also looking for that configuration in detailed how to configure ldap for the windows client

  6. Manpreet Gill July 8, 2014 at 12:16 pm #

    very good and clear doc.

  7. n/a/ December 10, 2014 at 9:47 pm #

    Pretty! This was an incredibly wonderful article.
    Many thanks for supplying these details.

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