SQL
===

SQL can be used for both passdb and userdb lookups. If the args parameter in
passdb sql and userdb sql contain the exact same filename, only one SQL
connection is used for both passdb and userdb lookups.

Password database lookups
-------------------------

'password_query' setting contains the SQL query to look up the password. It
must return a field named "password". If you have it by any other name in the
database, you can use the SQL's "AS" keyword ('SELECT pw AS password ..'). You
can use all the normal<variables> [Variables.txt] such as '%u' in the SQL
query.

If all the passwords are in same format, you can use 'default_pass_scheme' to
specify it. Otherwise each password needs to be prefixed with
"{password-scheme}", for example "{plain}plaintext-password".
See<Authentication.PasswordSchemes.txt> for a list of supported password
schemes.

By default MySQL does case-insensitive string comparisons, so you may have a
problem if your users are logging with different as "user", "User" and "uSer".
To fix this, you can make the SQL database return a "user" field, which makes
Dovecot modify the username to the returned value.

Note that if you're using separate user and domain fields, a common problem is
that you're returning only the "user" field from the database.*This drops out
the domain from the username*. So make sure you're returning a concatenated
user@domain string. See the examples below.

The query can also return other <extra fields>
[PasswordDatabase.ExtraFields.txt] which have special meaning.

Password verification by SQL server
-----------------------------------

If the passwords are in some special format in the SQL server that Dovecot
doesn't recognize, it's still possible to use them. Change the SQL query to
return NULL as the password and return the row only if the password matches.
The password is in '%w' variable. For example:

---%<-------------------------------------------------------------------------
# NOTE: '\' line splitting is used only for readability, currently Dovecot
doesn't support it
password_query = SELECT NULL AS password, userid AS user \
  FROM users WHERE userid = '%u' AND mysql_pass = password('%w')
---%<-------------------------------------------------------------------------

This of course makes the verbose logging a bit wrong, since password mismatches
are also logged as "unknown user".

User database lookups
---------------------

Usually your SQL database contains also the userdb information. This means
user's UID, GID and home directory. If you're using only static UID and GID,
and your home directory can be specified with a template, you could use<static
userdb> [UserDatabase.Static.txt] instead. It is also a bit faster since it
avoids doing the userdb SQL query.

'user_query' setting contains the SQL query to look up the userdb information.
The commonly returned userdb fields are uid, gid, home and mail.
See<UserDatabase.ExtraFields.txt> for more information about these and other
fields that can be returned.

If you're using a single UID and GID for all users, you can use a SQL query
such as:

---%<-------------------------------------------------------------------------
user_query = SELECT 500 AS uid, 500 AS gid, home FROM users WHERE userid = '%n'
---%<-------------------------------------------------------------------------

Prefetching
-----------

If you want to avoid doing two SQL queries when logging in with IMAP/POP3, you
can make the 'password_query' return all the necessary userdb fields and use
prefetch userdb to use those fields. If you're using Dovecot's deliver you'll
still need to have the 'user_query' working.

See <UserDatabase.Prefetch.txt> for example configuration

Example
-------

Note that "user" can have a special meaning in some SQL databases, so we're
using "userid" instead.

SQL table creation command:

---%<-------------------------------------------------------------------------
CREATE TABLE users (
    userid VARCHAR(128) NOT NULL,
    domain VARCHAR(128) NOT NULL,
    password VARCHAR(64) NOT NULL,
    home VARCHAR(255) NOT NULL,
    uid INTEGER NOT NULL,
    gid INTEGER NOT NULL
);
---%<-------------------------------------------------------------------------

MySQL
-----

dovecot-sql.conf:

---%<-------------------------------------------------------------------------
# NOTE: '\' line splitting is used only for readability, currently Dovecot
doesn't support it
# The mysqld.sock socket may be in different locations in different systems
driver = mysql
connect = host=/var/run/mysqld/mysqld.sock dbname=mails user=admin
password=pass
# Alternatively you can connect to localhost as well:
#connect = host=localhost dbname=mails user=admin password=pass
password_query = SELECT concat(userid, '@', domain) AS user, password \
  FROM users WHERE userid = '%n' AND domain = '%d'
user_query = SELECT home, uid, gid FROM users WHERE userid = '%u'
---%<-------------------------------------------------------------------------

PostgreSQL
----------

dovecot-sql.conf:

---%<-------------------------------------------------------------------------
# NOTE: '\' line splitting is used only for readability, currently Dovecot
doesn't support it
# You can also set up non-password authentication by modifying PostgreSQL's
pg_hba.conf
driver = pgsql
connect = host=localhost dbname=mails user=admin password=pass
# PostgreSQL:
password_query = SELECT userid || '@' || domain AS user, password \
  FROM users WHERE userid = '%n' AND domain = '%d'
user_query = SELECT home, uid, gid FROM users WHERE userid = '%u'
---%<-------------------------------------------------------------------------

(This file was created from the wiki on 2008-06-20 04:42)
