---
title: "Get Mutual Kerberos Authentication | Microsoft Docs"
ms.custom: ""
ms.date: "03/14/2017"
ms.prod: sql
ms.prod_service: "database-engine, sql-database, sql-data-warehouse, pdw"
ms.reviewer: ""
ms.technology: native-client
ms.topic: "reference"
ms.assetid: 64149fd4-239b-40e4-91e2-f9011f7d9f66
author: markingmyname
ms.author: maghan
monikerRange: ">=aps-pdw-2016||=azuresqldb-current||=azure-sqldw-latest||>=sql-server-2016||=sqlallproducts-allversions||>=sql-server-linux-2017||=azuresqldb-mi-current"
---
# Get Mutual Kerberos Authentication
[!INCLUDE[appliesto-ss-asdb-asdw-pdw-md](../../includes/appliesto-ss-asdb-asdw-pdw-md.md)]

  This sample shows how to get mutual Kerberos authentication by using ODBC in [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] Native Client.  
  
 This sample will not work with any version of [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] earlier than [!INCLUDE[ssKatmai](../../includes/sskatmai-md.md)].  
  
 For more information, see [Service Principal Name (SPN) Support in Client Connections](../../relational-databases/native-client/features/service-principal-name-spn-support-in-client-connections.md).  
  
## Example  
 If you will build and run this sample as a 32-bit application on a 64-bit operating system, you must create the ODBC data source with the ODBC Administrator in %windir%\SysWOW64\odbcad32.exe.  
  
 This sample connects to your computer's default [!INCLUDE[ssNoVersion](../../includes/ssnoversion-md.md)] instance. To connect to a named instance, change the definition of the ODBC data source to specify the instance using the following format: server\namedinstance. By default, [!INCLUDE[ssExpress](../../includes/ssexpress-md.md)] installs to a named instance.  
  
 Change "MyServer" to a machine name that has an instance of [!INCLUDE[ssKatmai](../../includes/sskatmai-md.md)] (or later).  
  
 You will also have to specify a customer-provided SPN. Change " CP_SPN " to a customer-provided SPN.  
  
 Compile with /EHsc, /D "_UNICODE", /D "UNICODE", and odbc32.lib. Make sure your INCLUDE environment variable includes the directory that contains sqlncli.h.  
  
```  
// compile with: /EHsc /D "_UNICODE" /D "UNICODE" odbc32.lib  
#define WIN32_LEAN_AND_MEAN  
#include <tchar.h>  
#include <windows.h>  
#include <stdio.h>  
#include <sql.h>  
#include <sqlext.h>  
  
#define _SQLNCLI_ODBC_  
#include <sqlncli.h>  
  
#define SUCCESS(x) (!((x) & 0xFFFE))  
  
#define CHKRC(stmt) do \  
                    { \  
                    rc = (stmt); \  
                    if (!SUCCESS(rc)) \  
                    throw (RETCODE) rc; \  
                    } while(0);  
  
void PrintError(SQLSMALLINT HandleType, SQLHANDLE Handle) {  
   RETCODE rc = SQL_SUCCESS;  
   SQLTCHAR szSqlState[6], szMessage[1024];  
   SQLSMALLINT i = 1, msgLen = 0;  
   SQLINTEGER NativeError;  
  
   do {  
      i = 1;  
      while (SQL_NO_DATA != (rc = SQLGetDiagRec(HandleType, Handle, i, szSqlState, &NativeError,   
         szMessage, sizeof(szMessage)/sizeof(SQLTCHAR), &msgLen)) && SUCCESS(rc)) {  
            _tprintf(_T("SQLState=%s, NativeError=%ld, Message=%s\r\n"), szSqlState, NativeError, szMessage);  
            i++;  
      }  
   }   
   while (SQL_NO_DATA != (rc = SQLMoreResults(Handle)) && SUCCESS(rc));  
}  
  
int _tmain(int argc, _TCHAR* argv[]) {  
   RETCODE rc = SQL_SUCCESS;  
   HENV henv = SQL_NULL_HENV;  
   HDBC hdbc = SQL_NULL_HDBC;  
   SQLHSTMT hstmt = SQL_NULL_HSTMT;  
   SQLTCHAR * pszConnection = _T("DRIVER={SQL Server Native Client 10.0};")  
      _T("Server=MyServer;")          // server with SQL Server 2008 (or later)  
      _T("Trusted_Connection=Yes;")  
      _T("ServerSPN=CP_SPN");    // customer-provided SPN  
  
   TCHAR szIntgAuthMethod[64];  
   SQLSMALLINT fMutuallyAuth = 0;  
  
   try {  
      CHKRC(SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HENV, &henv));  
      CHKRC(SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER)SQL_OV_ODBC3, 0));  
      CHKRC(SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc));  
      CHKRC(SQLDriverConnect( hdbc, NULL, pszConnection, SQL_NTS, NULL, 0, NULL, SQL_DRIVER_NOPROMPT));  
      CHKRC(SQLGetConnectAttr(hdbc, SQL_COPT_SS_INTEGRATED_AUTHENTICATION_METHOD, szIntgAuthMethod, sizeof(szIntgAuthMethod)/sizeof(szIntgAuthMethod[0]), NULL));  
      CHKRC(::SQLGetConnectAttrW(hdbc, SQL_COPT_SS_MUTUALLY_AUTHENTICATED, &fMutuallyAuth, SQL_IS_SMALLINT, NULL));  
  
      _tprintf(_T("Authentication method: %s\r\n"), szIntgAuthMethod);  
      _tprintf(_T("Mutually authenticated: %s\r\n"), fMutuallyAuth?_T("yes"):_T("no"));  
   }  
   catch (RETCODE retcode) {  
      rc = retcode;  
   }  
  
   if (!SUCCESS(rc)) {  
      if (hstmt)  
         PrintError(SQL_HANDLE_STMT, hstmt);  
      else if (hdbc)  
         PrintError(SQL_HANDLE_DBC, hdbc);  
      else if(henv)  
         PrintError(SQL_HANDLE_ENV, henv);  
   }  
  
   if (hstmt)  
      SQLFreeHandle(SQL_HANDLE_STMT, hstmt);  
   if (hdbc) {  
      SQLDisconnect(hdbc);  
      SQLFreeHandle(SQL_HANDLE_DBC, hdbc);  
   }  
   if (henv)  
      SQLFreeHandle(SQL_HANDLE_ENV, henv);  
}  
```