[clug] Diagnosing SSH performance problems [SEC=UNCLASSIFIED]

Craig Small csmall at enc.com.au
Thu Dec 10 05:33:16 MST 2009

On Thu, Dec 10, 2009 at 10:59:12PM +1100, Daniel Pittman wrote:
> Michael Cohen <scudette at gmail.com> writes:
> > What you describes sounds like your machine is configured for too high an
> > MTU for the link.
> Are you assuming a noisy link, such as an analog modem without error
> correction, or something like that?
Crummy wireless/WiFi links look something like that too; but then the
bulk transfer would suffer as well. To me a MTU problem would hurt bulk
transfers way more. You see MTU type problems where you can login fine
or type simple commands, but the moment you run top or ls -lR it locks

Could you turn on something temporary like tcp echo to see if it is the
interactive part that is causing the problems or ssh itself?

Is it a "clear" internet connection?  Some places, in some workplaces,
like to do evil things to all the packets that pass from inside to
outside.  You might find the web traffic passes ok because its handling
differently. Of course if this is from home then it doesn't apply.

 - Craig
Craig Small      GnuPG:1C1B D893 1418 2AF4 45EE  95CB C76C E5AC 12CA DFA5
http://www.enc.com.au/                             csmall at : enc.com.au
http://www.debian.org/          Debian GNU/Linux, software should be Free 

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