Naming Services

The information handled by a name service includes the following:

• System (host) names and addresses

• Usernames

• Passwords

• Access permissions

Table 35 describes the name services available in Solaris 10.

Table 35. Name Services

Name Service	Description
/etc files	The original Unix naming system.
NIS	The Network Information Service.
NIS+	The Network Information Service Plus.
DNS	The Domain Name System.
LDAP	Lightweight Directory Access Protocol.

/etc Files

/etc files are the traditional Unix way of maintaining information about hosts, users, passwords, groups, and automount maps, to name just a few. These files are text files located on each individual system that can be edited using the vi editor or the text editor within CDE.

NIS

The NIS, formerly called the Yellow Pages (YP), is a distributed database system that allows the system administrator to administer the configuration of many hosts from a central location. Common configuration information, which would have to be maintained separately on each host in a network without NIS, can be stored and maintained in a central location, and then propagated to all the nodes in the network. NIS stores information about workstation names and addresses, users, the network itself, and network services.

The systems within an NIS network are configured in the following ways:

• Master server

• Slave servers

• Clients of NIS servers

The name service switch controls how a client workstation or application obtains network information. Each workstation has a name service switch file in its /etc directory. In every system's /etc directory, you'll find templates for the nsswitch.conf file. These templates are described in Table 36.

Table 36. Name Service Switch Template Files

Name	Description
nsswitch.files	This template file is used when local files in the /etc directory are to be used and no name service exists.
nsswitch.nis	This template file uses the NIS database as the primary source of all information except the passwd, group, automount, and aliases maps. These are directed to use the local /etc files first, and then the NIS databases.
nsswitch.nisplus	This template file uses the NIS+ database as the primary source of all information except the passwd, group, automount, and aliases tables. These are directed to use the local /etc files first, and then the NIS+ databases.
nsswitch.dns	This template file searches the local /etc files for all entries except the hosts enTRy. The hosts enTRy is directed to use DNS for lookup.
nsswitch.ldap	This template file uses LDAP as the primary source of all information except the passwd, group, automount, and aliases tables. These are directed to use the local /etc files first, and then the LDAP databases.

The name service switch file contains a list of more than 19 types of network information, called databases, with their name service sources for resolution and the order in which the sources are to be searched. Table 37 lists valid sources that can be specified in this file.

Table 37. Database Sources for Services in /etc/nsswitch.conf

Source	Description
files	Refers to the client's local /etc files
nisplus	Refers to an NIS+ table
nis	Refers to an NIS table
user	Applies to printers only and specifies that printer information be obtained from the ${HOME}/.printers file
dns	Applies only to the hosts entry
ldap	Refers to a dictionary information tree (DIT)
compat	Supports an old style [+] syntax that was used in the passwd and group information

NIS+

NIS+ is similar to NIS, but with more features. NIS+ is not an extension of NIS, but a new system. It was designed to replace NIS.

NIS addresses the administrative requirements of small-to-medium client/server computing networksthose with less than a few hundred clients. Some sites with thousands of users find NIS adequate as well. NIS+ is designed for the now-prevalent larger networks in which systems are spread across remote sites in various time zones and in which clients number in the thousands. In addition, the information stored in networks today changes much more frequently, and NIS had to be updated to handle this environment. Lastly, systems today require a high level of security, and NIS+ addresses many security issues that NIS did not.

Remember that NIS+ is being discontinued and will not be part of a future Solaris release.

DNS

DNS is the name service used by the Internet and other Transmission Control Protocol/Internet Protocol (TCP/IP) networks. It was developed so that workstations on the network could be identified by common names instead of numerical Internet addresses. DNS is a program that converts domain names to their IP addresses. Without it, users have to remember numbers instead of words to get around the Internet. The process of finding a computer's IP address by using its hostname as an index is referred to as name-to-address resolution, or mapping.

Lightweight Directory Access Protocol (LDAP)

LDAP is the latest name-lookup service to be added to Solaris and is expected to replace NIS and NIS+ in the future. Specifically, LDAP is a directory service. A directory service is like a database, but tends to contain more descriptive, attribute-based information. The information in a directory is generally read, not written.