
If you never heard about MySQL before, *DON'T* enable MySQL support in
Pure-FTPd. MySQL is useless if you don't have to manage many shared
accounts. But well... if you want to learn about MySQL anyway, here's a good
starting point: http://www.mysql.com/ .


       ------------------------ MYSQL SUPPORT ------------------------


Since release 0.99.1, Pure-FTPd has a built-in support for MySQL databases.
When MySQL is enabled, all account info is fetched from a central MySQL
database.

To compile the server with MySQL support, you first have to build and
install the MySQL client libraries. MySQL is freely available from
http://www.mysql.com/ and binary packages are included in many major
distributions. But if you choose a binary form, don't forget to also install
the development packages if they are available separately.

Then, configure Pure-FTPd with --with-mysql and your favorite extra gadgets:


    ./configure --with-mysql --with-cookie --with-throttling --with-ratios


If your MySQL libraries are installed in a special path, you can specify it
like this:


    ./configure --with-mysql=/opt/mysql


In this example, headers (like mysql.h) will be searched in
/opt/mysql/include and /opt/mysql/include/mysql, while related libraries
will be searched in /opt/mysql/lib and /opt/mysql/lib/mysql .

Then, install the server as usual:


                                 make install


 ------------------------ MYSQL CONFIGURATION FILE ------------------------
           

Before running the server, you have to create a configuration file. Why a
configuration file instead of simple command-line options? you may ask.
Because for security reasons, you may want to hide how to connect to your
MySQL server. And as command-line options can be discovered by local users
(with 'ps auxwww' for instance), it's more secure to use a configuration
file for sensitive data. Keep it readable only by root (chmod 600) .

Here's a sample configuration file:

#MYSQLServer     localhost
#MYSQLPort       3306
MYSQLSocket     /tmp/mysql.sock
MYSQLUser       root
MYSQLPassword   rootpw
MYSQLDatabase   pureftpd
MYSQLCrypt      cleartext
MYSQLGetPW      SELECT Password FROM users WHERE User="\L"
MYSQLGetUID     SELECT Uid FROM users WHERE User="\L"
MYSQLGetGID     SELECT Gid FROM users WHERE User="\L"
MYSQLGetDir     SELECT Dir FROM users WHERE User="\L"

Have a look at the sample pureftpd-mysql.conf configuration file for
explanations of every keyword.

Save the configuration file anywhere. Let's say /etc/pureftpd-mysql.conf .

Then, you have to run the pure-ftpd command with '-l mysql:' (it's an 'ell'
not a 'one') followed by the path of that configuration file. Here's an
example with tcpserver:


tcpserver -DHRl0 0 21 /usr/local/bin/pure-ftpd -l mysql:/etc/pureftpd-mysql.conf &


You can mix different authentication methods. For instance, if you want to
use system (/etc/passwd) accounts when an account is not found in a MySQL
database, use -l mysql:/etc/pureftpd-mysql.conf -l unix


     ------------------------ TABLES STRUCTURES ------------------------
     
     
Pure-FTPd is very flexible and users can be stored in any way in SQL tables.
You just have to have fields with the following info:

- The user's login.

- The user's password, in plaintext, MD5, crypt()ed or MySQL's password()
format. Pure-FTPd also accepts the "any" value for the MySQLCrypt field.
With "any", all hashing functions (not plaintext) are tried.

* RECOMMENDATION: On Solaris systems and on very old C libraries, use MySQL
MD5 hashing. On all other systems, better use crypt(), which adds a salt.
Avoid password() whoose hash function is rather weak, not portable, and it is
supposed to be only used for internal accounts of MySQL servers. password() is
no more supported by Pure-FTPd with MySQL 4.1.0 and later.

- The system uid to map the user to. This can be a numeric id or a user
name, looked up at run-time.

- The system gid (numeric or not) .

- The home directory.

Here's a dump of a simple table to handle this:

CREATE TABLE users (
  User VARCHAR(16) BINARY NOT NULL,
  Password VARCHAR(64) BINARY NOT NULL,
  Uid INT(11) NOT NULL default '-1',
  Gid INT(11) NOT NULL default '-1',
  Dir VARCHAR(128) BINARY NOT NULL,
  PRIMARY KEY  (User)
);

Uid and Gid can be char() instead of int() if you want to use names instead
of values.

Then, in the pureftpd-mysql.conf configuration file, you have to provide SQL
templates to fetch the needed info.

Let's take the previous example:

MYSQLGetPW      SELECT Password FROM users WHERE User="\L"
MYSQLGetUID     SELECT Uid FROM users WHERE User="\L"
MYSQLGetGID     SELECT Gid FROM users WHERE User="\L"
MYSQLGetDir     SELECT Dir FROM users WHERE User="\L"

For each query:

\L is replaced by the login of a user trying to authenticate.
\I is replaced by the IP address the client connected to.
\P is replaced by the port number the client connected to.
\R is replaced by the remote IP address the client connected from.
\D is replaced by the remote IPv4 address, as a long decimal number.

You can mix all of these to store info in various tables. For instance, with
\I, you can have a different table for every domain, so that joe@domain1
won't be the same account than joe@domain2 . And with \R, you can restrict
one account to one specific address.

With MySQL 4.1 and later, multiple statements can be used using a semicolumn
(";") as a delimiter.

Please note that a login can only contains common characters: A...Z, a...z,
0...9, -, ., _, space, :, @ and ' . For security purposes, other characters
are forbidden.

You can also remove uid and gid fields in your tables and use default
values instead (thus saving useless lookups) . Two directives are
useful to serve that purpose: MYSQLDefaultUID and MYSQLDefaultGID.

Obvious example:

MYSQLDefaultUID 1000
MYSQLDefaultGID 1000

Using these directives overrides MYSQLGetUID and MYSQLGetGID.


     ------------------------ PER-USER SETTINGS ------------------------


Individual settings can be set for every user, using optional queries.

- MySQLGetQTAFS is the maximal number of files a user can store in his home
directory.

Example:
MySQLGetQTAFS  SELECT QuotaFiles FROM users WHERE User="\L"

- MySQLGetQTASZ is the maximal disk usage, in Megabytes.

Example:
MySQLGetQTASZ  SELECT QuotaSize FROM users WHERE User="\L"

- MySQLGetRatioUL and MySQLGetRatioDL are optional ratios.

Example:
MySQLGetRatioUL SELECT ULRatio FROM users WHERE User="\L"
MySQLGetRatioDL SELECT DLRatio FROM users WHERE User="\L"

- MySQLGetBandwidthUL and MySQLGetBandwidthDL are optional upload and
download bandwidth restrictions. Returned values should be in KB/s.

Example:
MySQLGetBandwidthUL SELECT ULBandwidth FROM users WHERE User="\L"
MySQLGetBandwidthDL SELECT DLBandwidth FROM users WHERE User="\L"

- MySQLForceTildeExpansion is yet another optional feature, to enable "~"
expansion in paths. 0 disables it (default), 1 enables it. Only enable this
if real (system) users and virtual (MySQL) users match. In all other cases,
don't enable it blindly.


       ------------------------ TRANSACTIONS ------------------------


If you upgraded your tables to transaction-enabled tables, you can configure
Pure-FTPd to take advantage of transactions. That way, you can be sure that
all info parsed by the server is complete even if you're updating it at the
same time.

To enable transactions, add this line:

MySQLTransactions On

Don't enable transactions on tables that still are in ISAM or MyISAM
formats. Transactions are only working with newer backends (Gemini, InnoDB,
BerkeleyDB...) and in recent MySQL versions.


     ------------------------ STORED PROCEDURES ------------------------


Mike Goins says:

To get pure-ftp to use a MySQL 5 stored procedure, use statements like:

MYSQLGetDir   CALL get_path_from_name("\L")
instead of
MYSQLGetDir   SELECT user_dir FROM user WHERE user_name="\L"

Note that this requires the type of Stored Procedure that returns a result set
in a single call as opposed to the two call method:
CALL sp('value', @a); SELECT @a


      ------------------------ ANONYMOUS USERS ------------------------


If you want to accept anonymous users on your FTP server, you don't need to
have any 'ftp' user in the MySQL directory. But you need to have a system
'ftp' account on the FTP server.


        ------------------------ ROOT USERS ------------------------


If a MySQL user entry has a root (0) uid and/or gid, Pure-FTPd will refuse
to log him in.

Without this preventive restriction, if your MySQL server ever gets
compromised, the attacker could also easily compromise the FTP server.

Security barriers are also implemented to avoid bad implications if wrong
data types (eg. binary blobs instead of plain text) are fetched with SQL
queries.




          -Frank DENIS <j at pureftpd dot org>.
