Just as DNS defines hostnames for network addresses, freetds.conf uses a servername to define the properties of your server. [1]
In particular, FreeTDS needs to know:
Primary Server Properties
Hostname or IP address of the server
Port number or Instance name (not both)
TDS protocol version
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.
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. tsql -C reports the sysconfdir to let you confirm it.
In addition, FreeTDS will look for a file .freetds.conf in the user's home directory (${HOME}/.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 file used is the first one that is readable and contains a section for the server.
The following information is also provided in the freetds.conf manual page, cf. man freetds.conf.
The freetds.conf file format is similar to that of Samba's modified "win.ini". It
is composed of two types of sections: one [global] section, and a [servername] section for each servername. Settings in the [global] section affect all servernames, but can be overridden in a [servername] 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 = 7.1
In this example, the default TDS version for all servernames 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 7.1.
Usually, it is sufficient to state just the server's hostname and TDS protocol version. 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
4.2, 5.0, 7.0, 7.1, 7.2, auto
--with-tdsver value (5.0 if unspecified)
Overridden by TDSVER.
The TDS protocol version to use when connecting. "auto" tells FreeTDS to use an autodetection (trial-and-error) algorithm to choose the protocol version.
host
host name or IP address
none
The host that the servername 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 servername 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. Mutually exclusive with instance, below.
Overridden by TDSPORT.
instance
instance name
none
Name of Microsoft SQL Server instance to connect to. The port will be detected automatically. Mutually exclusive with port, above. Requires UDP connection to port 1434 on the server.
ASA database
valid database name
servername [section] name
Specifies the name of the default database when connecting to an ASA server. A TDS 5.0 login packet has a field called lservname. For most TDS servers, lservname is a user-defined string with no inherent meaning. ASA servers, however, requires that lservname contain a valid database name, and sets that as the default database for the connection. FreeTDS normally fills lservname with the [section] text.. This entry instead sets the database name independently of the [section] name.
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.
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 or above on big endian hosts
Makes FreeTDS use iconv to convert to and from the specified character set from UCS-2 in TDS 7.0 or above.
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.
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.
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.
In general, the servername 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. Unless you use the ASA Database property, you must use the database's name as your servername. Otherwise, the server will refuse your connection.
