Re: 2 SSH questions: why does it pause so much, and, can I keep connection alive?

From: Darren Tucker (
Date: 03/31/04

Date: Wed, 31 Mar 2004 02:18:18 +0000 (UTC)

In article <>,
Michael Levin <> wrote:
>I'm running SSH clients on a Mac OSX to connect to a Unix box. Does anyone
>have any thoughts on the following:
>1) it works ok to connect, but every 30 seconds or so, everything freezes,
>and I have to wait a while (another 30 seconds). In the meantime, my
>keystrokes get saved, but it's a pain in the ass when doing real-time word
>processing (in Emacs) for example. What's going on? Why is it jumpy like
>that? The host machine is not busy, and I'm on a T1 line at work, so I can't
>believe it's network throughput or CPU time issues. Maybe I have some sort
>of parameter set wrong? Has anyone else observed this sort of intermittent

Do you have a firewall between client and server? It sounds like you do,
and that is has a state-table timeout of about 30s.

>2) If I open a connection, and don't touch it for some minutes, the host
>disconnects, leaving me with an unresponsive window - have to close it and
>re-connect. Is there any tweak that I can use to keep the connection alive?
>I don't own the host machine, so I wouldn't be able to muck with the ssh
>server on that side, but maybe there's some trick for making it stay

Put ServerAliveInterval into ssh_config on the client (OpenSSH 3.8 and
up) or ClientAliveInterval into sshd_config on the server (OpenSSH 2.9
and up). I suggest 20 seconds.

Also, run "ssh -vvv" and see if there are any messages corresponding with
your freezes.

Darren Tucker (dtucker at
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.

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