Change a User's Password (w/o Active Directory)

Category:

Network/Internet

Type:

Snippets

Difficulty:

Advanced

Author:

Roman Bobik

Version Compatibility: Visual Basic 6

More information:

This function let you change a User's Password on a NT or 2000 computer without using Active Directory Services.

The Function takes 4 Parameters:

- Computer name
- User name
- Old password
- New password

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
Option Explicit Private Declare Function NetUserChangePassword _ Lib "Netapi32.dll" (ComputerName As Any, User As Any, _ OldPass As Any, NewPass As Any) As Long Private Const ERROR_ACCESS_DENIED = 5& Private Const ERROR_INVALID_PASSWORD = 86& Private Const NERR_InvalidComputer = 2351 Private Const NERR_NotPrimary = 2226 Private Const NERR_UserNotFound = 2221 Private Const NERR_PasswordTooShort = 2245 Private Const ERROR_CANT_ACCESS_DOMAIN_INFO = 1351

Code:

'Changes the Password for the user "User" on the 
'computer "Server" from "OldPassword" to "NewPassword"
Function ChangeUserPassword(ByVal Server As String, _
  ByVal User As String, ByVal OldPassword As String, _
  ByVal NewPassword As String) As String

Dim r As Long, msg As String

'Create Unicode-Arrays
Dim bComputer() As Byte:    bComputer = GetByteArray(Server)
Dim bUser() As Byte:        bUser = GetByteArray(User)
Dim bOldPassword() As Byte: bOldPassword = GetByteArray(OldPassword)
Dim bNewPassword() As Byte: bNewPassword = GetByteArray(NewPassword)
    
    'call API-Function
    r = NetUserChangePassword(bComputer(0), bUser(0), _
      bOldPassword(0), bNewPassword(0))
    
    'check return value and represent as string
    Select Case r 
        Case ERROR_ACCESS_DENIED:    msg = "Error: Access denied."
        Case ERROR_INVALID_PASSWORD: msg = "Error: Invalid password."
        Case NERR_InvalidComputer:   msg = "Fehler: Invalid Computer-/Domainname."
        Case NERR_NotPrimary:        msg = "Error: This operation can only performed on the primary domain controler."
        Case NERR_UserNotFound:      msg = "Error: User not found."
        Case NERR_PasswordTooShort:  msg = "Error: Password does not match Password-Restrictions. (Password to short, to long or has already been used by this user.)"
        Case ERROR_CANT_ACCESS_DOMAIN_INFO
                                     msg = "Error: Error accessing info for domain controler. Maybe the computer is not available or access was denied."
        Case 0:                      msg = "Operation performed successfully."
        Case Else:                   msg = "Error: Unexpected Error " & r & " occured."
    End Select
    
    ChangeUserPassword = msg
End Function

'Converts a Unicode-String to a Unicode-Byte-Array.
'Is used because VB always passes Strings as ANSI instead of Unicode.
Private Function GetByteArray(ByVal str As String) As Byte()
    Dim Buf() As Byte
    Buf = str
    ReDim Preserve Buf(Len(str) * 2 + 1)

GetByteArray = Buf
End Function