[freetds] Unable to connect: Adaptive Server is unavailable or does not exist

Krish krishna.sunuwar at gmail.com
Tue May 7 00:45:48 EDT 2013

Thanks James

I think problem is port forwarding, ssh tunnel is not working from freeTDS.

The SQL Server is not in localhost, but it is in machine called
db_server. Access to db_server is restricted to mid_server. I created
tunnel with

$ssh -L 1433:db_server:1433 user at mid_server

The above port forwardign is working for Navicat. I can connect
localhost:1433 via Navicat and access all database in db_server. I
also can telnet localhost 1433. So main problem is freeTDS not working
port forwarding. Is there any way to get this work?

On Tue, May 7, 2013 at 6:26 AM, James K. Lowden <jklowden at freetds.org> wrote:
> On Mon, 06 May 2013 09:38:03 -0400
> Randy Syring <rsyring at gmail.com> wrote:
>> http://freetds.schemamania.org/userguide/logging.htm
>> to make sure you are connecting the way you think you are.  The error
>> is essentially saying it can't find the server.
> That's good advice.  Just to clarify, though, the careful reader can
> distinguish between "can't find the server" and "server didn't
> answer".
> If you try "man errno", you may find the OS error messages and their
> associated numbers are lists.  You saw,
>>      OS error 61, "Connection refused"
> $ man errno | sed -ne '/61 /,/^$/p'
>      61 ECONNREFUSED Connection refused.  No connection could be
> made because the target machine actively refused it.  This usually
> results from trying to connect to a service that is inactive on
> the foreign host.
> whereas a name lookup failure looks a little different:
> $ tsql -H no-such-host -p 17
> Error 20012 (severity 2):
>         Server name not found in configuration files.
> ...
> Error 20013 (severity 2):
>         Unknown host machine name.
> There was a problem connecting to the server
> (There should be an OS error for that, too, but the error-handling logic
> has no way to pass along the fact that the error status for
> gethostbyname(3) is in herror, not errno.)
> >From this we know you are reaching a machine ("locahost" was resolved,
> whew!) but that machine is not answering on the port.  I would suggest
> a simple TDSDUMP first, because it will tell you on one line the
> address & port it's connecting to, and the TDS version.
> --jkl
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