Cannot remove Unknown User

I had the same problem and followed your instructions (and those from concretenz) and it worked perfectly. Thanks guys!!

Thank you for your solution to removing the Unknown user in Screen Sharing System Preferences.

It worked perfectly.

I would like to add for others following this discussion that one does not need OS X server or the Server Admin Tools in order to access Workgroup Manager. Just download Workgroup Manager 10.8 from Apple Support.

Here are some more detailed instructions for using Workgroup Manager for those not familar with this tool which is not included in Mountain Lion OS X.

Install Workgroup Manager.

To have Workgroup Manager work independently of Server or a network connection do the following:

On the signin screen enter the IP address: of the machine you are working on.

Then enter the username and password of the machine.

Workgroup Manager will then work in standalone mode with your Mountain Lion OS X.

In the Workgroup Manager file menu navigate to View and turn on Show System Records

then select Accounts in the top icon bar menu

then in the tab bar below on the left select the icon with three people which will show below it group name.

In the list below on the left select Screen Sharing ACL (GID 401).

Then in the large box on the right select the members tab and you will see the unknown user(s) listed.

Select the unknown user(s) to be deleted and hit the minus ➖ button on the right.

Then hit the Save button below.

Exit Workgroup Manager and you will find your unknown user(s) will no longer appear in System Preferences Sharing.

Where do you type in the 'sudo dscl' code? I have no clue how to get there. 😟

Mille grazie, Andrea! Spero che l'Italiano è giusto.

Workgroup Manager also worked for me. However, after saving, I also had to reboot in order for the unknown user to be removed...

Thanks.

I also used WGM after finding out about it. 😉

Directory Utility is on your Mac already and can do this:

From the Finder use the "Go" menu and click "Go to Folder..." or use Command + Shift + G

Paste this in:

/System/Library/CoreServices/Directory Utility.app

 FIrst Find the Users you still use:

On the left sidebar you can find your users and their GeneratedUID is the field you are looking for on the right when you click on each user.

 Copy/Paste the UIDs of each user you use to a Stickie or somewhere you can paste text for a moment.

We want to note them so we don't delete the wrong one, although I am not sure that would really hurt anything. You could probably just go back in manually and add what you want.

 Finding the groups:

Up near the top toolbar you will see a couple drop down menus completing a sentence that says "Viewing <Users> in node </Local/Default>",

 Change "Users" to groups, click the lock and authenticate as an admin user.

Choose either "Remote Login ACL" or "Screen Sharing ACL" from the left and delete out the entries you didn't save before in the copy/paste. Don't forget to change both the "GroupMembers" and the "GroupMemebership".

 Click "Save" and you are done!

(If anyone really wants the command line way to work, try com.apple.access_screensharing instead of com.apple.access_ssh, although I really recommend some sort of GUI for this unless you are familiar with such things and were just looking for the right file.

Edit: Oh and check "SharePoints" instead of "Groups" if you are having this issue on a shared folder. The folder will list the groupID but also the groupName, which may be the folder name, on mine it was not but likely because of a rename or copy. Then swicth back to Groups and find the group, repeat the steps from clicking the lock and on.

Looks like the Unknown User should be assigned a UID of FFFFEEEE-DDDD-CCCC-BBBB-AAAA0000000063 but I have seen it keep the old UID of the user before.

Doesn't work for me. The delete icon is greyed out and thus I can't select it to delete the unknown user. Help!

I am with you until I try to delete. The list of members is completely greyed out so I can't select any of them to delete. How do I make them selectable?

In addition, the "unknown user" that shows up in Screen Sharing under System Preferences is NOT one of the members of the Screen Sharing ACL in WGM. Very strange! I have a member called "Not Found" with ID 47200640-. Anyone know what that is?

Again, I'm with you on all the steps. But when I get to the Members list for Screen Sharing ACL, I don't see "unknown user" there, I see "Not Found" instead (even though I have unknown user in Screen Sharing in System Preferences. Moreover, even if it were there, I couldn't delete it because all the Members are greyed out. So I can't select them to delete one. Ideas? Thx

Any kind of lock icon or anything? Are you an Admin? Usually with things like this you need to be an Admin and/or click a lock to be able to make changes. There is a few different "Unknown Users" that I have found. You should be fine removing it but never a bad idea to back up first. If you still have problems with that app try my instructions on the bottom of this page.

Hi

i had the same problemes with unknown user and i would like to know it that means someone using my computer?

Please,can you re explain to me how to do it as im not a geek on computing.

I'll but i was too scared to delete something that i shouldn't delete.

how could i know which one is the unknown user

I have some decent instructions at the bottom here that can maybe help you accomplish your task. It doesn't mean that someone has access to your computer, to set your mind at ease about that. The unknown user occurs because the user existed at one time and was removed leaving a blank entry in the database with no name. If you still have troubles after following my instructions at the bottom, let me know and we will try and find a creative way for you to get hands on help.