Corey Roth [MVP]

Sometimes, it is good to get back to the basics.  This may seem like a simple task for many of you, but there are many that don’t fully understand what is behind setting up a file share and the required permissions.  Years ago, I always thought I understood how this worked.  However, after taking some formal Windows Server training about 10 years ago, I discovered there was more to it than I thought. 

You probably already know how to get started when it comes to folder sharing.  You right click on the folder and go to properties.  You can also start by clicking on Share with.  When it comes to permissions of a file share, the ability of a user to access it depends on the combined permissions of two places.  The first is the Sharing tab.  This represents who can actually open the share when trying to connect to it over the network.  The second is the Security tab which represents the NTFS permissions on the underlying file system.  Think of this as being the same as the user being on that server locally and trying to open that folder and read / write files to it.  When a user attempts to read or write a file to the share over the network, the user’s permissions on both the Sharing and Security tab are combined and evaluated.  The most restrictive permission wins.  We’ll talk about that what that means more here in a bit.

Let’s set up a new file share.  Windows Server 2008 revamped some of these screens a bit, but they are pretty similar in previous versions of Windows.  Let’s start with the Security tab.  When you first start out, you’ll get a screen like this.

Your permissions may vary some on your system, but the above is pretty typical of what you will get on a new folder.  Note, that I have the Users group highlighted.  This is all Users of that particular domain.  By default, this group has the following permissions: Read & execute, List folder contents, and Read permissions.  What’s the difference between Read & execute compared to Read?  It’s the ability to launch executable files as the name implies.  Any time you want to grant a group of users the ability to read files in a folder, you will use these three permissions typically.  If you want to allow the user to write to files, you will want to grant the Write permission.  Lastly, if you want to grant permission to delete files also grant the Modify permission.  In all the above cases, you would be selecting the checkboxes in the Allow column.  Here is what your permissions might look like if you added a new group called Executives and they had Modify access.

Lastly, if you want the user or group to be able to do anything to the folder, grant them Full control access.  There are also even more granular permissions if you click the Advanced button but you typically will not need those.

Wondering about the Deny checkboxes?  These should only be used in extreme situations as they override all other permissions.  What this means is that if a user is a member of a group that has permission to the share but also is in another group with the Deny checkbox, then that user will not have that privilege.  I’m not a security expert, but I seem to remember there being a best practice stating that you want to avoid using Deny if at all possible.  Here is an example of where Everyone was granted access to the folder but the user Joy Williams is denied on all permissions.  That means that Joy will not be able to access the files in this share.

Keep in mind that in SharePoint, the Search indexer respects these permissions and results will be security trimmed based on the NTFS permissions.  Therefore if I index this share, Joy will not see search results from it.  For more information on setting up SharePoint to index file shares, see this post.

At this point, we’ve covered what you need to do to set permissions on the underlying file system using the Security tab.  Any user logged directly onto the server can open this folder and verify that they can read / write files based on the permissions you set.  This is a good way to test when users report issues accessing the file share since it eliminates any permissions issues caused by what you have set on the Sharing tab.

To make the folder visible on the network, you now need to go to the Sharing tab.

Click the Share button and you will be able to select with whom you want to share the folder.  Yours will probably have similar groups and users depending on who originally created the folder.

In the drop down list, you can select Everyone or browse for specific people and groups.  In this case, I am going to add Everyone and our Executives group.

I granted Everyone Read access and Executives have Read / Write access.  When I click Share the file will now be shared using the same name as the folder (by default).

This gives you the path to the file share.  In my case, it’s \\sp2010\MyFileShare.  If you don’t like the name it chose, you can click on the Advanced Sharing button which gives you some more options.  At this point, your share is ready to go using the path you see.  With my Share, members of the Executives group will be able to modify files and everyone else will just be able to read them.

Now what happens if the permissions between the Sharing tab and the Security tab don’t match?  For example, the user has Read permission on the Sharing tab and Write permission on the Security tab.  If you remember from earlier, I said that the most restrictive permission applies.  Let’s take a look at a few examples in the table below.

Hopefully this table clears things up as far as permissions go.  Now what if your users get an error trying to use the file share?  First determine where the error occurs.  Can the user actually open the file share folder?  If not, they will probably get an Access is Denied error.  This tells you that the issue lies in the Sharing tab.  If they can open the file share folder, but can’t open a file or perhaps write to it, then you know you have an issue with what is on the Security tab.

This may seem pretty basic to some of you, but I think it will serve as a handy reference to people that have never set up a file share before.