How to determine if the file sharing server is turned on?

Question

If I want to check the availability of the server, but I don’t know about its shared resources, I can enter its UNC name (or IP address) in the Windows Explorer window even without the resource sharing directory :

How can I use this programmatically in .NET to check if the server is on the network? I'm trying to

My.Computer.FileSystem.DirectoryExists(UNCPath) 

but this only works for UNC paths such as \\MY_SERVER\Users , it is not intended to be used with \\MY_SERVER .

I would like to avoid Ping and stick with the functionality that works when the file system is running , because some servers may disable ICMP_ECHO due to security concerns.

(If you want to post any code, feel free to choose VB or C #.)

Answer 1

Edit: I am notified that this may be a duplicate solution for Q / A mentioned elsewhere . The difference is that another question accepts an answer that actually did not work for me, and I have reason to believe that using WMI limits the approach in this scenario (this requires credentials, see below). In this answer, I give an approach that really works for me. But if you really think this is a duplicate, keep marking it for closing and I will delete the whole question as unnecessary.

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I continued to study and try, and finally I decided to use TCP port 139 , the same as that used by the file sharing mechanism . Consider the following source as a draft (and don't forget to handle exceptions, etc.), but finally, I can have a piece of code that seems to work for me:

 Public Shared Function IsFileShareServerOnline(PCName As String, Timeout as Integer) As Boolean Const Port As Integer = 139 'port for file sharing service Dim IsOnline As Boolean = False Dim IP As Net.IPAddress = Net.Dns.GetHostAddresses(PCName)(0) Dim Address As Net.IPAddress = Net.IPAddress.Parse(IP.ToString()) Dim Socket As Net.Sockets.TcpClient = New Net.Sockets.TcpClient(Address.AddressFamily) Dim Connect = Socket.BeginConnect(Address, Port, Nothing, Nothing) Dim WaitingResult = Connect.AsyncWaitHandle.WaitOne(Timeout, False) If (Connect.IsCompleted) Then If WaitingResult Then Socket.EndConnect(Connect) IsOnline = True End If End If Socket.Close() Return IsOnline End Function 

There is a problem in the code that, at the first start, the remote computer cannot be detected, even if it is available. After repeating it works. The problem resumes (one bad detection) whenever a connection is made after a longer time. I am not a TCP / IP expert to understand the reason, maybe I am using a too short timeout (1 sec). The workaround is to give at least 2 connection attempts.

Before trying this approach, I also implemented and tested WMI-based requests, but they did not work without preliminary authentication on the remote computer, which was pretty useless in my scenario.