creating symbolic link: Protocol error

Question

I have created linux (Centos) on my virtual box. When I ssh to it and I try to create symbolic link (on my shared folder with full access):

ln -s path/folder/example myFolder

I get error:

ln: creating symbolic link `myFolder': Protocol error

Is there any reason or solution to this?

Were you able to resolve this issue? I am also seeing similar issue `root@57856515e02b:/artifacts/test/install/lib# ln -s /usr/share/tcltk/tcl8.5 /artifacts/test/install/lib/ ln: failed to create symbolic link '/artifacts/test/install/lib/tcl8.5': Protocol error` — , Apr 25 '17 at 07:43
For me, running as admin wasn't enough, but here was my answer: https://stackoverflow.com/a/60741351/470749 — Ryan, Mar 18 '20 at 14:14

score 35 · Answer 1 · answered Oct 24 '13 at 19:37

35

Right click on your command prompt and "Run as Administrator" (or whatever program you're using to make those symlinks needs to be run as adminstrator).

answered Oct 24 '13 at 19:37

Angela Zenner

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Actually, protocol errors in creating symlinks are common to virtual boxes running on windows. Running the shell as an admin generally corrects the issue. – baaj Jun 01 '15 at 22:32
I had a similar issue but when you run the VM as administrator you'll be able to create symbolic links. For more information also have a look at: http://stackoverflow.com/a/28674584/1494559 – np20 Apr 01 '16 at 09:07
1

Can you explain what you need to do to "Right click"? Is that a particular escape sequence in the SSH session? – Toby Speight Apr 26 '17 at 06:55
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@TobySpeight they mean right-click the icon/shortcut/whatever in Windows that launches the command prompt. – alexw Jul 05 '17 at 16:13
@alexw, what does Windows have to do with any of this? – Toby Speight Jul 05 '17 at 16:21
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OP says that their host OS is windows 7. – alexw Jul 05 '17 at 18:41
This should have been the accepted solution. However the host is launching the VM, it has to done as _an administrator_ – sandman Nov 21 '18 at 23:00
Im having this problem in windows 10, running the cmd as admin tried halting and much more – ii iml0sto1 Jun 23 '21 at 12:32

score 30 · Answer 2 · edited May 23 '17 at 12:26

Here is the solution in a ticket on virtualbox.org : https://www.virtualbox.org/ticket/10085#comment:32 (Note: Execute "whoami /priv" in console with Administrative privileges)

I have done some Windows research on this bug.

If your user is of the Administrator type (rather than a Standard account), there's no way to run VB with symlinks working without the UAC prompt.

If you have a Standard user account (or if you are willing to switch your account to Standard and create a separate Admin account), the solution exists. You will, however, need admin privileges to accomplish several of the steps (not necesarrily for your user account).
Run the Local Security Policy (Win+R, type "secpol.msc", confirm UAC). Then navigate to "Local Policies->User Rights Assignment".
Find the permission called "Create symbolic links" and double-click it. Add your user to the list of objects having this permission. Or you can add the "Users" group. Log off and log on. You can check the success by running in console:
whoami /priv
If you see the privilege SeCreateSymbolicLinkPrivilege enabled, you've done well.
Make sure your user has proper access to the shared folder on host system.
As mentioned here earlier, execute
VBoxManage setextradata VM_NAME VBoxInternal2/SharedFoldersEnableSymlinksCreate/SHARE_NAME 1
in a console from the C:\Program Files\VirtualBox folder. Don't forget to substitute VM_NAME with the name of your VM and SHARE_NAME with the name of the shared folder (as it appears in the VM settings).
You're done.
If you happen to own one of the "lesser" version of windows (e.g. 7 Home), you don't have the "secpol.msc" utility. See How do I grant SeCreateSymbolicLink on Windows Vista Home edition for help.

Thanks, use secpol.msc and gave myself privs. Worked perfectly. — partyd, Jul 29 '17 at 01:47
It works, thanks! Small note though: if whoami /priv lists your privilege as "Disabled" - don't worry, it just means something else (https://social.technet.microsoft.com/Forums/ie/en-US/e24a35b3-fb72-4918-8e51-562e2ad8d8f5/what-is-the-state-column-returned-by-whoami-priv?forum=winserversecurity) . If it is listed, it works for your user. — tporeba, Apr 03 '18 at 11:25
Thank you. This helped me to solve my symlinking problem in the Drupal VM. — drupalfan, Dec 18 '21 at 17:16

score 26 · Accepted Answer · answered Jul 27 '13 at 07:20

26

It's a problem with the host filesystem. Check the permissions on the host folder are adequate and the the host filesystem supports symlinks.

answered Jul 27 '13 at 07:20

Paul Dixon

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The host system is windows 7. Is there any solution to enable it? – TroodoN-Mike Jul 27 '13 at 07:29
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Bad solution for this is to create symlinks in windows 7 by using mklink. Example: mklink /D myFolder path/folder/example – TroodoN-Mike Jul 27 '13 at 07:59
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from which API/layer does the `Protocol error` message come from here? – n611x007 Apr 16 '15 at 13:28
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whatever app you used to launch your VM, VBox, or vagrant or ... you have to run the app _as an administrator_ – sandman Nov 21 '18 at 22:57

cancerbero · Answer 4 · 2017-09-10T03:49:26.573

As I understand, Windows VirtualBox hosts doesn't support links (from https://www.virtualbox.org/manual/ch04.html#sharedfolders)

Starting with version 4.0, VirtualBox shared folders also support symbolic links (symlinks), under the following conditions:

The host operating system must support symlinks (i.e. a Mac, Linux or Solaris host is required).

Currently only Linux and Solaris Guest Additions support symlinks.

For security reasons the guest OS is not allowed to create symlinks by default. If you trust the guest OS to not abuse the functionality, you can enable creation of symlinks for "sharename" with:

VBoxManage setextradata "VM name" VBoxInternal2/SharedFoldersEnableSymlinksCreate/sharename 1

Ukr · Answer 5 · 2019-11-10T23:42:27.203

By default VirtualBox VM disables creation of symbolic links.

Oracle VM VirtualBox shared folders support symbolic links under the following conditions:

The host operating system must support symlinks. For example, a Mac OS X, Linux, or Oracle Solaris host is required.
Currently only Linux and Oracle Solaris Guest Additions support symlinks.
For security reasons the guest OS is not allowed to create symlinks by default.

To enable creation of symlinks for a shared folder you should do:

Run this command on your host (where {VM_name} is the name of VM and {share_folder_name} is the name of shared directory):

$ VBoxManage setextradata "{VM_name}" VBoxInternal2/SharedFoldersEnableSymlinksCreate/{share_folder_name} 1

In my case it looks like:

$ VBoxManage setextradata "ubuntu16" VBoxInternal2/SharedFoldersEnableSymlinksCreate/shared 1

Reboot the VM.

More information you can find here:

https://docs.oracle.com/cd/E97728_01/E97727/html/sharedfolders.html https://www.virtualbox.org/ticket/18572?cversion=0&cnum_hist=2

score 1 · Answer 6 · answered Aug 18 '22 at 05:32

I solved this issue by changing the local security policy in my windows. Search for local security policy and open it then on the left-hand side select Local Policies -> User Rights Assignments -> Create Symbolic Links

Click on Add User or Group
Type in everyone in the select user/group prompt.
Reboot your system

It should work.

score 0 · Answer 7 · answered Dec 20 '16 at 09:26

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find the cmd.exe file. Right click on the cmd.exe . Select "Run as Administrator" menu option. It should work perfectly.

answered Dec 20 '16 at 09:26

Tanuj Jain

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You seem confused; why would you expect a CentOS box to have a `cmd.exe`, and how do you expect "Right click" to be performed in an SSH session? – Toby Speight Apr 26 '17 at 06:53
This answer is referring to the host OS. You missed the part where OP stated they are on Windows. – AaronHS Dec 20 '19 at 05:48

score 0 · Answer 8 · answered May 20 '20 at 01:39

Basically you need to again tell VirtualBox to enable symlinks. Here's the complete solution

Have this in your vagrant file,

config.vm.provider "virtualbox" do |v|
    v.customize ["setextradata", :id, "VBoxInternal2/SharedFoldersEnableSymlinksCreate/Folder_Name", "1"]
end

I recommended comment out any sync folder and let default ./(at host) synced at /vagrant(at guest). This will make sure your shared folder(Folder_Name) name is always vagrant as mentioned here https://www.vagrantup.com/docs/synced-folders/. Also, you won't face issues with ssh

If the symlink protocol error returns after restart or still persists run

VBoxManage setextradata "VM_Name" VBoxInternal2/SharedFoldersEnableSymlinksCreate/Folder_Name 1

vagrant halt
vagrant up

vagrant ssh

Usually, VBoxManagee is located at C:\Program Files\Oracle\VirtualBox\

Verify working of symlink by going to /vagrant and running

touch test.txt && ln -s test.txt test1.txt

PS: I have tried this on Windows Home which has limited accessibility to security settings

score 0 · Answer 9 · answered Feb 02 '22 at 10:22

0

I observed the same error in virtual box ( Lubuntu running in Windows 10). Issue got resolved by running "Oracle VM Virtualbox" using 'Run As Administrator' option.

answered Feb 02 '22 at 10:22

Jerin

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creating symbolic link: Protocol error

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