NetSessionEnum function

Provides information about sessions established on a server.

Syntax

NET_API_STATUS NET_API_FUNCTION NetSessionEnum(
  LMSTR   servername,
  LMSTR   UncClientName,
  LMSTR   username,
  DWORD   level,
  LPBYTE  *bufptr,
  DWORD   prefmaxlen,
  LPDWORD entriesread,
  LPDWORD totalentries,
  LPDWORD resume_handle
);

Parameters

servername

Pointer to a string that specifies the DNS or NetBIOS name of the remote server on which the function is to execute. If this parameter is NULL, the local computer is used.

UncClientName

Pointer to a string that specifies the name of the computer session for which information is to be returned. If this parameter is NULL, NetSessionEnum returns information for all computer sessions on the server.

username

Pointer to a string that specifies the name of the user for which information is to be returned. If this parameter is NULL, NetSessionEnum returns information for all users.

level

Specifies the information level of the data. This parameter can be one of the following values.

Value Meaning
0
Return the name of the computer that established the session. The bufptr parameter points to an array of SESSION_INFO_0 structures.
1
Return the name of the computer, name of the user, and open files, pipes, and devices on the computer. The bufptr parameter points to an array of SESSION_INFO_1 structures.
2
In addition to the information indicated for level 1, return the type of client and how the user established the session. The bufptr parameter points to an array of SESSION_INFO_2 structures.
10
Return the name of the computer, name of the user, and active and idle times for the session. The bufptr parameter points to an array of SESSION_INFO_10 structures.
502
Return the name of the computer; name of the user; open files, pipes, and devices on the computer; and the name of the transport the client is using. The bufptr parameter points to an array of SESSION_INFO_502 structures.

bufptr

Pointer to the buffer that receives the data. The format of this data depends on the value of the level parameter.

This buffer is allocated by the system and must be freed using the NetApiBufferFree function. Note that you must free the buffer even if the function fails with ERROR_MORE_DATA.

prefmaxlen

Specifies the preferred maximum length of returned data, in bytes. If you specify MAX_PREFERRED_LENGTH, the function allocates the amount of memory required for the data. If you specify another value in this parameter, it can restrict the number of bytes that the function returns. If the buffer size is insufficient to hold all entries, the function returns ERROR_MORE_DATA. For more information, see Network Management Function Buffers and Network Management Function Buffer Lengths.

entriesread

Pointer to a value that receives the count of elements actually enumerated.

totalentries

Pointer to a value that receives the total number of entries that could have been enumerated from the current resume position. Note that applications should consider this value only as a hint.

resume_handle

Pointer to a value that contains a resume handle which is used to continue an existing session search. The handle should be zero on the first call and left unchanged for subsequent calls. If resume_handle is NULL, no resume handle is stored.

Return Value

If the function succeeds, the return value is NERR_Success.

If the function fails, the return value can be one of the following error codes.

Return code Description
ERROR_ACCESS_DENIED
The user does not have access to the requested information.
ERROR_INVALID_LEVEL
The value specified for the level parameter is not valid.
ERROR_INVALID_PARAMETER
The specified parameter is not valid.
ERROR_MORE_DATA
More entries are available. Specify a large enough buffer to receive all entries.
ERROR_NOT_ENOUGH_MEMORY
Insufficient memory is available.
NERR_ClientNameNotFound
A session does not exist with the computer name.
NERR_InvalidComputer
The computer name is not valid.
NERR_UserNotFound
The user name could not be found.

Remarks

Only members of the Administrators or Server Operators local group can successfully execute the NetSessionEnum function at level 1 or level 2. No special group membership is required for level 0 or level 10 calls.

If you are programming for Active Directory, you may be able to call certain Active Directory Service Interface (ADSI) methods to achieve the same functionality you can achieve by calling the network management session functions. For more information, see IADsSession and IADsFileServiceOperations.

Examples

The following code sample demonstrates how to retrieve information about current sessions using a call to the NetSessionEnum function. The sample calls NetSessionEnum, specifying information level 10 ( SESSION_INFO_10). The sample loops through the entries and prints the retrieved information. Finally, the code prints the total number of sessions enumerated and frees the memory allocated for the information buffer.

C++
#ifndef UNICODE
#define UNICODE
#endif
#pragma comment(lib, "Netapi32.lib")

#include <stdio.h> #include <assert.h> #include <windows.h> #include <lm.h>

int wmain(int argc, wchar_t *argv[]) { LPSESSION_INFO_10 pBuf = NULL; LPSESSION_INFO_10 pTmpBuf; DWORD dwLevel = 10; DWORD dwPrefMaxLen = MAX_PREFERRED_LENGTH; DWORD dwEntriesRead = 0; DWORD dwTotalEntries = 0; DWORD dwResumeHandle = 0; DWORD i; DWORD dwTotalCount = 0; LPTSTR pszServerName = NULL; LPTSTR pszClientName = NULL; LPTSTR pszUserName = NULL; NET_API_STATUS nStatus; // // Check command line arguments. // if (argc > 4) { wprintf(L"Usage: %s [\\ServerName] [\\ClientName] [UserName]\n", argv[0]); exit(1); }

if (argc >= 2) pszServerName = argv[1];

if (argc >= 3) pszClientName = argv[2];

if (argc == 4) pszUserName = argv[3]; // // Call the NetSessionEnum function, specifying level 10. // do // begin do { nStatus = NetSessionEnum(pszServerName, pszClientName, pszUserName, dwLevel, (LPBYTE*)&pBuf, dwPrefMaxLen, &dwEntriesRead, &dwTotalEntries, &dwResumeHandle); // // If the call succeeds, // if ((nStatus == NERR_Success) || (nStatus == ERROR_MORE_DATA)) { if ((pTmpBuf = pBuf) != NULL) { // // Loop through the entries. // for (i = 0; (i < dwEntriesRead); i++) { assert(pTmpBuf != NULL);

           if (pTmpBuf == NULL)
           {
              fprintf(stderr, "An access violation has occurred\n");
              break;
           }
           //
           // Print the retrieved data. 
           //
           wprintf(L"\n\tClient: %s\n", pTmpBuf-&gt;sesi10_cname);
           wprintf(L"\tUser:   %s\n", pTmpBuf-&gt;sesi10_username);
           printf("\tActive: %d\n", pTmpBuf-&gt;sesi10_time);
           printf("\tIdle:   %d\n", pTmpBuf-&gt;sesi10_idle_time);

           pTmpBuf++;
           dwTotalCount++;
        }
     }
  }
  //
  // Otherwise, indicate a system error.
  //
  else
     fprintf(stderr, "A system error has occurred: %d\n", nStatus);
  //
  // Free the allocated memory.
  //
  if (pBuf != NULL)
  {
     NetApiBufferFree(pBuf);
     pBuf = NULL;
  }

} // // Continue to call NetSessionEnum while // there are more entries. // while (nStatus == ERROR_MORE_DATA); // end do

// Check again for an allocated buffer. // if (pBuf != NULL) NetApiBufferFree(pBuf); // // Print the final count of sessions enumerated. // fprintf(stderr, "\nTotal of %d entries enumerated\n", dwTotalCount);

return 0; }

Requirements

   
Windows version Windows XP [desktop apps only] Windows Server 2003 [desktop apps only]
Target Platform Windows
Header lmshare.h (include Lm.h)
Library Netapi32.lib
DLL Netapi32.dll

See Also

NetSessionGetInfo

Network Management Functions

Network Management Overview

SESSION_INFO_0

SESSION_INFO_1

SESSION_INFO_10

SESSION_INFO_2

SESSION_INFO_502

Session Functions