Telnet Disconnects - Please help!

Mike Bird mgb-ubuntu at
Mon May 26 18:54:11 UTC 2008

On Mon May 26 2008 11:24:47 Harald Milz wrote:
> I am more than willing to provide all the information required to get this
> issue resolved. Just need to get it reproduced on a lab. I am sure I am not
> the first person that cannot reveal company IPs, and should I be, I ask for
> the patience to be able to reproduce this in a way so that I can send you
> guys the correct information. Not all of us have the experience you have
> with Linux and if this List is only for Pro's then I'll stop sending mails,
> but I understand this list is also meant for ppl like me who have some
> knowledge just not the enough experience to be able to resolve issues like
> the one I am having.

We're more than willing to help you ... when you can provide the information.

> You mention there is a way to reproduce network latency. But using a remote
> gateway as a route. I will try to find out if this is possible from outside
> our corporate LAN, within one of our DSL routers. I am even looking forward
> to setting up a DSL Router so that I can access it remotely without being
> on the corporate LAN. Just need some time.
> The problem is curiously only affecting ubuntu. No Windows XP-Vista-2003,
> Debian, Red Hat or CentOS we have running, either in a VM or native, are
> experiencing this issue. All in the same network segment (within the same
> Class C).

As a network engineer yourself, I'm sure you are aware that are
many TCP options.  It may well be, as Smoot has suggested, that
your Ubuntu box is the only one using Window Scaling.  Or it
could be something else.  Please let us know when you can release
complete pcaps to compare your Ubuntu and Debian sessions.

Given the huge number of people that use Linux for network
maintenance, I doubt you will find that modest network latency
alone is the cause of your problems.  Latency may however
exacerbate a problem elsewhere on your net, such as inappropriate
ICMP blocks, a host which cannot handle Window Scaling, or a
faulty telnet implementation (yes, they do exist).

--Mike Bird

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