ProFTPD module mod_sql

## ProFTPD module `mod_sql`

This module is contained in the `contrib/mod_sql.c`, `contrib/mod_sql.h`, `contrib/mod_sql_mysql.c`, and `contrib/mod_sql_postgres.c` files for ProFTPD 1.2.x/1.3.x, and is not compiled by default. Installation instructions are discussed here.

The `mod_sql` module is an authentication and logging module for ProFTPD. It is comprised of a front end module (`mod_sql`) and backend database-specific modules (`mod_sql_mysql`, `mod_sql_postgres`). The front end module leaves the specifics of handling database connections to the backend modules.

The most current version of `mod_sql` is distributed with ProFTPD.

## Thanks

- Johnie Ingram <johnie at netgod.net> for the original `mod_sqlpw`.
- TJ Saunders and Jesse Sipprell for dealing with my inane questions.
- John Morrissey for `mod_ldap`, which lit the way, here and there.
- Zeev Suraski <bourbon at bourbon.netvision.net.il> for the Apache `mod_auth_mysql` module, which informed the `SQLAuthTypes` directive.
- Avalon from IRC for doc-fixes and suggestions.
- and many others who've suggested various enhancements or security fixes.

## Directives

- SQLAuthenticate
- SQLAuthTypes
- SQLBackend
- SQLConnectInfo
- SQLDefaultGID
- SQLDefaultHomedir
- SQLDefaultUID
- SQLEngine
- SQLGroupInfo
- SQLGroupWhereClause
- SQLHomedirOnDemand
- SQLLog
- SQLLogFile
- SQLMinID
- SQLMinUserGID
- SQLMinUserUID
- SQLNamedQuery
- SQLNegativeCache
- SQLRatios
- SQLRatioStats
- SQLShowInfo
- SQLUserInfo
- SQLUserWhereClause

The following directives have been deprecated, and are no longer documented or supported:

- MySQLInfo (replaced with SQLConnectInfo)
- PostgresInfo (replaced with SQLConnectInfo)
- PostgresPort (replaced with SQLConnectInfo)
- SQLAuthoritative (replaced with SQLAuthenticate)
- SQLDoAuth (replaced with SQLAuthenticate)
- SQLDoGroupAuth (replaced with SQLAuthenticate)
- SQLEmptyPasswords (replaced with SQLAuthTypes)
- SQLEncryptedPasswords (replaced with SQLAuthTypes)
- SQLGidField (replaced with SQLUserInfo)
- SQLGroupGIDField (replaced with SQLGroupInfo)
- SQLGroupnameField (replaced with SQLGroupInfo)
- SQLGroupMembersField (replaced with SQLGroupInfo)
- SQLGroupTable (replaced with SQLGroupInfo)
- SQLHomedir (replaced with SQLDefaultHomedir)
- SQLHomedirField (replaced with SQLUserInfo)
- SQLKey (replaced with SQLUserWhereClause)
- SQLKeyField (replaced with SQLUserWhereClause)
- SQLLogDirs (replaced with SQLLog)
- SQLLogHits (replaced with SQLLog)
- SQLLogHosts (replaced with SQLLog)
- SQLLoginCountField (replaced with SQLLog)
- SQLLogStats (replaced with SQLLog)
- SQLPasswordField (replaced with SQLUserInfo)
- SQLPlaintextPasswords (replaced with SQLAuthTypes)
- SQLProcessGrEnt (replaced with SQLAuthenticate)
- SQLProcessPwEnt (replaced with SQLAuthenticate)
- SQLSSLHashedPasswords (replaced with SQLAuthTypes)
- SQLScrambledPasswords (replaced with SQLAuthTypes)
- SQLShellField (replaced with SQLUserInfo)
- SQLUidField (replaced with SQLUserInfo)
- SQLUsernameTable (replaced with SQLUserInfo)
- SQLUserTable (replaced with SQLUserInfo)
- SQLWhereClause (replaced with SQLUserWhereClause)

## SQLAuthenticate

Syntax: SQLAuthenticate on|off or
Syntax: SQLAuthenticate [users] [groups] [userset[fast]] [groupset[fast]]
Default: on
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.5rc1 and later

The `SQLAuthenticate` directive configures `mod_sql`'s authentication behavior, controlling whether to provide user and/or group information during authentication, and how that provisioning is performed. The parameters may appear in any order.

The available parameter values are:

- on
  Shorthand for `SQLAuthenticate users groups userset groupset`.
- off
  Disables all `mod_sql` authentication functions.
- users
  If present, `mod_sql` will do user lookups. If not present, `mod_sql` will do no user lookups at all, including the `{set|get|end}pwent()` calls (see below).
- groups
  If present, `mod_sql` will do group lookups. If not present, `mod_sql` will do no group lookups at all, including the `{set|get|end}grent()` calls (see below).
- userset[fast]
  If present, `mod_sql` will process the potentially expensive `{set|get|end}pwent()` calls. If not present, `mod_sql` will not process these calls. Adding the suffix "fast" tells `mod_sql` to process the users as a single large query, rather than making a query per user. This may significantly reduce the number of queries against the database at the expense of increased memory use. This parameter will have no effect if "users" is not specified.
- groupset[fast]
  If present, `mod_sql` will process the potentially expensive `{set|get|end}grent()` calls. If not present, `mod_sql` will not process these calls. Adding the suffix "fast" tells `mod_sql` to process the groups as a single large query, rather than making a query per group. This may significantly reduce the number of queries against the database at the expense of increased memory use. This parameter will have no effect if "groups" is not specified.

The `SQLLog` and `SQLShowInfo` directives will always be processed by `mod_sql`. The `SQLAuthenticate` directive only affects the user and group lookup/authentication portions of the module.

Turning off (i.e. by not including) the userset or groupset parameters affects the functionality of `mod_sql`. Not allowing these lookups may remove the ability to control access or control functionality by group membership, depending on your other authentication handlers and the data available to them. At the same time, choosing not to do these lookups may dramatically speed login for many large sites.

The "fast" suffix is not appropriate for every site. Normally, `mod_sql` will retrieve a list of users and groups, and get information from the database on a per-user or per-group basis. This is query intensive: it requires (nn + 1) queries, where n is the number of users or groups to lookup. By choosing "fast" lookups, `mod_sql` will make a single `SELECT` query to get information from the database.

In exchange for the radical reduction in the number of queries, the single query will increase the memory consumption of the process; all group or user information will be read at once rather than in discrete chunks.

Group Table Structure
Normally mod_sql allows multiple group members per row, and multiple rows per group. If you use the "fast" option for groupset, you must use only one row per group. For example, normally `mod_sql` treats the following three tables in exactly the same way:

    |--------------------------------------------------|
    |  GROUPNAME  |  GID  |  MEMBERS                   |
    |--------------------------------------------------|
    | group1      | 1000  | naomi                      |
    | group1      | 1000  | priscilla                  |
    | group1      | 1000  | gertrude                   |
    |--------------------------------------------------|

    |--------------------------------------------------|
    |  GROUPNAME  |  GID  |  MEMBERS                   |
    |--------------------------------------------------|
    | group1      | 1000  | naomi, priscilla           |
    | group1      | 1000  | gertrude                   |
    |--------------------------------------------------|

    |--------------------------------------------------|
    |  GROUPNAME  |  GID  |  MEMBERS                   |
    |--------------------------------------------------|
    | group1      | 1000  | naomi, priscilla, gertrude |
    |--------------------------------------------------|

If you use the "fast" option, `mod_sql` assumes that all entries are structured like the last example.

## SQLAuthTypes

Syntax: SQLAuthTypes ["Backend" | "Crypt" | "Empty" | "OpenSSL" | "Plaintext"] ...
Default: None
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.0 and later

The `SQLAuthTypes` directive specifies which authentication method are to be allowed, and their order of use. You must specify at least one authentication method.

The current supported authentication methods are:

- Backend
  Allows database-specific backend passwords. Not all backend databases support this option. For example, MySQL datatabases use this option to authenticate MySQL `'PASSWORD()'` encrypted passwords. The Postgres backend, however, does nothing. Caveat: if your MySQL activity log is world-readable, the user password will be visible. You have been warned.
- Crypt
  Allows passwords in the database to be of Unix `crypt(3)` form.
- Empty
  Allows empty passwords in the database, which match against any password the user may give. The database field must be a truly empty string; `NULL` values are not acceptable as empty passwords. Be very careful if using this authentication method.
- OpenSSL
  Allows passwords in the database to be of the form `'{digest-name}hashed-value'`, where `hashed-value` is the base64-encoded digest of the passsword. Only available if you define `HAVE_OPENSSL` when you compile `proftpd` and you link with OpenSSL's `libcrypto` library.
- Plaintext
  Allows passwords in the database to be in plaintext.

For example:

      SQLAuthTypes Crypt Empty

configures `mod_sql` to first attempt to verify the password using the Unix `crypt(3)` function, then, if that fails, determine if the password in the database is empty (thus matching any given password). If all of the configured authentication methods fail, `mod_sql` will fail to authenticate the user.

Note: this directive deprecates the following configuration directives:

- `SQLEmptyPasswords`
- `SQLEncryptedPasswords`
- `SQLPlaintextPasswords`
- `SQLScrambledPasswords`
- `SQLSSLHashedPasswords`

## SQLBackend

Syntax: SQLBackend backend
Default: Depends
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.3.0rc1 and later

In 1.3.0rc1, the `mod_sql` module gained the ability to be compiled with multiple backend modules supported, e.g. to have both `mod_sql_mysql` and `mod_sql_postgres` usable in the same `proftpd` daemon. The `SQLBackend` directive configures which of these different database backends should be used.

If there is only one backend module compiled in, the `SQLBackend` directive is not needed. If there are multiple backend modules compiled and no `SQLBackend` directive is specified, then `mod_sql` will default to using the first backend module listed. For instance, if you configured `proftpd` using a `configure` command such as:

      ./configure --with-modules=mod_sql:mod_sql_postgres:mod_sql_mysql ...

then `mod_sql` would default to using `mod_sql_postgres` as the backend module to use.

You might have multiple `<VirtualHost>` sections which use different SQL backends, e.g.:

      <VirtualHost 1.2.3.4>
        SQLBackend mysql
        ...
      </VirtualHost>

      <VirtualHost 5.6.7.8>
        SQLBackend postgres
        ...
      </VirtualHost>

Use "mysql" for the `mod_sql_mysql` module, and "postgres" for the `mod_sql_postgres` module.

## SQLConnectInfo

Syntax: SQLConnectInfo connection-info [username] [password] [policy]
Default: None
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.0 and later

The `SQLConnectInfo` directive configures the information necessary to connect to the backend database. The connection-info parameter specifies the database, host, port, and other backend-specific information. The optional username and password parameters specify a username and password to use when connecting to the database. Both default to `NULL`, which the backend will treat in some backend-specific manner. If you specify a password, you must specify a username. If no `SQLConnectInfo` directive is specified, `mod_sql` will disable itself.

Any given database backend has the opportunity, though not necessarily the responsibility, to check for syntax errors in the connection-info field at server startup, but you should not expect semantic errors (i.e., cannot connect to the database) to be caught until `mod_sql` attempts to connect for a given host.

A given database connection is governed by a connection policy that specifies when a connection should be opened and when it should be closed. There are three options:

- PERSESSION
  Open a database connection at the start of the session and close the database connection at the end of the session.
- number (TIMED)
  Timed database connections that close themselves after number seconds of inactivity.

If a connection policy is not specified, if the policy is not a number or is a number less than 1, or if the policy is the string "PERSESSION", the `PERSESSION` policy will be used.

If the connection policy is any number greater than 0, it specifies the number of seconds that a connection will be held open without activity. After that many seconds of database inactivity, the connection to the database will be closed. As soon as database activity starts again, the connection will be opened and the timer will restart.

The MySQL and Postgres backends' connection-info is expected to be of the form:

      database[@hostname][:port]

hostname will default to a backend-specific hostname (which happens to be 'localhost' for both the MySQL and Postgres backends), and port will default to a backend-specific default port (3306 for the MySQL backend, 5432 for the Postgres backend).

From the MySQL documentation:

> the value of host may be either a hostname or an IP address. If host is NULL or the string "localhost", a connection to the local host is assumed. If the OS supports sockets (Unix) or named pipes (Windows), they are used instead of TCP/IP to connect to the server.

From the PostgreSQL documentation:

> If [the hostname] begins with a slash, it specifies Unix-domain communication rather than TCP/IP communication; the value is the name of the directory in which the socket file is stored. The default is to connect to a Unix-domain socket in `/tmp`.

If you plan to use the `TIMED` connection policy, consider the effect of directives such as `DefaultRoot` on local socket communication: once a user has been `chroot()`ed, the local socket file will probably not be available within the `chroot` directory tree, and attempts to reopen communication will fail. One way around this may be to use hardlinks within the user's directory tree. `PERSESSION` connections are not affected by this because the database will be opened prior to the `chroot()` call, and held open for the life of the session. Network communications are not affected by this problem. For example, while `localhost` would not work for MySQL since the MySQL client library will try to use socket communications for that host, `127.0.0.1` will work (as long as your database is setup to accept these connections).

Examples:

      # Connect to the database 'ftpusers' via the default port at host
      # 'foo.com'.  Use a NULL username and NULL password when connecting.
      # A connection policy of PERSESSION is used.
      SQLConnectInfo ftpusers@foo.com

      # Connect to the database 'ftpusers' via port 3000 at host 'localhost'.
      # Use the username 'admin' and a NULL password when connecting.
      # A connection policy of PERSESSION is used.
      SQLConnectInfo ftpusers:3000 admin

      # Connect to the database 'ftpusers' via port 3000 at host 'foo.com'.
      # Use the username 'admin' and password 'mypassword' when connecting.
      # A connection policy of PERSESSION is used.
      SQLConnectInfo ftpusers@foo.com:3000 admin mypassword

      # Connect to the database 'ftpusers' via port 3000 at host 'foo.com'.
      # Use a username of 'admin' and a password of 'mypassword' when
      # connecting.  A 30 second timer of connection inactivity is activated.
      SQLConnectInfo ftpusers@foo.com:3000 admin mypassword 30

Backends may require different information in the connection-info field; check your backend module for more detailed information.

Note: this directive deprecates the following configuration directives:

- `MySQLInfo`
- `PostgresInfo`
- `PostgresPort`

## SQLDefaultGID

Syntax: SQLDefaultGID default-gid
Default: 65533
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.0 and later

The `SQLDefaultGID` directive configures the default GID for users. This value must be greater than any configured `SQLMinUserGID`.

See also: `SQLMinUserGID`

## SQLDefaultHomedir

Syntax: SQLDefaultHomedir path
Default: None
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.5rc1 and later

The `SQLDefaultHomedir` directive configures a default home directory for all users authenticated with this module, overriding any (deprecated) `SQLHomedirField` directive. If no home directory is set with either directive, authentication fails. This directive does not change the data retrieved from the database: if you specify a home directory field to `SQLUserInfo`, that field's data will be returned as the user's home directory, whether that data is a legal directory, or an empty string, or `NULL`.

See also: SQLUserInfo

## SQLDefaultUID

Syntax: SQLDefaultUID default-uid
Default: 65533
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.0 and later

The `SQLDefaultUID` directive configures the default UID for users. This value must be greater than any configured `SQLMinUserUID`.

See also: `SQLMinUserUID`

## SQLEngine

Syntax: SQLEngine on|off|auth|log
Default: SQLEngine on
Context: server config, `<VirtualHost>`, `<Global>`, `<Anonymous>`
Module: mod_sql
Compatibility: 1.3.0rc1 and later

The `SQLEngine` directive is used to specify how `mod_sql` will operate. By default, `SQLEngine` is on, and `mod_sql` will operate as normal. Setting `SQLEngine` to off will effectively disable the module.

In addition to on and off, `SQLEngine` accepts two other values: auth and log. If you wish to use `mod_sql` for authentication and not for logging (via `SQLLog`), use auth. Conversely, to do only `SQLLog`-type logging, and no authentication, use log.

This directive can be used to have `<Anonymous>` sections that do not use `mod_sql`, e.g.:

      <Anonymous ~ftp>
        ...
        SQLEngine off
        ...
      </Anonymous>

## SQLGroupInfo

Syntax: SQLGroupInfo group-table group-name gid members
Default: "groups groupname gid members"
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.5rc1 and later

The `SQLGroupInfo` directive configures the group table and fields that hold group information. The parameters for this directive are described below:

- grouptable
  Specifies the name of the table that holds group information.
- groupname
  Specifies the field in the group table that holds the group name.
- gid
  Specifies the field in the group table that holds the group's GID.
- members
  Specifies the field in the group table that holds the group members.

If you need to change any of these field names from the default, you need to specify all of them.

## SQLGroupWhereClause

Syntax: SQLGroupWhereClause where-clause
Default: off
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.5rc1 and later

The directive is used to configure a WHERE clause that is added to every group query. The WHERE clause must contain all relevant punctuation, and must not contain a leading "and".

As an example of a possible use for this directive, imagine if your group table included a "LoginAllowed" field:

      SQLGroupWhereClause "LoginAllowed = 'true'"

would be appended to every group-related query as the string:

      " WHERE (LoginAllowed = 'true')"

## SQLHomedirOnDemand

Syntax: SQLHomedirOnDemand on|off
Default: off
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.0 and later

The `SQLHomedirOnDemand` directive configures `mod_sql` to automatically create a user's home directory if that directory does not exist during the login process.

## SQLLog

Syntax: SQLLog cmd-set query-name ["IGNORE_ERRORS"]
Default: None
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.1 and later

This directive is used to log information to a database table. Multiple `SQLLog` directives can be in effect for any command; for example, a user changing directories can trigger multiple logging statements.

The first parameter to `SQLLog`, the cmd-set, is a comma-separated (no spaces) list of FTP commands for which this log command will trigger. The list of commands is too long to list in entirety; commands include `CWD, DELE, HELP, LIST, MKD, MODE, NLST, PASS, PASV, PORT` and many more. For the complete list check the FTP RFCs. Normally `mod_sql` will log events after they have completed successfully; in the case of the `QUIT` command, `mod_sql` logs prior to the server's processing of the command. (Note, however, that the client may not issue a `QUIT` before logging out; in this case, use a command of `EXIT` rather than `QUIT`. `EXIT` is not a real FTP command, but it is used here to provide a means for having `SQLLog` work whenever a session ends.)

FTP commands in the command set will only be logged if they complete successfully. Prefixing any command with "ERR_" will cause logging to occur only if there was an error in the command's processing. To log both errors and successful completion of a given command X, therefore, you'll need both "X" and "ERR_X" in your cmd-set.

The special command "*" matches all FTP commands, while "ERR_*" matches all errors.

The second parameter is the name of a query defined by a `SQLNamedQuery` directive. The query must be an `UPDATE`, `INSERT`, or `FREEFORM` type query; explicit `SELECT` queries will not be processed.

The third parameter is optional. If you add "IGNORE_ERRORS" as the third parameter, `SQLLog` will not check for errors in the processing of the named query. Any value for this parameter other than the string "IGNORE_ERRORS" (case-insensitive) will not cause errors to be ignored.

Normally, `SQLLog` directives are considered important enough that errors in their processing will cause `mod_sql` to abort the client session. References to non-existent named queries will not abort the client session, but may result in database corruption (in the sense that the expected database `UPDATE` or `INSERT` will not occur). Check your directives carefully.

Examples:

      SQLLog PASS updatecount
      SQLNamedQuery updatecount UPDATE "count=count+1 WHERE userid='%u'" users

together, these replicate the deprecated "`SQLLoginCountField` count" directive; if the current user was "joe", this would translate into the query "UPDATE users SET count=count+1 WHERE userid='joe'". This query would run whenever a user was first authenticated.

      SQLLog CWD updatedir
      SQLNamedQuery updatedir UPDATE "cwd='%d' where userid='%u'" users

together these replicate the logging side of the deprecated "`SQLLogDirs` cwd" directive; if the current user was "joe" and the current working directory were `/tmp`, this would translate into the query "UPDATE users SET cwd='/tmp' WHERE userid='joe'". This query would run whenever a user changed directories.

      SQLLog RETR,STOR insertfileinfo
      SQLNamedQuery insertfileinfo INSERT "'%f', %b, '%u@%v', now()" filehistory

would log the name of any file stored or retrieved, the number of bytes transferred, the user and host doing the transfer, and the time of transfer (at least in MySQL). This would translate into a query like: "INSERT INTO filehistory VALUES ('somefile', 12345, 'joe@joe.org', '21-05-2001 20:01:00')"

## SQLLogFile

Syntax: SQLLogFile file
Default: None
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.8rc2 and later

The `SQLLogFile` directive is used to a specify a log file for `mod_sql` reporting and debugging, and can be done a per-server basis. The file parameter must be the full path to the file to use for logging. Note that this path must not be to a world-writeable directory and, unless `AllowLogSymlinks` is explicitly set to on (generally a bad idea), the path must not be a symbolic link.

If file is "none", no logging will be done at all; this setting can be used to override a `SQLLogFile` setting inherited from a `<Global>` context.

## SQLMinID

Syntax: SQLMinID minimum-id
Default: 999
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.0 and later

`SQLMinID` is a quick way of setting both `SQLMinUserGID` and `SQLMinUserUID`. These values are checked whenever retrieving a user's GID or UID.

See also: `SQLMinUserGID`, `SQLMinUserUID`

## SQLMinUserGID

Syntax: SQLMinUserGID minimum-gid
Default: 999
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.0 and later

`SQLMinUserGID` is checked whenever retrieving a user's GID. If the retrieved value for GID is less than the value of `SQLMinUserGID`, it is reported as the value of `SQLDefaultGID`.

## SQLMinUserUID

Syntax: SQLMinUserUID minimum-uid
Default: 999
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.0 and later

`SQLMinUserUID` is checked whenever retrieving a user's UID. If the retrieved value for UID is less than the value of `SQLMinUserUID`, it is reported as the value of `SQLDefaultUID`.

## SQLNamedQuery

Syntax: SQLNamedQuery name type query-string [table]
Default: None
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.4 and later

SQLNamedQuery specifies a query and an identifier (name) for later use by `SQLShowInfo` and `SQLLog`.

It is strongly recommended that you read documentation on the `LogFormat` and `ExtendedLog` directives, as the meta-sequences available to `SQLNamedQuery` are largely equivalent.

The first parameter, name, should be unique across all named queries and must not contain spaces. The result of re-using a name is undefined.

The second parameter, type, is the type of query, either "SELECT", "UPDATE", "INSERT", or "FREEFORM". See the note below for information on FREEFORM type queries.

The third parameter is the substance of the database query itself; this should match the form of the second parameter. The meta-sequences accepted are exactly equivalent to the `LogFormat` directive except the following are not accepted:

- `%{FOOBAR}e`
  For `LogFormat`, this logs the content of environment variable "FOOBAR". This is not bavailable in `mod_sql`.
- `%{format}t` and `%t`
  These two meta-sequences logged the local server time; they are not available in `mod_sql`. Your database undoubtedly provides another way to get the time; for example, MySQL provides the `now()` function.

and the following is in addition to the `LogFormat` meta-sequences:

- `%d`
  The current working directory or "-" if none.
- `%{n}`
  This meta-sequence is used internally by `mod_sql` and other third-party modules and patches to pass information to the database. Using this meta-sequence in anything other than an `INSERT` or `UPDATE` query is an error, and using this meta-sequence unless directed to by a third-party module or patch is also an error.

The correct form of a query will be built from the directive arguments, except in the case of `FREEFORM` queries which will be sent directly to the database. The examples below show the way queries are built from the arguments.

The fourth parameter, table, is only necessary for `UPDATE` or `INSERT` type queries, but is required for those types.

Note: `FREEFORM` queries are a necessary evil; the simplistic query semantics of the `UPDATE`, `INSERT`, and `SELECT` type queries do not sufficiently expose the capabilities of most backend databases. At the same time, using a `FREEFORM` query makes it impossible for `mod_sql` to check whether the query type is appropriate, making sure that a `SELECT` query is not used in a `SQLLog` directive, for instance. Wherever possible, it is recommended that a specific query type be used.

Examples:

      SQLNamedQuery count SELECT "count from users where userid='%u'"

creates a query named "count" which could be used by `SQLShowInfo` to inform a user of their login count. The actual query would look something like "SELECT count FROM users WHERE userid='matilda'" for user "matilda".

      SQLNamedQuery updatecount UPDATE "count=count+1 WHERE userid='%u'" users

creates a query named "updatecount" which could be used by `SQLLog` to update a user login counter in the table `users`. The actual query would look something like "UPDATE users SET count=count+1 WHERE userid='persephone'" for user "persephone".

      SQLNamedQuery accesslog INSERT "now(), '%u'" accesslog

creates a query named "accesslog" which could be used by `SQLLog` to track access times by clients. The actual query would look something like "INSERT INTO accesslog VALUES (now(), 'pandora')" for user "pandora". Note that this may be too simplistic for your table structure, since most databases require data for all columns to be provided in an `INSERT` statement of this form. See the following `FREEFORM` query for an example of something which may suit your needs better.

      SQLNamedQuery accesslog FREEFORM "INSERT INTO accesslog(date, user) VALUES (now(), '%u')"

creates a query named "accesslog" which could be used by `SQLLog` to track access times by clients. The actual query would look something like "INSERT INTO accesslog(date, user) VALUES (now(), 'tilda')" for user "tilda".

## SQLNegativeCache

Syntax: SQLNegativeCache on|off
Default: off
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.7rc1 and later

`SQLNegativeCache` specifies whether or not to cache negative responses from SQL lookups when using SQL for UID/GID lookups. Depending on your SQL tables, there can be a significant delay when a directory listing is performed as the UIDs not in the SQL database are repeatedly looked up in an attempt to present usernames instead of UIDs in directory listings. With `SQLNegativeCache` set to on, negative ("not found") responses from SQL queries will be cached and speed will improve on directory listings that contain many users not present in the SQL database.

## SQLRatios

Syntax:
Default: None
Context:
Module: mod_sql
Compatibility:

## SQLRatioStats

Syntax:
Default: None
Context:
Module: mod_sql
Compatibility:

## SQLShowInfo

Syntax: SQLShowInfo cmd-set numeric query-string
Default: None
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.5rc1 and later

This directive creates a message to be sent to the user after any successful command.

The first parameter, the cmd-set, is a comma separated (no spaces) list of FTP commands for which this log command will trigger. The list of commands is too long to list in entirety; commands include: `CWD, DELE, HELP, LIST, MKD, MODE, NLST, PASS, PASV, PORT` and many more. For the complete list check the FTP RFCs.

FTP commands in the command set will only be triggered if they complete successfully. Prefixing any command with "ERR_" will show information only if there was an error in command processing. To send a message on both errors and successfull completion of a given command X, therefore, you'll need both "X" and "ERR_X" in your cmd-set.

The special command "*" matches all FTP commands, while "ERR_*" matches all errors.

The second parameter, numeric, specifies the numeric value of the message returned to the FTP client. Do not choose a number blindly: message numbers may be parsed by clients. In most cases you will want to use `214`, the "Help message" numeric. It specifies that the information is only meant to be human readable.

The third parameter, query-string, is exactly equivalent to the query-string parameter to the `SQLLog` directive, with one addition:

- `%{name}`
  The first return value from the `SQLNamedQuery` identified by "name". There is currently no way to retrieve more than one value from the database at a time.

Any references to non-existent named queries, non-`SELECT` or -`FREEFORM` type queries, or references to queries which return a NULL first value, will be replaced with the string "{null}". For example:

      SQLNamedQuery count SELECT "count from users where userid='%u'"
      SQLShowInfo PASS "230" "You've logged on %{count} times, %u"

As long as the information is in the database, these two directives specify that the user will be greeted with their login count each time they successfully login. Note the use of the "230" numeric, which means "User logged in, proceed". "230" is appropriate in this case because the message will be sent immediately after their password has been accepted and the session has started.

## SQLUserInfo

Syntax: SQLUserInfo user-table user-name passwd uid gid home-dir shell
Default: "users userid passwd uid gid homedir shell"
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.5rc1 and later

The `SQLUserInfo` directive configures the user table and fields that hold user information. If you need to change any of these field names from the default, you must specify all of them, whether NULL or not. The parameters are described below:

- usertable
  Specifies the name of the table that holds user information.
- username
  Specifies the field in the user table that holds the username.
- passwd
  Specifies the field in the user table that holds the user's password.
- uid
  Specifies the field in the user table that holds the user's UID. When a UID is retrieved from the database it is checked against the value of `SQLMinUserUID`. If the field name is specified as "NULL" the database will not be queried for this value and the user's UID will be set to the value of `SQLDefaultUID`.
- gid
  Specifies the field in the user table that holds the user's GID. When a GID is retrieved from the database it is checked against the value of `SQLMinUserGID`. If the field name is specified as "NULL" the database will not be queried for this value and the user's GID will be set to the value of `SQLDefaultGID`.
- homedir
  Specifies the field in the user table that holds the user's home directory. If the fieldname is specified as "NULL" the database will not be queried for this value and the user's home directory will be set to the value of `SQLDefaultHomedir`. If no home directory is set with either directive, user authentication will be automatically turned off.
- shell
  Specifies the field in the user table that holds the user's shell. If the fieldname is specified as "NULL" the database will not be queried and the shell will be reported as an empty string ("").

As of `1.2.9rc1`, the `SQLUserInfo` directive accepts an alternate syntax:

      SQLUserInfo custom:/name

where name refers to a configured SELECT `SQLNamedQuery`. This named query must return one row, and return the following columns, in this order: `username, passwd, uid, gid, homedir, shell`. The configured query may make use of the variables mentioned in the `SQLLog` description. This syntax allows the administrator a flexible way of constructing queries as needed. Note that if you want use the given `USER` name, you should use the `%U` variable, not `%u`; the latter requires the locally authenticated user name, which is exactly what `SQLUserInfo` is meant to provide.

See Also: `SQLLog`, `SQLNamedQuery`

## SQLUserWhereClause

Syntax: SQLUserWhereClause where-clause
Default: None
Context: server config, `<VirtualHost>`, `<Global>`
Module: mod_sql
Compatibility: 1.2.5rc1 and later

The directive is used to configure a WHERE clause that is added to every user query. The WHERE clause must contain all relevant punctuation, and must not contain a leading "and".

As an example of a possible use for this directive, imagine if your user table included a "LoginAllowed" field:

      SQLUserWhereClause "LoginAllowed = 'true'"

would be appended to every user-related query as the string:

      " WHERE (LoginAllowed = 'true')"

## Installation

The `mod_sql` module is distributed with ProFTPD. Simply follow the normal steps for using third-party modules in proftpd:

      ./configure --with-modules=sql-module-opts

where the specific sql-module-opts depend on your database needs. For example, if using MySQL, sql-module-opts would be "mod_sql:mod_sql_mysql". `mod_sql` is the main SQL-processing engine, and `mod_sql_mysql` is the backend sub-module that handles MySQL-specific details. If Postgres is your database of choice, sql-module-opts would be "mod_sql:mod_sql_postgres".

You will also need to tell `configure` how to find the database-specific libraries and header files:

      ./configure --with-modules=sql-module-opts \
        --with-includes=/path/to/db/header/file/dir \
        --with-libraries=/path/to/db/library/file/dir

Complete the build with the following standard commands:

      make
      make install

Author: $Author: castaglia $
Last Updated: $Date: 2006/03/09 18:50:34 $

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