Getting All Users in a Computer

Ibrahim Ersoy
12y
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Article

First we'll create a class to process WinApi calls.

This Class has been written by Michael Bright in 2003.Since then i've been using this code and extending it for network related needs.

using System;

using System.Runtime.InteropServices;
namespace GettingAllUsers
{
 
public class NetworkAPI
{
 
// USER_INFO_1 - Strucutre to hold obtained user information
[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
public struct USER_INFO_1
{
public string usri1_name; 
public string usri1_password; 
public int usri1_password_age; 
public int usri1_priv; 
public string usri1_home_dir; 
public string comment; 
public int usri1_flags; 
public string usri1_script_path;
} 
 
// USER_INFO_0 - Structure to hold Just Usernames
[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
public struct USER_INFO_0
{
public String Username;
}
 
// NetUserAdd - To Add Users to a local machine or Network
[DllImport("Netapi32.dll")]
public extern static int NetUserAdd([MarshalAs(UnmanagedType.LPWStr)] string servername, int level, ref USER_INFO_1 buf, int parm_err);
 
// NetUserDel - To delete Users from a local machine or Network
[DllImport("Netapi32.dll")]
public extern static int NetUserDel([MarshalAs(UnmanagedType.LPWStr)] string servername, [MarshalAs(UnmanagedType.LPWStr)] string username);
 
// NetUserGetInfo - Returns to a struct Information about the specified user
[DllImport("Netapi32.dll")]
public extern static int NetUserGetInfo([MarshalAs(UnmanagedType.LPWStr)] string servername,[MarshalAs(UnmanagedType.LPWStr)] string username,int level,out IntPtr bufptr);
 
// NetUserSetInfo - Allows us to modify User information
[DllImport("Netapi32.dll")]
public extern static int NetUserSetInfo([MarshalAs(UnmanagedType.LPWStr)] string servername,[MarshalAs(UnmanagedType.LPWStr)] string username,int level,ref USER_INFO_1 buf, int error);
 
// NetUserChangePassword - Allows us to change a users password providing we have it
[DllImport("Netapi32.dll")]
public extern static int NetUserChangePassword([MarshalAs(UnmanagedType.LPWStr)] string domainname,[MarshalAs(UnmanagedType.LPWStr)] string username,[MarshalAs(UnmanagedType.LPWStr)] string oldpassword,[MarshalAs(UnmanagedType.LPWStr)] string newpassword);
 
// NetUserEnum - Obtains a list of all users on local machine or network
[DllImport("Netapi32.dll")]
public extern static int NetUserEnum(string servername, int level, int filter, out IntPtr bufptr, int prefmaxlen, out int entriesread, out int totalentries, out int resume_handle);
 
// NetAPIBufferFree - Used to clear the Network buffer after NetUserEnum
[DllImport("Netapi32.dll")]
public extern static int NetApiBufferFree(IntPtr Buffer);
 
public NetworkAPI()
{
//
// TODO: Add constructor logic here
//
}
}
}
Add a ListBox in your form and then,Later inside your main application create a function:
public void EnumerateUsers()
{
int EntriesRead;
int TotalEntries;
int Resume;
listBox1.Items.Clear();
 
IntPtr bufPtr;
 
NetworkAPI.NetUserEnum(null, 0, 2, out bufPtr, -1, out EntriesRead, out TotalEntries, out Resume);
 
if (EntriesRead > 0)
{
NetworkAPI.USER_INFO_0[] Users = new NetworkAPI.USER_INFO_0[EntriesRead];
IntPtr iter = bufPtr;
for (int i = 0; i < EntriesRead; i++)
{
Users[i] = (NetworkAPI.USER_INFO_0)Marshal.PtrToStructure(iter, typeof(NetworkAPI.USER_INFO_0));
iter = (IntPtr)((int)iter + Marshal.SizeOf(typeof(NetworkAPI.USER_INFO_0)));
listBox1.Items.Add(Users[i].Username);
 
}
NetworkAPI.NetApiBufferFree(bufPtr);
}
listBox1.SelectedIndex = 0;
 
 
}
Now just call EnumerateUsers inside Form_Load to populate them in your listbox at startupprivate void Form1_Load(object sender, EventArgs e)
{
EnumerateUsers();
}
And run it!Hope that helps!