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Date:      Wed, 10 Apr 2002 03:09:18 -0700
From:      Benjamin Krueger <benjamin@macguire.net>
To:        Patrick Thomas <root@utility.clubscholarship.com>
Cc:        dnelson@allantgroup.com, freebsd-questions@freebsd.org
Subject:   Re: overhead: sshd x 5 or screen ?
Message-ID:  <20020410030918.B4277@rain.macguire.net>
In-Reply-To: <20020410005847.A4277@rain.macguire.net>; from benjamin@macguire.net on Wed, Apr 10, 2002 at 12:58:47AM -0700
References:  <20020409151352.R59130-100000@utility.clubscholarship.com> <20020409225208.GF84522@dan.emsphone.com> <20020410005847.A4277@rain.macguire.net>

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* Dan Nelson (dnelson@allantgroup.com) [020409 15:53]:
> In the last episode (Apr 09), Patrick Thomas said:
> > I am wondering what causes more overhead (disk, memory, and processor
> > utilization):
> > 
> > - running 5 concurrent ssh connections into a FreeBSD server
> > 
> > - running 1 ssh connection into a FreeBSD server, and using `screen` to
> > create 5 windows ?
> 
> 5 sshs, because any output from session is encrypted and sent over the
> wire, where with screen only output to the visisble window is sent.

I'm not sure I follow the logic you're using here. How does being encrypted
and sent over the wire reduce overhead? He did not mention whether this was a
concern for the client or server, but assumably its server.

I should say that all things being equal, a single ssh session with a single
screen session is going to cause less load on the server. 

Consider that each network connection uses additional resources. 5 
connections rather than 1. Each individual connection does utilize unique
resources. Consider also that you need to encrypt 5 unique sshd sessions, 
rather than 1. Using a shared library will help reduce the memory footprint, 
but not the cpu usage.

What you get are 4 extra network connections, and 4 extra sshd instances to 
replace 1 instance of screen. Somehow, I think screen is going to come out the 
winner. :)

-- 
Benjamin Krueger

"Life is far too important a thing ever to talk seriously about."
- Oscar Wilde (1854 - 1900)
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