SBC's and ssh's encryptions
gheskett at shentel.net
Sun Nov 27 02:54:45 AEDT 2016
I have 2 questions today, but to put them in context, I'll describe the
I am in the process of cnc'ing an old Sheldon metal lathe. These can
make large amounts of flying metal chips & stringers when doing what
they do, so its paramount that the electronics to run them are either
far enough away, or put in a box thats well sealed, with fans in the box
to distribute the heat, and a fan blowing on the box to cool its
surface. So the motor supplies and motor drivers are in the box, and
supply their own fans, leaving room on the inside of the door for the
controlling interfaces and two SBC's:
A Raspberry pi 3b (4 core arm64 @ 1.2GHz, and a gig of ddr3 ram) to run
the program, called LinuxCNC.
And an odroid64-c2, faster 4 core arm64, 2GB of ram, which should handle
the graphical duties of controlling the program as it claims to be able
to drive a 4k display at 30 FPS.
I have tried running X on the raspi, but it hasn't enough memory or iron
to do it well. With only a gigabyte of ram and running from a u-sd card
for a boot drive, there is a hint of OOM to its failures.
Running htop on the odroid, its not x but sshd thats the bottleneck thats
causing the odroid to render at 3 or 4 frames per second at whatever the
default encryption was. Last night, I went around and converted all
my /etc/ssh/ssh_config's to:
cipher chacha20-poly1305 at openssh.com
This got me up to maybe 8 frames a second. My current networking test
setup has several devices, hubs and switches in the data path between
the SBC's but will only have about a 50 foot cable to a gigabit switch
in the final lashup from each SBC. There's another cnc'd machine there
that also needs net access to keep it up to date.
I am not too worried about being penetrated, a router running dd-wrt is
between me and the net modem, and has been for several years. No one has
come thru it except to my web page, on this machine. url in the sig.
So my two questions are:
Is there a faster thru-put yet encryption, like none?
How can I query the running ssh setup to see what encryption it is
Thank you, all.
Cheers, Gene Heskett
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
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