无法连接:Adaptive Server不可用或不存在

在尝试连接远程SQL Server时:

$tsql -S localhost -U myuser

我得到的错误如下:

locale is "en_US.UTF-8"
locale charset is "UTF-8"
using default charset "UTF-8"
Error 20009 (severity 9):
    Unable to connect: Adaptive Server is unavailable or does not exist
    OS error 61, "Connection refused"
There was a problem connecting to the server

输出$tsql -C如下:

Compile-time settings (established with the "configure" script)
                        Version: freetds v0.91
         freetds.conf directory: /usr/local/freetds/conf/freetds
 MS db-lib source compatibility: no
    Sybase binary compatibility: no
                  Thread safety: yes
                  iconv library: no
                    TDS version: 5.0
                          iODBC: no
                       unixodbc: no
          SSPI "trusted" logins: no
                       Kerberos: no

我为远程服务器创建了隧道,如:

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

这将本地端口1433转发到db_server.我测试过了.我的ssh隧道有效,因为我可以使用Navicat(1433上的localhost)连接到数据库.我可以通过端口1433 telnet localhost.