Can not connect to SQL Server from Ubuntu sqlcmd client I'm trying to connect to a SQL Server Express server from a Linux Ubuntu 16.04 computer. I Installed all SQL commad line utilities for the linux machine and follow instructions from Microsoft SQL Server on Linux docs.

When I run 

sqlcmd -S ip/SQLEXPRESS -U SA -P 1234


the command always returns the following error :


  Microsoft ODBC Driver 13 for SQL Server : Login timeout expired.
  Microsoft ODBC Driver 13 for SQL Server : TCP Provider: Error code 0x2AF9


I was able to run the same command from a Windows 10 computers and it works with no flaws. 

The linux computer can communicate to the server machine and SQL Server 1433 port. I test this with the linux nc command (netcat).

Linux nc command results:

nc -z -v -w5 192.168.0.1 1433



  Connection to 192.168.0.1 1433 port [tcp/ms-sql-s] succeeded!


Any suggestions or something missing?

I have tried changing the ports, parameter order etc... and Linux version of sqlcmd doesn't work.

I also tried including extra '/' character, because it is special on Linux. The new command line is sqlcmd -S ip//SQLEXPRESS -U SA -P 1234 but it doesn't work. It works faster but returns other error:


  Microsoft ODBC Driver 13 for SQL Server : TCP Provider: Error code 0x2746.


Instance name doesn't work neither. sqlcmd -S SERVER-NAME\\SQLEXPRESS -U SA -P 1234 or sqlcmd -H ipaddress -S SERVER-NAME\\SQLEXPRESS -U SA -P 1234 The command recognizes quotes so sqlcmd -S "SERVER-NAME\SQLEXPRESS" -U SA -P 1234. Nothing works.

The correct syntax is sqlcmd -S ip\\SQLEXPRESS -U SA -P 1234 with double '\'. It doesn't connect anyway. I have several days struggling with it and could not find a way to make this thing work.
I think the right command should be:
sqlcmd -S &lt;IP&gt;\\SQLEXPRESS,1433 -U SA