Are you using freetds? If you are, what is the content of your freetds.conf file? Where does it live? freetds has a good manual and, in it, it has a pretty large section on connecting to MS-SQL. I'd RTFM first.

For your reference, my .freetds.conf looks like:

[global]
   tds version = 4.2
   textsize = 10000
 
[MY_SERVER]
   host = 123.456.78.90
   port = 1433
[download]

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We are the carpenters and bricklayers of the Information Age.

Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.