FULL PRODUCT VERSION :
java version "1.6.0_29"
Java(TM) SE Runtime Environment (build 1.6.0_29-b11)
Java HotSpot(TM) 64-Bit Server VM (build 20.4-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7600]

EXTRA RELEVANT SYSTEM CONFIGURATION :
Microsoft JDBC Driver 2.0 / 3.0 / 4.0 CTP 3
SQL Server 2008R2

A DESCRIPTION OF THE PROBLEM :
Creating a JDBC connection through Microsoft JDBC Driver 2.0, 3.0, 4.0 CTP 3, or jTDS 1.2.5 driver to a Microsoft SQL server 2008R2 database using JDK 1.6.0_29 results in an indefinite wait for a connection. This worked fine on all previous versions from 1.6.0_27.

Interrupting the thread does not work, it has to be stopped.

REGRESSION. Last worked in version 6u26

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run supported source with one of the mentioned Microsoft SQL Server drivers.
With version 1.6.0_29 this program will not terminate. With any other JVM version this will create a usable connection.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
  To see a line in console "Connected to database:"
ACTUAL -
None, program will not terminate, and needs to be stopped forcibly.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Stakctrace at the moment of thread stop:

    at java.net.SocketInputStream.socketRead0(Native Method) ~[na:1.6.0_29]
    at java.net.SocketInputStream.read(Unknown Source) ~[na:1.6.0_29]
    at com.microsoft.sqlserver.jdbc.TDSChannel.read(IOBuffer.java:1647) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.TDSReader.readPacket(IOBuffer.java:3694) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.TDSCommand.startResponse(IOBuffer.java:5026) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.TDSCommand.startResponse(IOBuffer.java:4978) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection$1ConnectionCommand.doExecute(SQLServerConnection.java:1441) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:4575) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1400) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectionCommand(SQLServerConnection.java:1446) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.logon(SQLServerConnection.java:1907) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.access$000(SQLServerConnection.java:41) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection$LogonCommand.doExecute(SQLServerConnection.java:1893) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:4575) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1400) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectHelper(SQLServerConnection.java:1045) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.login(SQLServerConnection.java:817) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.connect(SQLServerConnection.java:700) ~[jdbc4-driver-3.0.jar:na]
    at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect(SQLServerDriver.java:842) ~[jdbc4-driver-3.0.jar:na]
    at java.sql.DriverManager.getConnection(Unknown Source) ~[na:1.6.0_29]
    at java.sql.DriverManager.getConnection(Unknown Source) ~[na:1.6.0_29]

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class JdbcBug {

public static void main(String[] args) throws SQLException {
Properties connectionProps = new Properties();
connectionProps.put("user", "my_username");
connectionProps.put("password", "my_password");

Connection conn = DriverManager.getConnection("jdbc:sqlserver://localhost:1433",
connectionProps);
System.out.println("Connected to database: " + conn);
}
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Revert to Java 1.6.0_27 or earlier version, or upgrade to 1.7.0_01. Or switch Microsoft database server. SQL Server 2008 , 2005, 2000 all work.
From http://stackoverflow.com/questions/7841411/driver-getconnection-hangs-using-sqlserver-driver-and-java-1-6-0-29/

    * OS: Tested on both redhat 6.1 and Windows 2008
    * Driver: MS SQL Server JDBC Driver version 3.0.1301.101
    * Java Versions: 1.6.0_26 and 1.6.0_29

    Windows 7 x64, JDK 1.6.0_29, SQL Express 2008 R2 (10.50.1790), using
    sqljdbc4.jar, and it hangs on getConnection.

    Reproduced with SQL server 2008R2. SQL 2005 & 2008 work normally

VERY IMPORTANT HERE:

    Works on 7.1, but not on 6u29.