Develop Reference

Access to the path is denied in ASP.Net

I have an ASP.Net application running in IIS which creates a file in a specified location using CsvWriter. If I use the full UNC path I get error that Access to the path is denied, however if I use Drive letter it works fine. What is puzzling me is that it does work with UNC path in development environment.
This code which creates the file
using (var writer = new StreamWriter(fileName))
using (var csv = new CsvWriter(writer, CultureInfo.InvariantCulture))
{
csv.WriteField("Foo");
csv.WriteField("Bar");
csv.NextRecord();
}
Following advice various posts such as Access to the path is denied and IIS7 Permissions Overview - ApplicationPoolIdentity and MS Documentation: Application Pool Identities. I was initially convinced my problem was security related. This was supported by the fact that the application would run perfectly in development environment (IIS Express) which uses my user credentials but not under IIS which uses Application Pool Identity. I gave MyApplicationPoolIdentity full access to the specific directory to no avail.
However, I discovered that if I use the drive letter (C:\myDirectory\mySubDirectory\myFile.csv) as opposed to the UNC path (\\myServer\myDirectory\mySubDirectory\myFile.csv) in production the file is created perfectly. Even though I have the application working my concern is that I may have some configuration issue with IIS or my server which may bite me later. So my question is what would cause the create file/write to fail using UNC path and not using Drive letter?
I am using Windows Server 2016.
Thanks
Tony

I think it is caused by permission issues. First, did you get any related error messages? Or you can try the following methods：
1.you can use Process Monitor to see which account is being used to access the share and what permission are required.
2.Check to ensure the account that IIS is running under has needed rights to the troublesome UNC.

Requested registry allow access without security leaks

Right now i am using an web application with code to read from and write to the registry. While debugging in Visual studio everything went fine but on the online test server it didn't run. the error exception message i am getting is:
System.Security.SecurityException: Requested registry access is not
allowed.
This is the code i am using:
private RegistryKey GetWritableBaseRegistryKey(string extendedPath)
{
var path = "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall";
return RegistryKey.OpenBaseKey(RegistryHive.CurrentUser, RegistryView.Default).OpenSubKey($"{path}\\{extendedPath}", true);
}
The sollutions i found where:
Solution 1
you will not be able to set AppPoolIdentity to a specific group, but
you can
create a local user (compmgmt.msc)
add the user to the administrator group (compmgmt.msc)
Set the application pool to run under that user, under Advanced Settings.
Obviously you know this is a very bad idea from a security
perspective, and should never ever ever be performed on a forward
facing server.
source
Solution 2
Create a separate console application to run the service in admin
modus so you could access the registry. This solution was performance
heavy because you need to run 2 separate applications.
Solution 3
Use this code to allow access to the registry.
RegistryPermission perm1 = new RegistryPermission(RegistryPermissionAccess.AllAccess, "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall");
perm1.Demand();
Or this code
RegistrySecurity rs = new RegistrySecurity();
string currentUserStr = Environment.UserDomainName + "\\" + Environment.UserName;
RegistryAccessRule accessRule = new RegistryAccessRule(currentUserStr, RegistryRights.WriteKey | RegistryRights.ReadKey | RegistryRights.Delete | RegistryRights.FullControl, AccessControlType.Allow);
rs.AddAccessRule(accessRule);
But these didn't work on the server however while debugging in visual studio the code ran fine.

In order for the web application to access the registry it must have sufficient permission. Consequently Solution 1 is the only one likely to work. It describes setting the web sites application pool to a user in the local administrators group. Its misses the steps about actually setting your IIS web site to use the newly created App Pool, which is why it might not work for you.
The technical process of reading a restricted registry, especially the application Uninstall registry key, inside a web server is really unlikely to be useful to you. Of what possible use is allowing a web server to access the servers own Application uninstall list going to be ?
I suspect you intend to open that registry key on the client's PC (my speculation) which is not going to be possible.

Check if file from remote server exists

i have an application which requires access permission to a file on remote server.
My app is in Server A, and the file i want to access is in Server B. These 2 servers are in the same domain.
I created a virtual directory in Server A for the directory in Server B. The name of virtual directory is FolderFromServerB and its path is \ServerB\Folder. I use a user for auth, and when i test the connection in IIS it says all is OK.
Also, when i put an anchor tag in a test file like below, i can access the file and the content is shown in the page:
Test file --> **This works**
But my problem is when i use code in order to if that file exists or not, it always returns with False. My code is like below:
FileInfo fi = new FileInfo(#"\FolderFromServerB/test.txt"); --> This doesn't work
Response.Write(fi.Exists); --> This always 'False'
I granted 'Full Control' permission to my user& NETWORK SERVICE & Everyone & Administratos in Server B but i didnt work neither.
How can i make it work?
It was working last week. I guess the server updated itself and some updates made that occur, but i couldn't find any workaround. Im so desperate now and i have to change all of my code and spend much time to make it work.

I found the workaround that is in web.config :
<identity impersonate="true" userName="{domain}\{username}" password="{password}"/>
I used File.Exist() for a few months, but then suddenly it was gone and didnt work, and i dont know why. But it is the solution above.

Your code does not work because the current execution folder of an ASP.Net application is not the folder of you application, but c:\windows\system32.
When you create the FileInfo object, you will try to read c:\windows\system32\FolderFromServerB\test.txt.
The <a href="FolderFromServerB/test.txt"> works because the link will be relative to the current page (it won't works if the page is in another directory).
If the file you are looking for is under your application directory, you can convert a virtual to a physical path using :
string actualFilePath = HttpContext.Current.Server.MapPath("~/FolderFromServerB/test.txt");
FileInfo fi = new FileInfo(actualFilePath);

Directory.exists returns false for mapped drive in c# coding

I am using Directory.Exists() in my windows service (that is programmed in C#, 3.5 framework)to check to see whether a particular directory exists in the drive. When I run in local machine it works fine, meaning I am able to access the directory.
But when I deploy the windows service on a Virtual Machine, and start the service, it is not able to find the directory even though the directory exists. The directory is mapped on as
Q: drive, Q:\\temp\\local\\ folder
But the windows services always returns false for the Directory.Exists().
However when I give C:\ drive in place of Q:\ it works, but does not work for a mapped drive. I have tried with the UNC path, and I have made sure the mapped drive have the administrative rights and infact the read, write and execute permission. But it still returns false.
Can anyone please tell me why? And how to resolve?

Make sure the drive is mapped under the same user as the Service is running. If you map the drive as user A, it is not automatically mapped for anyone else too.

Mapped drives are only restored during interactive login which services generally do not perform:
Map a network drive to be used by a service
Short version: You can't do it, use the full UNC path instead.

This is most probably a problem with privileges. Your Windows service is probably running under an account which doesn´t have enough privileges to access the network path.
This is a possible duplicate: Accessing mapped folder from a Windows Service written in C#
Another possible solution is to use impersonation, check it out:
http://msdn.microsoft.com/en-us/library/w070t6ka(v=vs.90).aspx
UPDATE
Came to think of it;
Try changing the identity of the application pool to a user with the same rights as your user.

As #Sriram pointed out the Directory.Exists() method will fail if any error occurs. What sort of exception do you get if you try to access the path?
Eg (for both mapped and UNC in case there is something going on there):
DirectoryInfo diMapped = new DirectoryInfo(#"Q:\temp\local\folder");
DirectoryInfo diUNC = new DirectoryInfo(#"\\servername\fnsw\tmp\126");
Note: Assuming that the white space before 'folder' in your path is a typo?

Steps to troubleshoot
Try accessing the network path manually in "Run" [WindowKey + R]
Try to access your map drive i.e.: M:\
Make sure you are the account owner of the mapping (mapping should be done under your account)
Go to Property and see if "Run As Administrator" is unchecked.
Remove mapping and re-add the mapping.
Make sure available offline (or sync offline) is turned off and folder is available from another computer.
Hope this helps!

Reading UNC path with FileSystemWatcher [duplicate]

I am trying to run a file watcher over some server path using windows service.
I am using my windows login credential to run the service, and am able to access this "someServerPath" from my login.
But when I do that from the FileSystemWatcher it throws:
The directory name \someServerPath is invalid" exception.
var fileWatcher = new FileSystemWatcher(GetServerPath())
{
NotifyFilter=(NotifyFilters.LastWrite|NotifyFilters.FileName),
EnableRaisingEvents=true,
IncludeSubdirectories=true
};
public static string GetServerPath()
{
return string.Format(#"\\{0}", FileServer1);
}
Can anyone please help me with this?

I have projects using the FileSystemWatcher object monitoring UNC paths without any issues.
My guess from looking at your code example may be that you are pointing the watcher at the root share of the server (//servername/) which may not be a valid file system share? I know it returns things like printers, scheduled tasks, etc. in windows explorer.
Try pointing the watcher to a share beneath the root - something like //servername/c$/ would be a good test example if you have remote administrative rights on the server.

With regards to the updated question, I agree that you probably need to specify a valid share, rather than just the remote server name.
[Update] Fixed previous question about the exception with this:
specify the name as #"\\someServerPath"
The \ is being escaped as a single \
When you prefix the string with an # symbol, it doesn't process the escape sequences.

I was just asked this question in regards to FileSystemWatcher code running as a service and the issue is permissions. I searched and found this question and answer but unfortunately none of the answers here solved the problem. Anyway, I just solved it, so I thought I would throw in the solution here for next guy who searches and find this question.
The drive was mapped as a logged in user but the service was running as LocalSystem. LocalSystem is a different account and does not have access to drives mapped by a user.
The fix is to either:
Authenticate first (I use a C# Class to establish a network connection with credentials)
Run your service as a user that has access to the share.
You can test LocalSystem authentication by using a LocalSystem command prompt, see How to open a command prompt running as Local System?

Even though this is already answered I thought I would put in my two cents worth becaus eyou can see this same error even if you supply valid paths.
You will get the same error when the process running the watcher does not have access to the remote share. This will happen if the watcher is in a service running under the System account and the share is created by a user. System does not have access to that share and wont recognize it, you will need to impersonate the user to get access to it.

although you can use a FileWatcher over the network, you will have to account for other factors, like disconnection of the network share. If your connection to the share is terminated (maintenance, lag, equipment reset, etc) you will no longer have a valid handle on the share in your filewatcher

You can't use directory watches over network shares, this is a limitation of the OS, not of .NET.