Spread of open software and applicationsUsing laboratories that employ free software (operating systems and applications) aligns schools to the principles of independence and neutrality of taught technologies. Such framework allows the maximumfreedom use the technology and to deepen student’s knowledge about it. Both when studying, and on the job track, students and teachers will be able to use the same software at their own house.Creation of a community among teachersSpecifically among the teachers responsible for the laboratories, that have the exact identical software available. With the collaboration of these people, other teachers can be involved too: both challenges and didactic opportunities are often common ground.DocumentationLTSP- using two network interface controller (NIC)OpenScuola laboratories use a LTSP server (teacher’s terminal) and thin clients (students’ terminals). The bottleneck is often the connection speed between the server and the switch connected to the clients,due to the high bandwidth requirements form non-compressed video streaming from server to clients.

Using two NICs on the server can allow us to double the bandwidth both in upload and download.

An LTSP client will use as server the one from which it received the boot PXE image.
To be sure that the connection is shared equally between the two NICs it is thus convenient to have twoseparated ethernet an Ip networks (in this way, DHCP requests cannot reach the wrong NIC).

In the following examples, we will use two NICs, enp1s0 e enp2s0 with the addresses

enp1s0 10.100.10.10/24
enp2s0 10.100.11.10/24

We want to connect 10 clients to each of these NICs, with addresses .21 -> .30.

To configure DHCP server dnsmasq in order two have two different pools of addresses depending on which NIC receives the request, modify the line containing dhcp-range=… in the configuration file /etc/dnsmasq.d/ltsp-server-dnsmasq.conf as follows:

original:

dhcp-range=10.100.10.21,10.100.10.30,8h

after modification

dhcp-range=enp1s0,10.100.10.21,10.100.10.30,8h
dhcp-range=enp2s0,10.100.11.21,10.100.11.30,8h

At this point, restart dnsmasq daemon:

# systemctl restart dnsmasq

This will allow clients to boot via PXE, but PCs on the second NIC will not be able to authenticate on the LTSP server and proceed with chroot. To allow that, edit the configuration file of LTSP lts.conf (solitamente in /var/lib/tftpboot/ltsp/i386/lts.conf) and add the following rows:

[10.100.11.21]
LDM_USERNAME=cooluser1121
LDM_PASSWORD=mypassword1121

[10.100.11.22]
LDM_USERNAME=cooluser1122
LDM_PASSWORD=mypassword1122

[10.100.11.23]
LDM_USERNAME=cooluser1123
LDM_PASSWORD=mypassword1123
 .
 .
 .
[10.100.11.30]
LDM_USERNAME=cooluser1130
LDM_PASSWORD=mypassword1130

Users cooluser11xx must be connected to the system to allow thin clients on the additional network to boot.

Notice that using this method is possible to reach more than two networks in the lab, “lead” by the same LTSP server: in this way it is possible to have a single high-performance LTSP server to which many low-cost thin clients are connected.