First, install the following libraries:

    $ brew install unixodbc
    $ brew install freetds --with-unixodbc

FreeTDS should already work now, without configuration:

    $ tsql -S [IP or hostname] -U [username] -P [password]
    locale is "en_US.UTF-8"
    locale charset is "UTF-8"
    using default charset "UTF-8"
    1> ^D

Onto unixODBC, we need to link to the driver, edit `/usr/local/etc/odbcinst.ini`:

    [FreeTDS]
    Description = TD Driver (MSSQL)
    Driver = /usr/local/lib/libtdsodbc.so
    Setup = /usr/local/lib/libtdsodbc.so
    FileUsage = 1

The test command we're using requires configuring a DSN, so edit `/usr/local/etc/odbc.ini`:

    [MYDSN]
    Driver = FreeTDS
    Server = [IP address]
    Port = 1433

The configuration for your DNS might vary, you might need the `TDS_Version` or `Servername` directives. The above worked for me for SQL Server 2008 R2. Now, run the test command:

    $ isql MYDSN [username] [password] -v
    +---------------------------------------+
    | Connected!                            |
    |                                       |
    | sql-statement                         |
    | help [tablename]                      |
    | quit                                  |
    |                                       |
    +---------------------------------------+
    SQL> ^D

If the test succeeded, you can continue onto installing the Python library `pyodbc`. Version 3.0.7 and before didn't link with unixODBC, so a change had to be made to `setup.py`, follow the steps at the bottom instead. The current version (3.0.10) has resolve this issue, so you can go ahead and install from pypi:

    pip install pyodbc

Now pyodbc should work:

    import pyodbc
    pyodbc.connect('DSN=MYDSN;UID=[username];PWD=[password]')

You don't need to have your DSN configured in `odbc.ini`, so clear that file. You probably want to select a database on connect, so change your connect line to read:

    pyodbc.connect('DRIVER=FreeTDS;SERVER=[IP address];PORT=1433;DATABASE=[database];UID=[username];PWD=[password]')

Note that you could also link to the library file of FreeTDS instead of using `odbcinst.ini`, like this:

    pyodbc.connect('DRIVER=/usr/local/lib/libtdsodbc.so;SERVER=[IP address];PORT=1433;DATABASE=[database];UID=[username];PWD=[password]')

## Reference -- Installing `pyodbc` version 3.0.7 and before

Version 3.0.7 didn't link with unixODBC on OS X, so a change had to be made to `setup.py`. Note that the current version of writing (3.0.10) doesn't have this issue. Follow these steps only to install the old version. Download the source package and extract it somewhere. Find the following lines (146-147):

        elif sys.platform == 'darwin':
            # OS/X now ships with iODBC.

And change this line:

            settings['libraries'].append('iodbc')

into:

            settings['libraries'].append('odbc')

Then run the following command to install:

    > python install .