VB.Net File.Copy/File.Move with different credentials - vb.net

Ideally I'd like to be able to copy/move between an accessible folder on my local drive and a network share that I don't have permission to access (but the application would).
I am using impersonation to give me access to the files in the network share but using System.IO File.Move or File.Copy forces me to use the same credentials for each location. Is there a way around this?

What I believe you could do is something like this.
Do the impersonation to allow the selection of files. Copy the files to a location that the app can get to.
Stop the impersonation then have the application copy the file from the temp location to the desired end result.
We have done this before in our applications, it isn't elegant, but it works perfectly!

We've done something similar to what Mitchel Sellers is doing, except that we don't have a location that both identities can read from. We are reading blocks of data into memory using the local context and writing them out while impersonating the remote user.

Related

Copy files to local drive that requires different credentials

I've seen a lot of answers on copying files that use code to set a network share, with credentials, to copy to somewhere else. However I need a solution that will allow a user to copy from a network share they already have access for, to a local drive they don't have access to.
We run RDS servers and have locked down direct access to the local C:/ drive on the servers. We have been given a 3rd party program that needs to read data files that must be stored in a fixed path on the C:/ drive. These data files are updated once a month. Our users have read access but we do not want to give them direct write access to the root C:/ drive.
I need to write a piece of vb.net, or command line code in .bat file that will copy files to the Local C:/ whilst providing the details of a service account to provide the access.
As mentioned I've seen a lot about setting up a mapping to shared folder and passing creds, however we don't want to set the C:/ as mapped shared drive in this instance.
You don't want the user having access to the C Drive in general, is there any particular reason the permissions on the particular subfolder the files are going to can't have overriding permissions to allow writing to just that folder?
If that will not work, first thought that comes to mind is having a helper program that can be ran under a different user that does have that access. Set up an intermediate folder the user can write to, the program that they can launch drops the files into a folder they have access to. Helper program watches for files in the intermediate folder, moves them to where they need to be.
Set up would need to include adding a user that does have access to both locations, and then adding to task manager to launch the helper program under that other user at login.

Failed to update database because the database is read only

This message appears every time I try to save the data to the DB.
Failed to update database because the database is read only
Note: This error comes only when the application is installed to C drive.
Front End: VB.NET
Back End:SQL Server
Is there any way to overcome this issue?
Or any way to restrict the user from installing the application on C drive?
I would check the file system privileges. I suppose you talk about an SQL server file database. You receive the message because the account trying to access your file database does not have the file system permissions to do so.
In order to confirm my suggestion, you allow everyone to access the specific directory with full permissions.
Then, you have to check what is the account trying to do the actual access. Probably it's a system account (user ASPNET or NETWORK SERVICE). You have to give the respective permissions to the specific account.
Then, restart IIS.
If you want to do this for a distributed stand-alone application. Then these permissions would have to change on each machine where the program would be installed. In order to avoid putting users in such a fuss, the setup program should do it. I am not an expert on setup programs, but even the simplest ones would give you the option to do it, after asking the system adminstrator's approval. I suppose you could build a custom action during the setup program which would change the specific folder's permissions, perhaps by using xcacls.exe.
Hope I helped!

Best Method for online update

I was trying to work out the best method of synchronising an update of files via vb.net. I want to automatically update some files in a few folders from an FTP site to a local drive. This would ideally be the same folder structure, but on a specified local folder. I have looked at the FTP methods in .net and am able to transfer individual files successfully, but wondered if there was an elegant method to collecting the entire folder from the FTP and it's contents to be re-created locally. I have established the reading of an XML via linq from the ftp to establish an update single and decide whether the local machine is up-to-date or not, it's just the transfer of the folders that i'm stuck on as it's different to using a IO method.
Can any gurus confirm that this is the best way of approaching this task?
cheers CS
Your approach looks fine to me. You will have to transfer the files/folders individually if you are using the base class library.
There may be 3rd party libraries available which will do this on one shot.

Where are the best locations to write an error log in Windows?

Where would you write an error log file, say ErrorLog.txt, in Windows? Keep in mind the path would need to be open to basic users for file write permissions.
I know the eventlog is a possible location for writing errors, but does it work for "user" level permissions?
EDIT: I am targeting Windows 2003, but I was posing the question in such a way as to have a "General Guideline" for where to write error logs.
As for the EventLog, I have had issues before in an ASP.NET application where I wanted to log to the Windows event log, but I had security issues causing me heartache. (I do not recall the issues I had, but remember having them.)
Have you considered logging the event viewer instead? If you want to write your own log, I suggest the users local app setting directory. Make a product directory under there. It's different on different version of Windows.
On Vista, you cannot put files like this under c:\program files. You will run into a lot of problems with it.
In .NET, you can find out this folder with this:
Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData)
And the Event Log is fairly simple to use too:
http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx
Text files are great for a server application (you did say Windows 2003). You should have a separate log file for each server application, the location is really a matter of convention to agree with administrators. E.g. for ASP.NET apps I've often seen them placed on a separate disk from the application under a folder structure that mimics the virtual directory structure.
For client apps, one disadvantage of text files is that a user may start multiple copies of your application (unless you've taken specific steps to prevent this). So you have the problem of contention if multiple instances attempt to write to the same log file. For this reason I would always prefer the Windows Event Log for client apps. One caveat is that you need to be an administrator to create an event log - this can be done e.g. by the setup package.
If you do use a file, I'd suggest using the folder Environment.SpecialFolder.LocalApplicationData rather than SpecialFolder.ApplicationData as suggested by others. LocalApplicationData is on the local disk: you don't want network problems to stop you from logging when the user has a roaming profile. For a WinForms application, use Application.LocalUserAppDataPath.
In either case, I would use a configuration file to decide where to log, so that you can easily change it. E.g. if you use Log4Net or a similar framework, you can easily configure whether to log to a text file, event log, both or elsewhere (e.g. a database) without changing your app.
The standard location(s) are:
C:\Documents and Settings\All Users\Application Data\MyApp
or
C:\Documents and Settings\%Username%\Application Data\MyApp
(aka %UserProfile%\Application Data\MyApp) which would match your user level permission requirement. It also separates logs created by different users.
Using .NET runtime, these can be built as:
AppDir=
System.Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData)
or
AppDir=
System.Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)
followed by:
MyAppDir = IO.Path.Combine(AppDir,'MyApp')
(Which, hopefully, maps Vista profiles too).
Personally, I would suggest using the Windows event log, it's great. If you can't, then write the file to the ApplicationData directory or the ProgramData (Application Data for all users on Windows XP) directory.
The Windows event log is definitely the way to go for logging of errors. You're not limited to the "Application" log as it's possible to create a new log target (e.g. "My Application"). That may need to be done as part of setup as I'm not sure if it requires administrative privileges or not. There's a Microsoft example in C# at http://support.microsoft.com/kb/307024.
Windows 2008 also has Event Log Forwarding which can be quite handy with server applications.
I agree with Lou on this, but I prefer to set this up in a configuration file like Joe said. You can use
file value="${APPDATA}/Test/log-file.txt"
("Test" could be whatever you want, or removed entirely) in the configuration file, which causes the log file to be written to "/Documents and Settings/LoginUser/Application
Data/Test" on Windows XP and to "/Users/LoginUser/AppData/Roaming/Test on Windows Vista.
I am just adding this as I just spent way too much time figuring how to make this work on Windows Vista...
This works as-is with Windows applications. To use logging in web applications, I found Phil Haack's blog entry on this to be a great resource:
http://haacked.com/archive/2005/03/07/ConfiguringLog4NetForWebApplications.aspx
%TEMP% is always a good location for logs I find.
Going against the grain here - it depends on what you need to do. Sometimes you need to manipulate the results, so log.txt is the way to go. It's simple, mutable, and easy to search.
Take an example from Joel. Fogbugz will send a log / dump of error messages via http to their server. You could do the same and not have to worry about the user's access rights on their drive.
I personally don't like to use the Windows Event Log where I am right now because we do not have access to the production servers, so that would mean that we would need to request access every time we wanted to look at the errors. It is not a speedy process unfortunately, so your troubleshooting is completely haulted by waiting for someone else. I also don't like that they kind of get lost within the ones from other applications. Sure you can sort, but it's just a bit of a nucance scrolling down. What you use will end up being a combination of personal preference coupled along with limitations of the enviroment you are working in. (log file, event log, or database)
Put it in the directory of the application. The users will need access to the folder to run and execute the application, and you can check write access on application startup.
The event log is a pain to use for troubleshooting, but you should still post significant errors there.
EDIT - You should look into the MS Application Blocks for logging if you are using .NET. They really make life easy.
Jeez Karma-killers. Next time I won't even offer a suggestion when the poster puts up an incomplete post.

Understanding IIS6 permissions, ACL, and identity--how can I restrict access?

When an ASP.NET application is running under IIS6.0 in Windows 2003 Server with impersonation, what user account is relevant for deciding file read/write/execute access privileges? I have two scenarios where I am trying to understand what access to grant/revoke. I thought the most relevant user is probably the identity specified in the Application Pool, but that doesn't seem to be the whole story.
The first issue concerns executing a local batch file via System.Diagnostics.Process.Start()--I can't do so when the AppPool is set to IWAM_WIN2K3WEB user, but it works fine if it is set to the Network Service identity. I of course made sure that the IWAM user has execute rights on the file.
The second involves writing to a file on the local hard drive--I'd like to be able to prevent doing so via the access control list via folder properties, but even when I set up all users in the folder as "read" (no users/groups with "write" at all), our ASP.NET still writes out the file no problem. How can it if it doesn't have write access?
Google search turns up bits and pieces but never the whole story.
what user account is relevant for [..] file read/write/execute access
As a rule: Always the user account the application/page runs under.
The IWAM account is pretty limited. I don't think it has permissions to start an external process. File access rights are irrelevant at this point.
If a user account (Network Service in your case) owns a file (i.e. has created it), it can do anything to this file, even if not explicitly allowed. Check who owns your file.
Process Monitor from Microsoft is a great tool to track down subtleties like this one.
A bit more searching reveals that the IWAM user isn't that well documented and we should stick with NETWORK SERVICE or a manually-supplied identity if we want to specify permissions for that user.