Acronym for Name Service Switch

The NSS is a glibc mechanism for providing multiple methods of accessing common databases such as the password or hosts database. It is commonly used to provide an interface to both local /etc/passwd (and shadow) files, and a remote authentication mechanism such as NIS or LDAP.

The config file for specifying backend methods for each database is /etc/nsswitch.conf -- see the nsswitch.conf(5) ManPage.

The databases available for configuration within the NSS are:

aliases(5):

Mail aliases

ethers(5):

Ethernet numbers,

group(5):

Groups of users

hosts(5):

Host names and numbers.

netgroup(5)?:

Network wide list of host and users

networks(5):

Network names and numbers

protocols(5):

Network protocols

passwd(5):

User passwords

rpc(5):

Remote procedure call names and numbers,

services(5):

Network services

shadow(5):

Shadow user passwords

Most of these databases are normally only configured for flatfile access: protocols and services, for example, look up only in /etc/protocols and /etc/services. You could serve these from LDAP, or from a DBM? file, or from an SQL DataBase, or so on.

See http://www.delorie.com/gnu/docs/glibc/libc_591.html for more information on the glibc NSS