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How to use VirtFS Jailed Shell?

cPanel & WHM uses VirtFS to provide a jailed shell environment for users who connect to a server via SSH.

The jailed shell acts as a container for the user, and does not allow the user to access other users’ home directories on the server.

The virtfs directory

This directory contains configuration files, utilities, and BIND mounts.

• You cannot prevent the creation of this directory or disable it.
• This directory does not use any disk space. However, because it is a virtual mount point, some commands (for example, du) report that the directory uses disk space.
• BIND mounts create a virtual link between two locations on the file system.

Enable a jailed shell environment

WHM includes two options to activate a jailed shell environment.

The option that you use depends on the type of users for whom you wish to enable jailed shells.

To enable a jailed shell environment for all new and modified users, use the Use cPanel jailshell by default option in WHM’s Tweak Settings interface (WHM >> Home >> Server Configuration >> Tweak Settings).

• This option allows you to force the use of a jailed shell for new accounts and accounts that you subsequently edit in the following interfaces:
  • WHM’s Modify an Account interface (WHM >> Home >> Account Functions >> Modify An Account).
  • WHM’s Upgrade/Downgrade an Account interface (WHM >> Home >> Account Functions >> Upgrade/Downgrade An Account).
• Then, this option does not affect accounts that already exist on the server but that you have not edited in these interfaces.

To enable a jailed shell environment for a specific user, use WHM’s Manage Shell Access interface (WHM >> Home >> Account Functions >> Manage Shell Access).

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The following list of files have FAILED the md5sum comparison test. This means that the file has been changed in some way.
This could be a result of an OS update or application upgrade. If the change is unexpected it should be investigated:

/bin/crontab: FAILED
/bin/passwd: FAILED

Disable or remove a jailed shell environment

Remove a user’s jailed shell environment

To remove a jailed shell environment, perform the following steps:

1. Firstly, disable the jailed shell environment for the user in WHM’s Manage Shell Access interface.
2. Then, to unmount the VirtFS BIND mounts, run the following command, where username is the desired account username:

   umount /home/virtfs/username/usr/bin

The clear orphaned VirtFS mounts script

You can run the /usr/local/cpanel/scripts/clear_orphaned_virtfs_mounts script to unmount the BIND mounts for users who no longer exist or who no longer use a jailed shell environment.

This script removes the /home/virtfs/username/ directory and its contents.

To force the removal of all VirtFS mount points, run the following command, where username is an account’s username:

/usr/local/cpanel/scripts/clear_orphaned_virtfs_mounts --clearall

To check your system for VirtFS mount points, run the following command, where username is the desired account username:

grep -i username /proc/mounts