SBC's and ssh's encryptions

Gene Heskett gheskett at
Sun Nov 27 02:54:45 AEDT 2016

Greetings everybody;

I have 2 questions today, but to put them in context, I'll describe the 
setup first.

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

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 
actually using?

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 <>

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