libnss-pgsql - Name Service Switch module for use with PostgreSQL
Chapter 2 Module and Database Setup

2.1 required database structure

To use this module with a database you will need at least three tables in that database. One for account data (the information usually stored in /etc/passwd), one for group data (/etc/group) and another one storing information about groupmembership (there is a m:n relation between passwd and group so you need this weak entity). If you have an existing database you do not want to modify you can use views or table expressions (see Confile File, Section A.2), of course.

2.1.1 tables and fields

There have to be some required fields in those tables. They are described below.

passwd table (see getpwnam(3) for more information)

• login name
• password
• numerical user id (uid)
• numerical primary group id (gid)
• login shell
• description (gecos)
• home directory

group table (see getgrnam(3))

• group name
• group password
• numerical group id (gid)

An example database schema can be found in Database Schema, Section A.1. See there for how to construct the groupmember table.

2.2 configuring the module

Having a working database, you must write your configfile /etc/nss-pgsql.conf. This file has a simple syntax:

     LINE      := COMMENT | EMPTY | STATEMENT
     COMMENT   := '#' <text>
     EMPTY     := ''
     STATEMENT := KEYWORD '=' <value>

With KEYWORD being one of the following (all are required):

host

Hostname or IP address of PostgreSQL server.

port

Port on which the Postmaster listens.

database

The database name.

login

Username for logging in to the PostgreSQL server.

passwd

Password for logging in.

passwdtable

Name of the table storing the account data.

grouptable

Table storing group data.

groupmembertable

Table storing the 'links' between account and group data.

passwd_name

Name of field in passwdtable storing the user name.

passwd_passwd

Field storing the password.

passwd_uid

Field storing the numerical user id.

passwd_dir

Field storing the $HOME directory.

passwd_shell

Field storing the user's shell.

passwd_gecos

Field storing additional information about this user, e.g. his full name and phone number.

passwd_gid

Field storing the numerical primary group id.

group_name

Name of the field in grouptable storing the group name.

group_passwd

Field storing the groups password.

group_gid

Field storing the group id.

group_member

Name of field in groupmembertable storing the user name being member of the queried group.