Turn off encryption from client to server?

[Philipp Hanselmann]

Todd O'Bryan schrieb:
> Thanks to Scott Balneaves and Jim Kronebusch. Jim responded directly 
> to me, probably bitten by the fact that the Reply button doesn't reply 
> to the list. (Can I tell you how many times I've sent things to 
> individuals, rather than a list, because of lists that make this 
> choice...) I've included his answer below:
>
> On Fri, 03 Aug 2007 15:56:48 -0400, Todd O'Bryan wrote
>> Hey all!
>>
>> School starts next week for me and I'm wondering if there's an easy way
>> to turn off the SSH encryption between the thin clients and the server.
>> The whole lab is on a self-contained network behind the server and I
>> just don't need the security. I'm hoping that not making the clients do
>> the extra bit of work to decrypt the video from the server will speed
>> things up a little. The lab works wonderfully, but, especially with
>> video or animation (I teach programming.), a little extra speed would be
>> a nice thing indeed.
>>
>> TAO
>
> Download the new ldm from:
>
> http://codebrowse.launchpad.net/~gideon/ltsp/gadi-ldm-mods-ltsp/download/gadi%40ltsp.org-20070521205254-ek710bofdpdtlwlz/x_Matt_Zimmerman_%3Cmatt.zimmerman%40canonical.com%3E_Tue_Jun__7_19%3A59%3A49_2005_32192.0/ldm 
>
>
> Then replace the current /opt/ltsp/i386/usr/sbin/ldm with the new one 
> (make a backup
> copy just in case).  Then modify your /opt/ltsp/i386/etc/lts.conf and 
> add the following:
>
> LDM_DIRECTX=True
>
> Reboot your clients and you're ready to rock.
>
I tried that (LDM_DIRECTX=True), but I am not sure if is really working 
under Feisty:

On a thin client I noticed that ssh is still running with encryption!

# ps aux | grep ssh
ssh -v -c blowfish-cbc,aes128-cbc,3des-cbc -M -S /tmp/.ltspfs-socket user11 at 192.168.0.254 /bin/bash --login -c ' env  LTSP_CLIENT="demo" PULSE_SERVER=tcp:192.168.0.244:4713 ESPEAKER=192.168.0.244:16001 DISPLAY=192.168.0.244:6 /etc/X11/Xsession && ltspfsmounter all cleanup ' ; kill -1 $PPID


Independently, to bypass the encryption, I tried to active XDMCP like this:

1.) active xdmcp in /etc/gdm/gdm-cdd.conf, with Enable=True (section 
[xdmcp])
2.) add this line to /opt/ltsp/i386/etc/lts.conf SCREEN_01 = startx

With this I got  login screens from the gdm display manager on all 10 
thin clients. Unfortunately I noticed that with this steps the keyboards 
and mouses on all thin clients not reacting!

SchoolNet has about 300 customers with a thin client solutions provided 
from us. All this costumers have between 5 to 20 clients (400 MHz, 96- 
128 MB) connected on a server (Pentium 4, 3GHz, 2 - 4 Gbyte). The 
testing which we have done up to know with Edubuntu Feisty, shows that 
with our actual hardware (Pentium 4,3GHz, 2 - 4 Gbyte) , Edubuntu Feisty 
can't support not more than 10 thin clients.
I assume we can reach again 20 thin clients, if the encryption is 
switched off! Like our server is protected by a firewall (Shorewall) we 
don't need the encryption!

In our actual solution (getopenlab) we using a KDE desktop, so I think 
Gnome should have a slightly better performance! I hope I am note forced 
to implement a other light weight desktop, like XFCE for example.

Philipp



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Philipp Hanselmann
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