Sql-server – “Unknown host machine name.” on FreeBSD + unixODBC + FreeTDS

I got some issues connecting to a Microsoft SQL Server 2012 from my FreeBSD 10.1 server.

I installed FreeTDS and unixODBC via ports. I compiled FreeTDS with unixODBC support. This ist my freetds.conf:

[server1]
  host = 192.168.100.147
  port = 1433
  tds version = 7.2

Invoking tsql works fine.

But when i try to connect via odbc with "osql" or "isql" the connection failes with the following error:

checking shared odbc libraries linked to isql for default directories...
    trying /tOH ... no
    trying /tOH ... no
    trying /tmp/sqlH ... no
    trying /tmp/sqlH ... no
    trying /usr/locH ... no
    trying /usr/locH ... no
    trying /tmp/sql.log ... no
    trying /home ... no
    trying /.odbc.ini ... no
    trying /usr/local/etc ... OK
checking odbc.ini files
    reading /root/.odbc.ini
[server1] not found in /root/.odbc.ini
    reading /usr/local/etc/odbc.ini
[server1] found in /usr/local/etc/odbc.ini
found this section:
    [server1]
      Driver = FreeTDS
      Servername = server1
looking for driver for DSN [server1] in /usr/local/etc/odbc.ini
  found driver line: "      Driver = FreeTDS"
  driver "FreeTDS" found for [server1] in odbc.ini
found driver named "FreeTDS"
"FreeTDS" is not an executable file
looking for entry named [FreeTDS] in /usr/local/etc/odbcinst.ini
  found driver line: "      Driver = /usr/local/lib/libtdsodbc.so"
  found driver /usr/local/lib/libtdsodbc.so for [FreeTDS] in odbcinst.ini
/usr/local/lib/libtdsodbc.so is an executable file
Using ODBC-Combined strategy
DSN [server1] has servername "server1" (from /usr/local/etc/odbc.ini)
cannot read "/root/.freetds.conf"
/usr/local/etc/freetds/freetds.conf is a readable file
looking for [server1] in /usr/local/etc/freetds/freetds.conf
found this section:
    [server1]
        host = 192.168.100.147
        port = 1433
        tds version = 7.2
looking up hostname for ip address 192.168.100.147

Configuration looks OK.  Connection details:

                   DSN:    server1
              odbc.ini:    /usr/local/etc/odbc.ini
                Driver:    /usr/local/lib/libtdsodbc.so
       Server hostname:    sqlsrv01
               Address:    192.168.100.147

Attempting connection as sa ...
+ isql server1 sa foobar -v
[S1000][unixODBC][FreeTDS][SQL Server]Unable to connect to data source
[01000][unixODBC][FreeTDS][SQL Server]Unknown host machine name.
[ISQL]ERROR: Could not SQLConnect

This is the content of my odbc.ini:

[server1]
  Driver = FreeTDS
  Servername = server1

And this is my odbcinst.ini:

[FreeTDS]
  Driver = /usr/local/lib/libtdsodbc.so
  Client Charset = UTF-8
  UsageCount = 1

I read severeal posts regarding to using the exact naming inf odbc.ini and freetds.conf, but the connection keeps failing.

Can anybody help?