Wired issues regarding Kerberos authentication of SQL server driver for ODBC and JDBC

 1 SPN not match

ERROR: Server not found in Kerberos database

The default SPN generated by MS SQL ODBC driver is not what was registered on the KDC.

e.g. 

Server name: server1.example.com

REALM: EXMPLE.COM

Port: 5150

The default SPN generated by the driver is 

MSSQLSvc/server1.example.com:5150@EXAMPLE.COM

However, the SPN really was registered on the KDC is

 MSSQLSvc/server1.example.com@EXAMPLE.COM

So, to resolve this issue, the ODBC DSN and JDBC string have to include explicit ServerSPN as:

ServerSPN=MSSQLSvc/server1.example.com@EXAMPLE.COM;

2 Java Kerberos uses UDP by default

Error: No valid credentials provided. SocketTimeoutException: Receive timed out.

The Java Kerberos by default uses UDP to connect KDC, while the KDC may only listen on TCP.

To resolve this, add below line in /etc/krb5.conf:

[libdefaults]

udp_preference_limit = 1