Chapter 21. Using NIS

Contents

21.1. Configuring NIS Servers
21.2. Configuring NIS Clients

Abstract

As soon as multiple UNIX systems in a network want to access common resources, it becomes important that all user and group identities are the same for all machines in that network. The network should be transparent to users: whatever machines they use, they always find themselves in exactly the same environment. This is made possible by means of NIS and NFS services. NFS distributes file systems over a network and is discussed in Chapter 22, Sharing File Systems with NFS.

NIS (Network Information Service) can be described as a database-like service that provides access to the contents of /etc/passwd, /etc/shadow, and /etc/group across networks. NIS can also be used for other purposes (making the contents of files like /etc/hosts or /etc/services available, for example), but this is beyond the scope of this introduction. People often refer to NIS as YP, because it works like the network's “yellow pages.


21.1. Configuring NIS Servers

To distribute NIS information across networks, you can either have one single server (a master) that serves to all clients or you can have NIS slave servers request this information from the master then relay it to their respective clients.

21.1.1. Configuring a NIS Master Server

To configure a NIS master server for your network, proceed as follows:

  1. Start YaST+Network Services+NIS Server.

  2. If you need just one NIS server in your network or if this server is to act as the master for further NIS slave servers, select Install and set up NIS Master Server. YaST installs the required packages.

    [Tip]Tip

    If NIS server software is already installed on your machine, initiate the creation of a NIS master server by clicking Create NIS Master Server.

    Figure 21.1. NIS Server Setup

    NIS Server Setup
  3. Determine basic NIS setup options:

    1. Enter the NIS domain name.

    2. Define whether the host should also be a NIS client, enabling users to log in and access data from the NIS server, by selecting This host is also a NIS client.

      Select Changing of passwords to allow users in your network (both local users and those managed through the NIS server) to change their passwords on the NIS server (with the command yppasswd).

      This makes the options Allow Changes to GECOS Field and Allow Changes to Login Shell available. “GECOS” means that the users can also change their names and address settings with the command ypchfn. “SHELL” allows users to change their default shell with the command ypchsh, for example, to switch from bash to sh. The new shell must be one of the predefined entries in /etc/shells.

    3. If your NIS server should act as a master server to NIS slave servers in other subnets, select Active Slave NIS Server exists.

    4. Select Open Ports in Firewall to have YaST adapt the firewall settings for the NIS server.

      Figure 21.2. Master Server Setup

      Master Server Setup
    5. Leave this dialog with Next or click Other global settings to make additional settings. Other global settings include changing the source directory of the NIS server (/etc by default). In addition, passwords can be merged here. The setting should be Yes so the files (/etc/passwd, /etc/shadow, and /etc/group) are used to build the user database. Also determine the smallest user and group ID that should be offered by NIS. Click OK to confirm your settings and return to the previous screen.

      Figure 21.3. Changing the Directory and Synchronizing Files for a NIS Server

      Changing the Directory and Synchronizing Files for a NIS Server
  4. If you previously enabled Active Slave NIS Server Exists, enter the hostnames used as slaves and click Next.

  5. If you do not use slave servers, the slave configuration is skipped and you continue directly to the dialog for the database configuration. Here, specify the maps, the partial databases to transfer from the NIS server to the client. The default settings are usually adequate. Leave this dialog with Next.

  6. Check which maps should be available and click Next to continue.

    Figure 21.4. NIS Server Maps Setup

    NIS Server Maps Setup
  7. Enter the hosts that are allowed to query the NIS server. You can add, edit, or delete hosts by clicking the appropriate button. Specify from which networks requests can be sent to the NIS server. Normally, this is your internal network. In this case, there should be the following two entries:

    255.0.0.0     127.0.0.0
    0.0.0.0       0.0.0.0
         

    The first entry enables connections from your own host, which is the NIS server. The second one allows all hosts to send requests to the server.

    Figure 21.5. Setting Request Permissions for a NIS Server

    Setting Request Permissions for a NIS Server
  8. Click Finish to save changes and exit the setup.

21.1.2. Configuring a NIS Slave Server

To configure additional NIS slave servers in your network, proceed as follows:

  1. Start YaST+Network Services+NIS Server.

  2. Select Install and set up NIS Slave Server and click Next.

    [Tip]Tip

    If NIS server software is already installed on your machine, initiate the creation of a NIS slave server by clicking Create NIS Slave Server.

  3. Complete the basic setup of your NIS slave server:

    1. Enter the NIS domain.

    2. Enter hostname or IP address of the master server.

    3. Set This host is also a NIS client if you want to enable user logins on this server.

    4. Adapt the firewall settings with Open Ports in Firewall.

    5. Click Next.

  4. Enter the hosts that are allowed to query the NIS server. You can add, edit, or delete hosts by clicking the appropriate button. Specify from which networks requests can be sent to the NIS server. Normally, this is all hosts. In this case, there should be the following two entries:

    255.0.0.0     127.0.0.0
    0.0.0.0       0.0.0.0
         

    The first entry enables connections from your own host, which is the NIS server. The second one allows all hosts with access to the same network to send requests to the server.

  5. Click Finish to save changes and exit the setup.