NIS+

NIS+ is a directory service developed by Sun Microsystems to replace its older 'NIS' (Network Information Service). It is designed to eliminate the need for duplication across many computers of configuration data such as user accounts, host names and addresses, printer information and NFS disk mounts on individual systems, instead using a central repository on a master server, simplifying system administration. NIS+ client software has been ported to other Unix and Unix-like platforms.

Prior to the release of Solaris 9 in 2002, Sun announced its intent to remove NIS+ from Solaris in a future release and now recommends that customers instead use an LDAP-based lookup scheme. NIS+ was present in Solaris 9 and 10 (although both releases include tools to migrate NIS+ data to an LDAP server)^[1] and it has now been removed from the OpenSolaris trunk.^[2]

NIS vs. NIS+

NIS and NIS+ are only similar in their purpose and name; otherwise, they have completely different implementations. They differ in the following ways:

• NIS+ is hierarchical.
• NIS+ is based around Secure RPC (servers must authenticate clients and vice-versa).
• NIS+ may be replicated (replicas are read-only).
• NIS+ implements permissions on directories, tables, columns and rows.
• NIS+ also implements permissions on operations, such as being able to use nisping to transfer changed data from a master to a replica.

The problem of managing network information

In the 1970s, when computers were expensive and networks consisted of a few nodes, administering network information for a few nodes was manageable and a centralized system was not needed. As computers became cheaper and networks grew larger, it became increasingly more difficult to maintain separate copies of network configurations on every individual system.

For example, whenever a new user was added to the network, the following files would need to be updated on every existing system:

File	Sample entry	Information
/etc/passwd	numiri:x:37:4:Sebastian Nguyen:/home/numiri	user name, home directory, ...
/etc/shadow	numiri:1AD3ioUMlkj234k:	encrypted password

Likewise /etc/group would have needed updating every time a new group was added and /etc/hosts would have needed updating every time a new computer was added to the network.

If a new user with a new system is added to a network of 20 existing systems, the UNIX administrator would need to modify 5 files on 21 machines, or 105 files in all. With NIS+, adding user and machines to the network only requires changes to the NIS+ server's maps and the new host’s /etc/nsswitch.conf needs to point to the NIS+ server. When a user logs into any other machine, that host (the NIS+ client), knowing who the NIS+ server is, queries it for the username and password to identify and authenticate the user.

NIS+ also manages several other types of data: NFS mounts (auto_master, auto_home), network booting and other parameters (bootparams, ethers, netmasks, netgroup, networks, protocols, rpc, services), security access (cred), aliases, and timezone.

An installation of NIS+ comes with such table structures predefined. There are facilities available to create other tables as needed.

Alternatives

Other alternative schemes for storing network information exist, such as the LDAP standard maintained by the IETF, including Microsoft’s LDAP implementation, Active Directory. LDAP can be configured to handle more general information, such as corporate employee structures, phone numbers, address, etc. so it requires more thought and planning. Many organizations require all the features of NIS+, LDAP, and Active Directory and run them all simultaneously.

Another alternative that has been popular in certain environments is the Hesiod name service, which is based on the DNS protocols.

NIS+ client/server model

Unlike NIS, NIS+ uses a hierarchical structure of multiple domains. A NIS+ domain can, and should, be serviced by multiple servers. The primary server is known as the master server, and backup servers are known as replica servers. Both types hold copies of the NIS+ tables. Changes are first committed to the master server and then propagated to replica servers in increments.

NIS+ table permissions determine a user's level of access to the table's contents.

See also

• client–server model
• Lightweight Directory Access Protocol (LDAP)
• Network Information Service (NIS)

References

1. ^ "NIS+ End-of-Feature (EOF) Announcement FAQ". Sun Microsystems. http://www.sun.com/software/solaris/faqs/nisplus.xml. Retrieved 2007-06-04. 
2. ^ Bug ID: 6874309 Remove NIS+ from Solaris (OpenSolaris bug database)

External links

• NIS+ FAQs
• NIS+ installation and Configuration
• Resources on how to replace NIS and NIS+ can be found at the NIS Migration Resource Site