As I understand it, the Local Apps settings are enabled by default in
Lubuntu 12.04. Once LTSP is also installed, that means that one can run
on the LTSP client hardware (instead of the LTSP server hardware) any
app that is installed in the LTSP chroot image. For instance, xterm can
be run on the client via "ltsp-localapps xterm" (ltsp-localapps being
the script command by which an app must be launched locally).
To run an additional app locally, just install it in the chroot and
update the image:
sudo chroot /opt/ltsp/i386
sudo apt-get install <app-of-your-choice>
sudo ltsp-update-image
HOWEVER, Internet apps will launch but not work at this point due to
Name Resolution failure. So the LTSP server has to be set up as a NAT
gateway.
As far as I know, the most relevant instruction for doing that is here:
https://help.ubuntu.com/community/UbuntuLTSP/ThinClientHowtoNAT/
But I have not gotten that working, so I want to summarize the steps of
that instruction here and insert comments about my own implementation.
I trust someone will spot the problem.
** Edit /etc/ltsp/dhcpd.conf (sudo gedit /etc/ltsp/dhcpd.conf) setting
the routers option to the ip address of the ltsp server on the ltsp
network. eg
option routers 192.168.0.254;
and restart the dhcp server
sudo /etc/init.d/dhcp3-server restart
ON 11.10 restart the dhcp server
sudo /etc/init.d/ish-dhcp-server restart
Test: Reboot the test PC on the thin client network and check if it sees
the new default gateway (on linux type ip route and look at the line
beginning "default"; on windows type "route print" into a command prompt
and look for default gateway).
[COMMENT: I understand that LTSP servers have variously been set up with
default 192.168.0.254 or 192.168.0.1, but that now people are pressing
for a uniform default of 192.168.0.1, which is the way mine is set up.
I found dhcpd.conf already had "option routers 192.168.0.1" enabled.
And my test PC did indeed show a default gateway of 192.168.0.1.]
** On the LTSP server edit /etc/sysctl.conf (sudo gedit
/etc/sysctl.conf) and either add this line or uncomment if it's already
there:
net.ipv4.ip_forward=1
which will take effect at next server reboot. To make the setting
effective immediately, now run the command
sudo sysctl -w net.ipv4.ip_forward=1
[COMMENT: I only had to un-comment the line.]
** Enable network address translation. By default the ltsp network
address/mask is 192.168.0.0/24. Remember to change the example to fit
your network setup. Use a command like:
sudo iptables --table nat --append POSTROUTING --jump MASQUERADE
--source 192.168.0.0/24
to enable NAT. To make this setting permanent run
sudo sh -c 'iptables-save > /etc/ltsp/nat'
and add the extra line up iptables-restore < /etc/ltsp/nat to the bottom
of the eth0 (or whichever is your LTSP interface) stanza of
/etc/network/interfaces so it looks something like
auto eth0
iface eth0 inet static
address 192.168.0.254
netmask 255.255.255.0
broadcast 192.168.0.255
network 192.168.0.0
up iptables-restore < /etc/ltsp/nat
This creates a script called /etc/ltsp/nat which restores the NAT next
time the eth0 network interface comes up. Test: ping the dns server on
the main network from the test PC.
[COMMENT: I used the first two commands as written. My network is the
default 192.168.0.0/24. And since my LTSP interface it eth1, I added
the following to interfaces:
auto eth1
iface eth1 inet static
address 192.168.0.1
netmask 255.255.255.0
broadcast 192.168.0.255
network 192.168.0.0
up iptables-restore < /etc/ltsp/nat
But I thought it of interest that neither eth0 nor eth1 was initially
configured via /etc/network/interfaces. Lubuntu seems to prefer
Preferences: Network Connections, a nice GUI, and that is what I used to
set up eth1 for LTSP. But here, I didn't know how to use Network
Connections to add "up iptables-restore < /etc/ltsp/nat." So I hoped
editing interfaces as instructed would do the job.]
** Again, edit /etc/ltsp/dhcpd.conf, as above, setting the dns option to
the ip address of the main network DNS server (listed in
/etc/resolv.conf on the LTSP server beside the word "nameserver"), e.g.
option domain-name-servers 192.168.1.1;
and again restart the dhcp server
sudo /etc/init.d/dhcp3-server restart
Test: Reboot the test PC again, to update its DNS server. Try pinging a
real world server from the test PC by name, eg
ping www.ubuntu.com
[COMMENT: /etc/resolv.conf showed 127.0.0.1 for the nameserver. Given
the instruction's example of 192.168.1.1, this address seems unexpected,
but I tried it and it did not work. I also tried 192.168.0.1. Also
192.168.1.1, the address of the router, which I would have taken to be a
good bet. I also set the router to 10.0.0.1/255.255.255.0 and tried
that for the dhcpd.conf domain-name-server. (See more on that below.)
Finally I tried the openDNS servers that are set up in the router:
208.67.222.222; 208.67.220.220. Most of my failures simply resulted in
Name Resolution failures when local app chromium-browser was trying to
find a site. But at this point, something in my configuration seems to
have disabled LTSP DHCP altogether -- the LTSP client does not boot.]
-----------------------------------
MORE GENERAL INFO: My DSL modem is an AT&T that uses a non-configurable
LAN-side address of 192.168.0.1/255.255.0.0.
Initially I had the router set to 10.0.0.1/255.255.255.0, and computers
on the main network can ping and open the configuration page for the
modem. I was concerned that this would conflict with the LTSP server at
192.168.0.1, but LTSP clients worked OK -- perhaps because of the
differing netmasks of 255.255.255.0 vs. 255.255.0.0??
I also tested setting the router at 192.168.1.1/255.255.0.0. In this
configuration computers on the main network cannot see the modem at
192.168.0.1.
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