We've run into an interesting situation that needs solving, and my searches have turned up nill. I therefore appeal to the SO community for help.
The issue is this: we have a need to programmatically access a shared file that is not in our domain, and is not within a trusted external domain via remote file sharing / UNC. Naturally, we need to supply credentials to the remote machine.
Typically, one solves this problem in one of two ways:
NET USE command or the Win32 functions that duplicate NET USE. For various and sundry reasons, our security / network architects have rejected the first two approaches. The second approach is obviously a security hole; if the remote computer is compromised, the local computer is now at risk. The first approach is unsatisfactory because the newly mounted drive is a shared resource available to other programs on the local computer during file access by the program. Even though it's quite possible to make this temporary, it's still a hole in their opinion.
They're open to the third option, but the remote network admins insist on SFTP rather than FTPS, and FtpWebRequest only supports FTPS. SFTP is the more firewall-friendly option and there are a couple libraries I could use for that approach, but I'd prefer to reduce my dependencies if I can.
I've searched MSDN for either a managed or a win32 means of using remote file sharing, but I have failed to come up with anything useful.
And so I ask: Is there another way? Did I miss a super-secret win32 function that does what I want? Or must I pursue some variant of option 3?
This question is related to
c#
windows
unc
file-sharing
Most SFTP servers support SCP as well which can be a lot easier to find libraries for. You could even just call an existing client from your code like pscp included with PuTTY.
If the type of file you're working with is something simple like a text or XML file, you could even go so far as to write your own client/server implementation to manipulate the file using something like .NET Remoting or web services.
For people looking for a quick solution, you can use the NetworkShareAccesser I wrote recently (based on this answer (thanks so much!)):
Usage:
using (NetworkShareAccesser.Access(REMOTE_COMPUTER_NAME, DOMAIN, USER_NAME, PASSWORD))
{
File.Copy(@"C:\Some\File\To\copy.txt", @"\\REMOTE-COMPUTER\My\Shared\Target\file.txt");
}
WARNING: Please make absolutely sure, that Dispose of the NetworkShareAccesser is called (even if you app crashes!), otherwise an open connection will remain on Windows. You can see all open connections by opening the cmd prompt and enter net use.
The Code:
/// <summary>
/// Provides access to a network share.
/// </summary>
public class NetworkShareAccesser : IDisposable
{
private string _remoteUncName;
private string _remoteComputerName;
public string RemoteComputerName
{
get
{
return this._remoteComputerName;
}
set
{
this._remoteComputerName = value;
this._remoteUncName = @"\\" + this._remoteComputerName;
}
}
public string UserName
{
get;
set;
}
public string Password
{
get;
set;
}
#region Consts
private const int RESOURCE_CONNECTED = 0x00000001;
private const int RESOURCE_GLOBALNET = 0x00000002;
private const int RESOURCE_REMEMBERED = 0x00000003;
private const int RESOURCETYPE_ANY = 0x00000000;
private const int RESOURCETYPE_DISK = 0x00000001;
private const int RESOURCETYPE_PRINT = 0x00000002;
private const int RESOURCEDISPLAYTYPE_GENERIC = 0x00000000;
private const int RESOURCEDISPLAYTYPE_DOMAIN = 0x00000001;
private const int RESOURCEDISPLAYTYPE_SERVER = 0x00000002;
private const int RESOURCEDISPLAYTYPE_SHARE = 0x00000003;
private const int RESOURCEDISPLAYTYPE_FILE = 0x00000004;
private const int RESOURCEDISPLAYTYPE_GROUP = 0x00000005;
private const int RESOURCEUSAGE_CONNECTABLE = 0x00000001;
private const int RESOURCEUSAGE_CONTAINER = 0x00000002;
private const int CONNECT_INTERACTIVE = 0x00000008;
private const int CONNECT_PROMPT = 0x00000010;
private const int CONNECT_REDIRECT = 0x00000080;
private const int CONNECT_UPDATE_PROFILE = 0x00000001;
private const int CONNECT_COMMANDLINE = 0x00000800;
private const int CONNECT_CMD_SAVECRED = 0x00001000;
private const int CONNECT_LOCALDRIVE = 0x00000100;
#endregion
#region Errors
private const int NO_ERROR = 0;
private const int ERROR_ACCESS_DENIED = 5;
private const int ERROR_ALREADY_ASSIGNED = 85;
private const int ERROR_BAD_DEVICE = 1200;
private const int ERROR_BAD_NET_NAME = 67;
private const int ERROR_BAD_PROVIDER = 1204;
private const int ERROR_CANCELLED = 1223;
private const int ERROR_EXTENDED_ERROR = 1208;
private const int ERROR_INVALID_ADDRESS = 487;
private const int ERROR_INVALID_PARAMETER = 87;
private const int ERROR_INVALID_PASSWORD = 1216;
private const int ERROR_MORE_DATA = 234;
private const int ERROR_NO_MORE_ITEMS = 259;
private const int ERROR_NO_NET_OR_BAD_PATH = 1203;
private const int ERROR_NO_NETWORK = 1222;
private const int ERROR_BAD_PROFILE = 1206;
private const int ERROR_CANNOT_OPEN_PROFILE = 1205;
private const int ERROR_DEVICE_IN_USE = 2404;
private const int ERROR_NOT_CONNECTED = 2250;
private const int ERROR_OPEN_FILES = 2401;
#endregion
#region PInvoke Signatures
[DllImport("Mpr.dll")]
private static extern int WNetUseConnection(
IntPtr hwndOwner,
NETRESOURCE lpNetResource,
string lpPassword,
string lpUserID,
int dwFlags,
string lpAccessName,
string lpBufferSize,
string lpResult
);
[DllImport("Mpr.dll")]
private static extern int WNetCancelConnection2(
string lpName,
int dwFlags,
bool fForce
);
[StructLayout(LayoutKind.Sequential)]
private class NETRESOURCE
{
public int dwScope = 0;
public int dwType = 0;
public int dwDisplayType = 0;
public int dwUsage = 0;
public string lpLocalName = "";
public string lpRemoteName = "";
public string lpComment = "";
public string lpProvider = "";
}
#endregion
/// <summary>
/// Creates a NetworkShareAccesser for the given computer name. The user will be promted to enter credentials
/// </summary>
/// <param name="remoteComputerName"></param>
/// <returns></returns>
public static NetworkShareAccesser Access(string remoteComputerName)
{
return new NetworkShareAccesser(remoteComputerName);
}
/// <summary>
/// Creates a NetworkShareAccesser for the given computer name using the given domain/computer name, username and password
/// </summary>
/// <param name="remoteComputerName"></param>
/// <param name="domainOrComuterName"></param>
/// <param name="userName"></param>
/// <param name="password"></param>
public static NetworkShareAccesser Access(string remoteComputerName, string domainOrComuterName, string userName, string password)
{
return new NetworkShareAccesser(remoteComputerName,
domainOrComuterName + @"\" + userName,
password);
}
/// <summary>
/// Creates a NetworkShareAccesser for the given computer name using the given username (format: domainOrComputername\Username) and password
/// </summary>
/// <param name="remoteComputerName"></param>
/// <param name="userName"></param>
/// <param name="password"></param>
public static NetworkShareAccesser Access(string remoteComputerName, string userName, string password)
{
return new NetworkShareAccesser(remoteComputerName,
userName,
password);
}
private NetworkShareAccesser(string remoteComputerName)
{
RemoteComputerName = remoteComputerName;
this.ConnectToShare(this._remoteUncName, null, null, true);
}
private NetworkShareAccesser(string remoteComputerName, string userName, string password)
{
RemoteComputerName = remoteComputerName;
UserName = userName;
Password = password;
this.ConnectToShare(this._remoteUncName, this.UserName, this.Password, false);
}
private void ConnectToShare(string remoteUnc, string username, string password, bool promptUser)
{
NETRESOURCE nr = new NETRESOURCE
{
dwType = RESOURCETYPE_DISK,
lpRemoteName = remoteUnc
};
int result;
if (promptUser)
{
result = WNetUseConnection(IntPtr.Zero, nr, "", "", CONNECT_INTERACTIVE | CONNECT_PROMPT, null, null, null);
}
else
{
result = WNetUseConnection(IntPtr.Zero, nr, password, username, 0, null, null, null);
}
if (result != NO_ERROR)
{
throw new Win32Exception(result);
}
}
private void DisconnectFromShare(string remoteUnc)
{
int result = WNetCancelConnection2(remoteUnc, CONNECT_UPDATE_PROFILE, false);
if (result != NO_ERROR)
{
throw new Win32Exception(result);
}
}
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
/// <filterpriority>2</filterpriority>
public void Dispose()
{
this.DisconnectFromShare(this._remoteUncName);
}
}
I looked to MS to find the answers. The first solution assumes the user account running the application process has access to the shared folder or drive (Same domain). Make sure your DNS is resolved or try using IP address. Simply do the following:
DirectoryInfo di = new DirectoryInfo(PATH);
var files = di.EnumerateFiles("*.*", SearchOption.AllDirectories);
If you want across different domains .NET 2.0 with credentials follow this model:
WebRequest req = FileWebRequest.Create(new Uri(@"\\<server Name>\Dir\test.txt"));
req.Credentials = new NetworkCredential(@"<Domain>\<User>", "<Password>");
req.PreAuthenticate = true;
WebResponse d = req.GetResponse();
FileStream fs = File.Create("test.txt");
// here you can check that the cast was successful if you want.
fs = d.GetResponseStream() as FileStream;
fs.Close();
Rather than WNetUseConnection, I would recommend NetUseAdd. WNetUseConnection is a legacy function that's been superceded by WNetUseConnection2 and WNetUseConnection3, but all of those functions create a network device that's visible in Windows Explorer. NetUseAdd is the equivalent of calling net use in a DOS prompt to authenticate on a remote computer.
If you call NetUseAdd then subsequent attempts to access the directory should succeed.
While I don't know myself, I would certainly hope that #2 is incorrect...I'd like to think that Windows isn't going to AUTOMATICALLY give out my login information (least of all my password!) to any machine, let alone one that isn't part of my trust.
Regardless, have you explored the impersonation architecture? Your code is going to look similar to this:
using (System.Security.Principal.WindowsImpersonationContext context = System.Security.Principal.WindowsIdentity.Impersonate(token))
{
// Do network operations here
context.Undo();
}
In this case, the token variable is an IntPtr. In order to get a value for this variable, you'll have to call the unmanaged LogonUser Windows API function. A quick trip to pinvoke.net gives us the following signature:
[System.Runtime.InteropServices.DllImport("advapi32.dll", SetLastError = true)]
public static extern bool LogonUser(
string lpszUsername,
string lpszDomain,
string lpszPassword,
int dwLogonType,
int dwLogonProvider,
out IntPtr phToken
);
Username, domain, and password should seem fairly obvious. Have a look at the various values that can be passed to dwLogonType and dwLogonProvider to determine the one that best suits your needs.
This code hasn't been tested, as I don't have a second domain here where I can verify, but this should hopefully put you on the right track.
AFAIK, you don't need to map the UNC path to a drive letter in order to establish credentials for a server. I regularly used batch scripts like:
net use \\myserver /user:username password
:: do something with \\myserver\the\file\i\want.xml
net use /delete \\my.server.com
However, any program running on the same account as your program would still be able to access everything that username:password has access to. A possible solution could be to isolate your program in its own local user account (the UNC access is local to the account that called NET USE).
Note: Using SMB accross domains is not quite a good use of the technology, IMO. If security is that important, the fact that SMB lacks encryption is a bit of a damper all by itself.
Here a minimal POC class w/ all the cruft removed
using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
public class UncShareWithCredentials : IDisposable
{
private string _uncShare;
public UncShareWithCredentials(string uncShare, string userName, string password)
{
var nr = new Native.NETRESOURCE
{
dwType = Native.RESOURCETYPE_DISK,
lpRemoteName = uncShare
};
int result = Native.WNetUseConnection(IntPtr.Zero, nr, password, userName, 0, null, null, null);
if (result != Native.NO_ERROR)
{
throw new Win32Exception(result);
}
_uncShare = uncShare;
}
public void Dispose()
{
if (!string.IsNullOrEmpty(_uncShare))
{
Native.WNetCancelConnection2(_uncShare, Native.CONNECT_UPDATE_PROFILE, false);
_uncShare = null;
}
}
private class Native
{
public const int RESOURCETYPE_DISK = 0x00000001;
public const int CONNECT_UPDATE_PROFILE = 0x00000001;
public const int NO_ERROR = 0;
[DllImport("mpr.dll")]
public static extern int WNetUseConnection(IntPtr hwndOwner, NETRESOURCE lpNetResource, string lpPassword, string lpUserID,
int dwFlags, string lpAccessName, string lpBufferSize, string lpResult);
[DllImport("mpr.dll")]
public static extern int WNetCancelConnection2(string lpName, int dwFlags, bool fForce);
[StructLayout(LayoutKind.Sequential)]
public class NETRESOURCE
{
public int dwScope;
public int dwType;
public int dwDisplayType;
public int dwUsage;
public string lpLocalName;
public string lpRemoteName;
public string lpComment;
public string lpProvider;
}
}
}
You can directly use \\server\share\folder w/ WNetUseConnection, no need to strip it to \\server part only beforehand.
im attach my vb.net code based on brian reference
Imports System.ComponentModel
Imports System.Runtime.InteropServices
Public Class PinvokeWindowsNetworking
Const NO_ERROR As Integer = 0
Private Structure ErrorClass
Public num As Integer
Public message As String
Public Sub New(ByVal num As Integer, ByVal message As String)
Me.num = num
Me.message = message
End Sub
End Structure
Private Shared ERROR_LIST As ErrorClass() = New ErrorClass() {
New ErrorClass(5, "Error: Access Denied"),
New ErrorClass(85, "Error: Already Assigned"),
New ErrorClass(1200, "Error: Bad Device"),
New ErrorClass(67, "Error: Bad Net Name"),
New ErrorClass(1204, "Error: Bad Provider"),
New ErrorClass(1223, "Error: Cancelled"),
New ErrorClass(1208, "Error: Extended Error"),
New ErrorClass(487, "Error: Invalid Address"),
New ErrorClass(87, "Error: Invalid Parameter"),
New ErrorClass(1216, "Error: Invalid Password"),
New ErrorClass(234, "Error: More Data"),
New ErrorClass(259, "Error: No More Items"),
New ErrorClass(1203, "Error: No Net Or Bad Path"),
New ErrorClass(1222, "Error: No Network"),
New ErrorClass(1206, "Error: Bad Profile"),
New ErrorClass(1205, "Error: Cannot Open Profile"),
New ErrorClass(2404, "Error: Device In Use"),
New ErrorClass(2250, "Error: Not Connected"),
New ErrorClass(2401, "Error: Open Files")}
Private Shared Function getErrorForNumber(ByVal errNum As Integer) As String
For Each er As ErrorClass In ERROR_LIST
If er.num = errNum Then Return er.message
Next
Try
Throw New Win32Exception(errNum)
Catch ex As Exception
Return "Error: Unknown, " & errNum & " " & ex.Message
End Try
Return "Error: Unknown, " & errNum
End Function
<DllImport("Mpr.dll")>
Private Shared Function WNetUseConnection(ByVal hwndOwner As IntPtr, ByVal lpNetResource As NETRESOURCE, ByVal lpPassword As String, ByVal lpUserID As String, ByVal dwFlags As Integer, ByVal lpAccessName As String, ByVal lpBufferSize As String, ByVal lpResult As String) As Integer
End Function
<DllImport("Mpr.dll")>
Private Shared Function WNetCancelConnection2(ByVal lpName As String, ByVal dwFlags As Integer, ByVal fForce As Boolean) As Integer
End Function
<StructLayout(LayoutKind.Sequential)>
Private Class NETRESOURCE
Public dwScope As Integer = 0
Public dwType As Integer = 0
Public dwDisplayType As Integer = 0
Public dwUsage As Integer = 0
Public lpLocalName As String = ""
Public lpRemoteName As String = ""
Public lpComment As String = ""
Public lpProvider As String = ""
End Class
Public Shared Function connectToRemote(ByVal remoteUNC As String, ByVal username As String, ByVal password As String) As String
Return connectToRemote(remoteUNC, username, password, False)
End Function
Public Shared Function connectToRemote(ByVal remoteUNC As String, ByVal username As String, ByVal password As String, ByVal promptUser As Boolean) As String
Dim nr As NETRESOURCE = New NETRESOURCE()
nr.dwType = ResourceTypes.Disk
nr.lpRemoteName = remoteUNC
Dim ret As Integer
If promptUser Then
ret = WNetUseConnection(IntPtr.Zero, nr, "", "", Connects.Interactive Or Connects.Prompt, Nothing, Nothing, Nothing)
Else
ret = WNetUseConnection(IntPtr.Zero, nr, password, username, 0, Nothing, Nothing, Nothing)
End If
If ret = NO_ERROR Then Return Nothing
Return getErrorForNumber(ret)
End Function
Public Shared Function disconnectRemote(ByVal remoteUNC As String) As String
Dim ret As Integer = WNetCancelConnection2(remoteUNC, Connects.UpdateProfile, False)
If ret = NO_ERROR Then Return Nothing
Return getErrorForNumber(ret)
End Function
Enum Resources As Integer
Connected = &H1
GlobalNet = &H2
Remembered = &H3
End Enum
Enum ResourceTypes As Integer
Any = &H0
Disk = &H1
Print = &H2
End Enum
Enum ResourceDisplayTypes As Integer
Generic = &H0
Domain = &H1
Server = &H2
Share = &H3
File = &H4
Group = &H5
End Enum
Enum ResourceUsages As Integer
Connectable = &H1
Container = &H2
End Enum
Enum Connects As Integer
Interactive = &H8
Prompt = &H10
Redirect = &H80
UpdateProfile = &H1
CommandLine = &H800
CmdSaveCred = &H1000
LocalDrive = &H100
End Enum
End Class
how to use it
Dim login = PinvokeWindowsNetworking.connectToRemote("\\ComputerName", "ComputerName\UserName", "Password")
If IsNothing(login) Then
'do your thing on the shared folder
PinvokeWindowsNetworking.disconnectRemote("\\ComputerName")
End If
Source: Stackoverflow.com