Support to authenticate against PostgreSQL for PAM-enabled appliations
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Add support installation information for installing on CentOS 7.
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README

pam_pgsql 0.7
=============

Introduction
============

This module provides support to authenticate against PostgreSQL
tables for PAM-enabled appliations.

This module is based in part on the FreeBSD pam_unix module, and
the Debian pam_mysql module, but was written from scratch using
the two as a reference.

There is another pam_pgsql module, but the sources appear to have
vanished, hence this module.

Changes since last release
==========================

See the file CHANGELOG.

Compilation & Installation
==========================

pam_pgsql is now autoconf'ed, thus, compiling should be a matter
of:

    $ ./configure
    $ make
    $ make install

Or if you're using a git version, run this command before them all:

    $ ./autogen.sh

Compilation has been tested on Debian GNU/Linux, ArchLinux, FreeBSD 7.2 and CentOS 7.

On Debian, you will need the libpam0g-dev and postgresql-dev packages to compile.
On FreeBSD you will have to install the postgresql/postgresql8*-client port.
On CentOS you will have to install `libgcrypt`, `postgresql-devel` and `libgcrypt-devel` installed, as well as `gcc-c++`. Then autoreconf with:

    $ autoreconf --install

once that done, you can now `./configure`, `make` and `make install`.

See authenticate.c and chpass.c for an example application that authenticates and change password using this module.

This version only works with PostgreSQL versions 7.4 or newer.

Configuration
=============

For the service you wish the module to be used, you need
to edit the /etc/pam.d/<service> file or /etc/pam.conf, and 
add the relevant lines.

For example:

auth        required    pam_pgsql.so 
account     required    pam_pgsql.so
password    required    pam_pgsql.so
session     required    pam_pgsql.so

Or:

password    required    pam_cracklib.so
password    required    pam_pgsql.so authtok

Configure the database, and table the module should use with
the configuration file /etc/pam_pgsql.conf. An example of
this file:

database = sysdb
user = ljb
table = account
user_column = user_name
pwd_column = user_password
expired_column = acc_expired
newtok_column = acc_new_pwreq
debug = 1

Note that for backwards compatibility with earlier versions, options specified
in the configuration file can be supplied as module arguments as well. Module
arguments will override the configuration file.

From version 0.6 you can also use new style configuration (overrides legacy
values).

connect = dbname=sysdb user=ljb password=sth connect_timeout=15
auth_query = select user_password from account where user_name = %u
acct_query = select (acc_expired = 'y' OR acc_expired = '1'), (acc_new_pwreq = 'y' OR acc_new_pwreq = '1'), (user_password IS NULL OR user_password = '') from account where user_name = %u
pwd_query = update account set user_password = %p where user_name = %u


Configuration Options
=====================

    connect 		- the database connection string (see http://www.postgresql.org/docs/7.4/interactive/libpq.html#LIBPQ-CONNECT)
			  overrides other connection specific options
    auth_query		- authentication query (should return one column -- password)
			  overrides other authentication specific options
    auth_succ_query	- query to be executed after successful authentication
    auth_fail_query	- query to be executed after failed authentication
    session_open_query  - query to be executed on session start
    session_close_query - query to be executed on session end

    acct_query		- account options query (should return 3 or 4 boolean columns -- expired, new password required and password is null, return PAM_PERM_DENIED (y/n))
			  overrides other account specific options
    pwd_query		- query to be executed for password changing 
			  overrides other settings related to changing password

You can use %u as username, %p as (new) password, %h for hostname of client
as specified by PAM subsystem, %i for IP got by gethostbyname(%h) and %s as
pa service name in any query. Please don't forget to specify pw_type as %p
is replaced by password of pw_type form.

Caution: 
If %h is unavailable but used, system substitutes it in query with
NULL, but does not fail (you can fail it manually by using "%s is not null"
somewhere in your query). If %i is used and gethostbyname() fails than:
	(i) when rhost is empty or doesn't contain any periods ("."), %i is
replaced with NULL
	(ii) in any other case pam_pgsql return PAM_AUTH_ERR. 

    database            - the database which should be connected to
    table               - the table containing the authentication data
    host		- the host database server is running on (leave empty for socket)
    port		- the port database server is running on (leave empty for socket)
    user                - the username used when connecting to PostgreSQL
    password            - the password for the user specified
    user_column         - the column containing usernames
    pwd_column          - the column containing the passwords
    expired_column      - this column should contain '1' or 'y' if the account
                          has expired, bool type is OK
    newtok_column       - this column should contain '1' or 'y' if the user
                          needs to change their password, bool type is OK
    debug               - this is a standard module option that will enable
                          debug output to syslog (takes no values)
    pw_type             - specifies the password encryption scheme, can be one
                          of 'clear', 'md5', 'sha1', 'crypt', 'crypt_md5',
						  'md5_postgres' or 'function'. The difference between 'md5' and
						  'crypt_md5' is that 'md5' uses libmhash for hashing
						  while 'crypt_md5' uses crypt() with a special salt to
						  select md5 hashing instead of DES. if one of 'crypt'
						  or 'crypt_md5' is specified, passwords always are
                          encrypted in the respective format. however,
                          passwords in both formats may be stored in the
                          database, just as with /etc/(passwd|shadow).
                          'function' means to use a database function to generate
                          the hash, and authenticate the user. In that case the 'auth_query'
                          should return a boolean value. defaults to 'clear'.
						  'md5_postgres' uses the postgres default internal
						  algorithm where hash is md5||md5(password+login). This
						  is usefull for authenticating against postgres users
						  created by the createuser postgres command.
    config_file         - alternative location of configuration file - it should be
			  specified as module argument.
    timeout		- if specified pam-pgsql will wait for timeout
			  seconds before giving up on db connection

There are also additional flags you can use:
    authtok		- see "use_first_pass"
    use_first_pass	- require authtok from previous entry in PAM stack
			  (useful for "password   required  pam_pgsql.so authtok")
			  after "password required pam_cracklib.so ..."
    try_first_pass	- same as previous, but doesn't fail if previous
			  module failed to provide us with password
    echo_pass 		- displays password while being typed

Example to autenticate against postgres users
=============================================
database = postgres
user = postgres
table = pg_catalog.pg_shadow
user_column = usename
pwd_column = passwd
pw_type=md5_postgres