News Group Posts

long delay connecting with ssh

From: Bela Lubkin <belal@sco.com>
Subject: Re: Openssh Slow on 5.07
Date: Fri, 18 Jul 2003 22:57:44 GMT
References: <bJhRa.7892$r35.1703@fe03.atl2.webusenet.com>
<HI8r1L.3E6@stevedunn.ca> 

Stephen M. Dunn wrote:

> In article <bJhRa.7892$r35.1703@fe03.atl2.webusenet.com> "willjay" <willjay@excite.com> writes:
> $I just installed 5.07 on a Compaq Pentium Pro Quad 200mz Proliant.  Openssh
> $is very slow to login and screen updates freeze for periods of 4 - 5
> $seconds.
> 
>    I have a client who recently upgraded from an older machine
> (5.0.5, PIII 700 or thereabouts, openssh 3.3 or 3.4) to a new
> single-processor Xeon 2.4 GHz with a gig of RAM and 5.0.7.
> When I say upgraded, it was done as a fresh install on the new
> box, and then I manually imported users via ap, moved files,
> updated config files, etc. so I'm confident that I didn't whack
> part of the new OS or openssh with old stuff.
> 
>    Both the client and server parts of openssh are slower on this
> machine than on the older machine.  Connecting to a remote machine
> via ssh results in a 15-30 second (haven't actually timed it)
> delay after providing the user name and password, before the
> next thing shows up (the TERM= line from the .profile).  Connecting
> to the new machine from a remote machine is somewhat slower; there's
> a delay of a few seconds (maybe 5 or so - again, haven't timed it)
> after providing either a user name and password or user name and
> the password for a private keyfile.
> 
>    It's not a big deal for me since I rarely need to ssh from that
> box to another and I can deal with a 5-second delay when I connect
> in from elsewhere.  One of these days I may try turning on debugging
> to see if I can figure out at what point it's bogging down.
> 
>    In both cases, I haven't noticed anything unusual once the
> login has completed - screen updates etc. seem to work just as
> well as they did on the older box.

Stephen, your case sounds like a DNS problem.  If your DNS was
completely failing, you would see 60-second pauses.  Short pauses smell
like you have two "nameserver" lines in /etc/resolv.conf, and the first
one points to an IP address that isn't there at all.  If it pointed to a
live machine that wasn't serving DNS, queries would get an immediate
negative response and the querant would immediately move on to the 2nd
server.  If there's no machine at the IP address (or it's behind a
firewall that doesn't transmit ICMP error packets), you'll get a 5-10
second timeout before the querant moves on to the next choice.

I have no idea about the original poster's pauses.  He should do some
basic performance analysis -- check for maxed-out CPU, that sort of
thing.

>Bela<

Comments?

Jump to Comments

Many of the products and books I review are things I purchased for my own use. Some were given to me specifically for the purpose of reviewing them. I resell or can earn commissions from the sale of some of these items. Links within these pages may be affiliate links that pay me for referring you to them. That's mostly insignificant amounts of money; whenever it is not I have made my relationship plain. I also may own stock in companies mentioned here. If you have any question, please do feel free to contact me.

Specific links that take you to pages that allow you to purchase the item I reviewed are very likely to pay me a commission. Many of the books I review were given to me by the publishers specifically for the purpose of writing a review. These gifts and referral fees do not affect my opinions; I often give bad reviews anyway.

We use Google third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, click here.