Advanced administration

In this chapter advanced administration tasks are described.

User Customisations with GOsa²

Create Users in Year Groups

In this example we want to create users in year groups, with common home directories for each group (home0/2014, home0/2015, etc.) We want to create the users by csv import.

(as root on Tjener)

mkdir /skole/tjener/home0/2014

(as superuser in Gosa)

Main menu: goto 'Directory structure', click the 'Students' department. The 'Base' field should show '/Students'. From the drop box 'Actions' choose 'Create'/'Department'. Fill in values for Name (2014) and Description fields (students graduating in 2014), leave the Base field as is (should be '/Students'). Save it clicking 'Ok'. Now the new department (2014) should show up below /Students. Click it.

Choose 'Groups' from the main menu; 'Actions'/Create/Group. Enter group name (leave 'Base' as is, should be /Students/2014) and click the check box left of 'Samba group'. 'Ok' to save it.

Choose 'users' from the main menu. Change to 'Students' in the Base field. An Entry 'NewStudent' should show up, click it. This is the 'students' template, not a real user. As you'll have to create such a template (to be able to use csv import for your structure) based on this one, notice all entries showing up in the Generic, POSIX and Samba tabs, maybe take screenshots. Now change to /Students/2014 in the Base field; choose Create/Template and start to fill in your desired values, first the Generic tab (add your new 2014 group under Group Membership, too), then add POSIX and Samba account.

Choose your new template when doing csv import; testing it with a few users recommended.

Other User Customisations

Creating folders in the home directories of all users

With this script the administrator can create a folder in each user's home directory and set access permissions and ownership.

In the example shown below with group=teachers and permissions=2770 a user can hand in an assignment by saving the file to the folder "assignments" where teachers are given write access to be able to make comments.

 #!/bin/bash
 home_path="/skole/tjener/home0"
 shared_folder="assignments"
 permissions="2770"
 created_dir=0
 for home in $(ls $home_path); do
    if [ ! -d "$home_path/$home/$shared_folder" ]; then
        mkdir $home_path/$home/$shared_folder
        chmod $permissions $home_path/$home/$shared_folder
        #set the right owner and group
        #"username" = "group name" = "folder name"
        user=$home
        group=teachers
        chown $user:$group $home_path/$home/$shared_folder
        ((created_dir+=1))
    else
        echo -e "the folder $home_path/$home/$shared_folder already exists.\n"
    fi
 done
 echo "$created_dir folders have been created"

Easy access to USB drives and CDROMs/DVDs

When users insert a USB drive or a DVD / CDROM into a (diskless) workstation, a popup window appears asking what to do with it, just like in any other normal installation.

When users insert a USB drive or a DVD / CDROM into a thin client there is only a notify-window showing up for a few seconds. The media is automatically mounted and it is possible to access it browsing to the /media/$user folder. This is quite difficult for many non experienced users.

It is possible to have the default KDE "Plasma" file manager Dolphin showing up if KDE "Plasma" (or LDXE, if installed in parallel to KDE "Plasma") is in use as desktop environment. To configure this, simply execute /usr/share/debian-edu-config/ltspfs-mounter-kde enable on the terminal server. (When using GNOME, device icons will be placed on the desktop allowing easy access).

In addition the following script could be used to create the symlink "media" for all users in their home folder for easy access to USB drives, CDROM / DVD or whatever media is connected to the thin client. This might come in handy if users want to edit files directly on their plugged in media.

 #!/bin/bash
 home_path="/skole/tjener/home0"
 shared_folder="media"
 permissions="775"
 created_dir=0;
 for home in $(ls $home_path); do
    if [ ! -d "$home_path/$home/$shared_folder" ]; then
        ln -s /media/$home $home_path/$home/$shared_folder
        ((created_dir+=1))
    else
        echo -e "the folder $home_path/$home/$shared_folder already exists.\n"
    fi
 done
 echo "$created_dir folders has been created"

A warning about removable media on LTSP servers

/!\ Warning: When inserted into an LTSP server USB drives and other removable media cause popup messages on remote LTSP clients.

If remote users acknowledge the popup or use pmount from the console, they can even mount the removable devices and access the files.

This is being tracked as Debian Edu bug #1376.

Use a dedicated storage server

Take these steps to set up a dedicated storage server for user home directories and possibly other data.

Now users should be able to access the files on 'nas-server.intern' directly by just visiting the '/tjener/nas-server/storage/' directory using any application on any workstation, LTSP client or LTSP server.

Restrict ssh login access

There are several ways to restrict ssh login, some are listed here.

Setup without LTSP clients

If no LTSP clients are used a simple solution is to create a new group (say sshusers) and to add a line to the machine's /etc/ssh/sshd_config file. Only members of the sshusers group will then be allowed to ssh into the machine from everywhere.

Managing this case with GOsa is quite simple:

Setup with LTSP clients

The default LTSP client setup uses ssh connections to the LTSP server. So a different approach using PAM is needed.

+ : alice jane bob john : ALL
+ : ALL : 10.0.0.0/8 192.168.0.0/24 192.168.1.0/24
- : ALL : ALL
#

If only dedicated LTSP servers are used, the 10.0.0.0/8 network could be dropped to disable internal ssh login access. Note: someone pluging in his box into the dedicated LTSP client network(s) will gain ssh access to the LTSP server(s) as well.

A note for more complex setups

If LTSP clients were attached to the backbone network 10.0.0.0/8 (combi server or LTSP cluster setup) things would be even more complicated and maybe only a sophisticated DHCP setup (in LDAP) checking the vendor-class-identifier together with apropriate PAM configuration would allow to disable internal ssh login.