Delays in ssh connections between two local Linux computers

[shimi]

On Mon, Sep 12, 2011 at 4:37 PM, Shlomi Fish <shlomif at gmail.com> wrote:

> Hi all,
>
> (I apologise from writing from my gmail.com account, but as you'll see
> below,
> writing from my home E-mail account is not bearable.).
>
> I have a desktop x86-64 Core i3 machine (running Mageia Linux 1) that
> connects
> via wired Ethernet to my NAT/router and there is a remote x86-64 Core Duo
> laptop (running Mageia Linux 2), connected via wireless. Often when I type
> commands on bash on the remote laptop via ssh, there is a significant
> delay,
> and moreover running claws-mail or gringotts (two fast gtk+ apps) from the
> laptop are slow, which hadn't been the case with my older desktop machine.
> tcpdump -i wlan0 on the laptop and htop on the laptop show nothing that
> might
> cause it.
>
> The delays in the connectivity were not bad with the previous desktop
> machine
> which was an old Pentium 4 2.4GHz machine, which was much slower and
> underpowered.
>
> So far I tried:
>
> 1. Doing /etc/init.d/iptables stop on the desktop machine.
>
> 2. Relocating the laptop closer to the wifi NAT/router.
>
> Neither of those helped.
>
> Can anyone shed any light on this?
>
>
Everyone on this thread so far mostly replied with regards to SSH session
_setup_ time - from some reason - when I read your original post, I
understood that what you are actually complaining about is high latency on
an _already active_ SSH session.

If I understood you correctly, then the first thing to look at is simply...
pings to the other side, to see how much actual network latency and/or drops
you have.

If I understood you incorrectly (and everybody else understood you
correctly), then I would add to everyone's suggestions, this: take a look to
see if you have avahi-daemon running. This little creature have a tendency
to cause session setup delays, even with all DNS off... if you do have it,
take it off if it's not needed (and it probably isn't...)

HTH,

-- Shimi
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