Connecting to file shares

Chapter 10 - Connecting to file shares

 

As we mentioned in Chapter 8, the Windows Command Prompt is based off the old DOS command line, and DOS had barely any networking commands. Starting with Windows for Workgroups, Windows focused heavily on networking, and also on file sharing. "File sharing" is one of the most basic functions of computer networking. It basically means making files available to other users and systems via a network connection. Shared folders are generally referred to as "file shares" or more simply as "shares." Microsoft has for years made it easy to share files from Windows (maybe too easy, given how quickly viruses spread over the Internet in the first years of the 21st century).

But do you need to use Windows's graphical tools to access file shares? Not at all! DOS might have lacked file-sharing commands, but the Windows Command Prompt includes them. Using these commands, you can connect and disconnect from shared folders, and even create your own shares. 

 

MAPPING NETWORK DRIVES

 

You might have heard people talk about "mapping a network drive." What does that phrase mean? "Mapping a network drive" refers to taking a shared network folder it and making it appear on your Windows system with a drive letter. When you plug in a USB flash drive or a USB hard drive, you're used to it appearing in the Computer window with the next available drive letter. By mapping a network drive, you can make it appear in Computer with a drive letter, just like any other external drive. You can then issue commands from the Command Prompt to move, delete, and copy files to and from the network share.

Assuming, of course, that you have the proper share permissions, which we shall discuss in the next section.

 

SHARE PERMISSIONS

 

We've already discussed NTFS permissions in Chapter 5. Share permissions, however, are something entirely different from NTFS permissions. NTFS generally deal with which users and groups can access a file. Share permissions control which users can access the shared folder or file, and what level of access they have to the folder, over a network connection. However, NTFS permissions can override share permissions. If you have the share permission to add files to a shared folder, but your account only possesses the NTFS Read permission, you will not be able to copy any files to the share.

This can seem confusing, but taken piece by piece, share permissions are straightforward. In fact, there are six major NTFS permissions, but only three share permissions: Read, Change, and Full.

The Read share permission gives a user permission to view the file or folder over the network. It works a lot like the Read NTFS permission. A user with the Read permission will be able to see the file in the directory, open up the file, and read it. However, the user will not be able to alter the file or delete it.

The Change share permission gives the user permission to alter a shared file. Basically, it functions like the NTFS Write permission. The user has permission to change a file with the Write permission, but he cannot delete the file, and he cannot change its share permissions. 

The Full share permission, like the NTFS Full Control permission, gives the user complete control over the file or folder. If you have the Full share permission, you can read the file, make changes to it, and delete it. You can also alter its share permissions for other users. 

What happens when the share permissions and NTFS permissions conflict? The rule of thumb is that the most restrictive permission wins. For instance, say you have the Full share permission to a file, but only the NTFS Read permission. You'll be able to read the file, but the NTFS permissions will block you from editing the file in anyway. Likewise, let's say you have the NTFS Full Control permission for a file, but only the Read share permission. You'll be able to read the file, but since your share permissions are limited to Read, you won't be able to do anything else with it. 

 

VIEWING FILE SHARES

 

The first step to connecting to file shares from the Command Prompt is to find those shared folders. To connect to a file server, you'll need to know either its IP address, or its Fully Qualified Domain Name. (A FQDN is a computer's proper DNS name - for instance, fileserver.testdomain.com.) Whether connecting via the IP address or the FQDN, you'll need to use a syntax called UNC - Uniform Naming Convention. UNC is a technology Microsoft uses in Windows to designate the location of a network resource. For example, if you have a file server at 192.168.1.1 which contains a shared folder named Data, the UNC path to the server and the folder would look like this:

\\192.168.1.1\data

You'll need to use UNC to designate the server and folder you want to use when working with file shares from the Command Prompt. Let's say you want to view the shared folders available on a server with the IP address of 192.168.1.1. To do so, you would use the NET command. The NET command is the Swiss army knife of the Command Prompt. It does a variety of different things, and is your chief tool for connecting to file shares from the command line. More specifically, you would use the NET VIEW command to view the available file shares on a server:

NET VIEW \\192.168.1.1

The command will generate an output that should look something like this:

Shared resources at \\192.168.1.1

Share name  Type   Used as  Comment

------------------------------------------------

images      Disk

data          Disk          

backup     Disk

The command completed successfully.

From this output, you can see that the server at \\192.168.1.1 has three separate shared folders available - images, data, and disk. You can then use this information to connect to the file share and map it as a network drive, which we'll discuss how to do in the next section.

 

CONNECTING TO A FILE SHARE

 

To connect to a file share, you again use the NET command. To connect, however, you'll use the NET USE command, rather than NET VIEW. If you wanted to connect to the data fileshare on \\192.168.1.1 and map it as your computer's H drive, you would use this command:

NET USE H: \\192.168.1.1\data

This will mount the shared folder "data" at \\192.168.1.1 as your computer's H drive.

Unfortunately, if you reboot your computer, or log out and then log back into your account, this will break your connection to the share, and you'll have to remap the network drive all over again. You can avoid this by using NET USE with the /PERSISTENT switch:

NET USE H: \\192.168.1.1\data /PERSISTENT:YES

This will tell Windows to remap the network drive every time you log into your account. If the network share is available when you log in, Windows will remap the drive for you.

You might also need to connect to the share as a different user. This can be accomplished via the /USER switch with the NET USE command. If you wanted to connect to the \\192.168.1.1\data share using the user account named camalas, you would use the NET USE command with these parameters:

NET USE H: \\192.168.1.1\data /USER:CAMALAS

This will connect you to the network share at \\192.168.1.1\data using camalas's user account.

 

DISCONNECTING FROM A FILE SHARE

 

If you no longer need a particular network drive, you might want to disconnect it. Just as with mapping a network drive, you can disconnect a network drive from the Command Prompt via the NET USE command. To disconnect the H drive we mapped in the earlier example, you would use this command:

NET USE H: \\192.168.1.1\data /DELETE

Using the /DELETE switch might seem rather drastic. Fortunately, the /DELETE switch is misnamed. It doesn't delete any of the files or subdirectories contained in the file share. It only disconnects the mapped network drive from your computer, and you can reconnect to it at your leisure.

 

CREATE A FILE SHARE

 

In addition to connecting to file shares from the Command Prompt, you can also create your own file shares using the command line. Windows Vista and Windows 7 are generally called "client systems", since they're designed to interact with larger server systems running a version of Windows Server. However, the client versions of Windows can act as limited server systems. You can created shared folders on your Windows client system, and allow users to connect to them remotely.

As with finding and connecting to network shares, you use the NET command to create file shares on your Windows computer. To create network shares, you use the NET SHARE version of the NET command. Let's say you have a directory named data in the root directory of your C drive you want to share. To make it into a shared folder, use this command:

NET SHARE DATA=C:\DATA

This will set C:\DATA as a shared folder with a share name of "DATA." The new share won't do you very much good unless you assign share permissions to users. You also use the NET SHARE command to assign share permissions to users. For instance, if you wanted to grant the camalas user account the Read permission to the DATA share:

NET SHARE DATA /GRANT:CAMALAS READ

This will assign the camalas user account the Read share permission. To assign the Change permission to the camalas user account, use this command:

NET SHARE DATA /GRANT:CAMALAS CHANGE

And to grant the Full share permission:

NET SHARE DATA /GRANT:CAMALAS FULL

Finally, to view all the file shares on your system, use the NET SHARE command without any arguments:

NET SHARE

This will generate a similar output to using NET VIEW to view the file shares on a remote system, but this listing will show only the file shares on the local system.