FreeTDS User Guide: A Guide to Installing, Configuring, and Running FreeTDS
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# The `freetds.conf` file

## What it does

FreeTDS uses a configuration file `freetds.conf` (the name can be controlled by an environment variable). Its format is similar to Samba's modified "`win.ini`" format. Its foremost job is to relate dataserver names, as known to your programs [1] , to machine names, as known your network. That is, while your machines have names known to the network, the dataservers on your machines have names known only to your FreeTDS client programs. The configuration file can then further describe that dataserver in greater detail, as need be.

| FreeTDS also supports an older configuration file format, known as the `interfaces` file. Use `freetds.conf` unless `interfaces` is needed for your situation. It is easier to read, and it is where all the new options are being added. FreeTDS looks for `freetds.conf` first, falling back on `interfaces` only if `freetds.conf` is not found. Should you need it, more information about `interfaces` can be found in the Appendix.

## Where it goes

The default location of `freetds.conf` is determined by the `--sysconfdir` option of configure. If you don't specify anything, configure's default `sysconfdir` is `/usr/local/etc`.

In addition, FreeTDS will look for a file `.freetds.conf` in the user's home directory (`~/.freetds.conf`).

The actual name and location of `freetds.conf` may be specified by the environment variable `FREETDS` (or `FREETDSCONF`, same effect). See Environment Variables, below.

FreeTDS reads the user's `${HOME}/``.freetds.conf` before resorting to the system-wide `sysconfdir/``freetds.conf`. The first properly configured (i.e., a readable file with a section for the server) `freetds.conf` file will be the one used.

## What it looks like

The `freetds.conf` file is composed of two types of sections: a `[global]` section, and one `[`dataserver`]` section for each dataserver. Settings in the `[global]` section affect all dataservers, but can be overridden in a `[`dataserver`]` section. For example

Example 3-1. A `freetds.conf` file example

    [global]
    	tds version = 4.2

    [myserver]
    	host = ntbox.mydomain.com
    	port = 1433

    [myserver2]
    	host = unixbox.mydomain.com
    	port = 4000
    	tds version = 5.0

    [myserver3]
    	host = instancebox.mydomain.com
    	instance = foo
    	tds version = 8.0

In this example, the default TDS version for all dataservers is set to `4.2`. It is then overridden for `myserver2` (a Sybase server) which uses `5.0`, and `myserver3` (a MSSQL 2000 server) which uses `8.0`.

Note that `myserver3` uses a named instance configuration, instead of a port number.

Usually, it is sufficient to state the only server's hostname and TDS protocol. Everything else can be inferred, unless your setup (or your server's) strays from the defaults.

| Some people seem to feel safer using the IP address for the server, rather than its name. We don't recommend you do that. Use the name, and benefit from the inherent advantages. That's why DNS was invented in the first place, you know.

It bears mentioning here that prior versions of FreeTDS were quite fussy about domain logins, forcing users to make explicit per-server entries in `freetds.conf`. That is no longer the case. If the username has the form `DOMAIN\username`, FreeTDS will automatically use a domain login.

Table 3-2. `freetds.conf` settings

Name | Possible Values | Default | Meaning
--- | --- | --- | ---
tds version | `--with-tdsver` value (`5.0` if unspecified) Overridden by TDSVER. | The TDS protocol version to use when connecting. | 4.2, 5.0, 7.0, 8.0
host | host name or IP address | none | The host that the dataserver is running on.
port | any valid port |
Product | Version | Default Port
Sybase SQL Server | prior to System 10 | 1433
Sybase SQL Server | 10 and up | 5000
Sybase SQL Anywhere | 7 | 2638
Microsoft SQL Server | all | 1433
| The port number that the dataserver is listening to. Please note: The "defaults" to the left are the server's default settings. FreeTDS chooses its default port based on the TDS protocol version: `5000` for TDS `5.0`, and `1433` for everything else. Overridden by TDSPORT.
initial block size | multiple of 512 | 512 | Specifies the maximum size of a protocol block. Don't mess with unless you know what you are doing.
dump file | any valid file name | none Overridden by TDSDUMP. | Specifies the location of a tds dump file and turns on logging
dump file append | yes/no | no | Appends dump file instead of overwriting it. Useful for debugging when many processes are active.
timeout | 0- | none | Sets period to wait for response of query before timing out.
connect timeout | 0- | none | Sets period to wait for response from connect before timing out.
emulate little endian | yes/no | no | Forces big endian machines (Sparc, PPC, PARISC) to act as little endian to communicate with MS Servers. Set automatically for TDS 7.0/8.0 on big endian hosts
client charset | any valid iconv character set | ISO-8859-1[a] | Makes FreeTDS use iconv to convert to and from the specified character set from UCS-2 in TDS 7.0/8.0. As of 0.62 FreeTDS uses iconv to convert all character data, so there's no need to match the server's charset to insert any characters the server supports.
text size | 0 to 4,294,967,295 | 4,294,967,295 | default value of TEXTSIZE, in bytes. For text and image datatypes, sets the maximum width of any returned column. Cf. set TEXTSIZE in the T-SQL documentation for your server.
instance | instance name | none | Name of Microsoft SQL Server instance to connect to. The port will be detected automatically.
debug flags | Any number even in hex or octal notation | 0x4fff | Sets granularity of logging. A bitmask. See table below for specification.
encryption | off/request/required | off | Specify if encryption is desidered. Supported for Microsoft servers. `off` disables encryption (only if needed); `request` means use if available; `required` means create and allow encrypted connections only.
Notes: a. Valid for ISO 8859-1 character set. See Localization and TDS 7.0 for more information.

### Overrides

Many settings in `freetds.conf` can be overridden by environment variables.

Also dataserver can be decorated adding informations for port or instance name using port override syntax.

### Controlling log details

> The logging capability has helped solve innumerable cases, some trivial and some very low-level bugs. Sometimes a developer needs very detailed information about one function, whereas someone else may interested only in whether or not a particular function is called, or even want to see only the SQL that was transmitted to the server.

The log's granularity can be controlled with the `debug flags` entry. The default value (`4FFF` hex) gives a level of detail that is useful for resolving problems via the mailing list.

Table 3-3. Valid bitmask values for `debug flags` entry in `freetds.conf`

Value | Meaning
--- | ---
0x80 | function trace and info
0x40 | information level 2
0x20 | information level 1
0x10 | network
0x08 | warning
0x04 | error
0x02 | severe error
0x1000 | show pid
0x2000 | show time
0x4000 | show source level info (source file and line)
0x8000 | thread id (not implemented)

For more about the wonderful world of FreeTDS logs, see Logging.

### Deprecated options

As of version 0.62 the following options are deprecated and supported only for backward compatibility.

Deprecated `freetds.conf` settings

- `try server login`

- `try domain login`

- `nt domain`

- `cross domain login`

- `debug level`

### Notes

[1] | In general, the dataserver name is arbitrary and local; it's used only by your client programs to tell FreeTDS which server to connect to. You can choose any name you like. Sybase SQL Anywhere (a/k/a Sybase ASA), however, is fussy. You must use the database's name as your dataserver name. Otherwise, the server will refuse your connection.

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