News Group Posts

sshd stty login

From: Bob Rasmussen <ras@anzio.com>
Subject: Re: sco-list: [OFF] OpenSSH on OpenServer 5.0.6a
Date: Tue, 30 Apr 2002 08:58:34 -0700
References: <NEBBLMPLNKHMEHJGNPIHIEEAEBAA.bill@mwdental.com> 

On Mon, 29 Apr 2002, Jean-Pierre Radley wrote:

> Bob Rasmussen propounded (on Mon, Apr 29, 2002 at 04:02:52PM -0700):
> | When sshd connects with SCO, it doesn't establish a good set of stty
> | parameters. If the ssh client doesn't send them, you end up in the state you
> | are in.
> |
> | AnzioWin handles this correctly, effective version 12.5m.
>
> Running ssh from OSR 5 to a Linux machine running sshd, or to another
> OSR 5 box running sshd, I've never seen any stty problems of this sort.
> Can you go into a bit more detail?

OK. After sshd validates the user, it must interact with the OS to get a shell
prompt. It may use the "login" program for this, I don't recall. Let's assume
it does. When it gets a connection through login, the user sees a shell
prompt, through a pseudo tty session.

In other Unix/Linux systems, the login program seems to hand to sshd a pty
with the stty settings already configured in a sane manner. Thus an <enter>
key, which sends a CR, gets converted to a LF (icrnl). Not so with OSR 5. It
seems to hand off a pty with stty set to "all zeros".

Part of both the ssh1 and ssh2 protocols allows the client to send stty
settings to the server. Some Windows clients do this, some do not. I'm not
sure about OpenSSH client on Unix, but from your comments I assume it does.

So:

OSR5 to Linux: Linux hands off a sane pty, no problem.

OSR5 to OSR5, or Linux to OSR5: Login hands off a bad pty, but the ssh client
sends the stty settings, so no problem.

Some Windows SSH client to OSR5: Login hands off a bad pty, the client doesn't
send stty settings, so things don't work well.

AnzioWin SSH client (current version) to OSR5: Client sends stty settings, all
is good.

Regards,
....Bob Rasmussen,   President,   Rasmussen Software, Inc.

personal e-mail: ras@anzio.com
 company e-mail: rsi@anzio.com
          voice: (US) 503-624-0360 (9:00-6:00 Pacific Time)
            fax: (US) 503-624-0760
            web: http://www.anzio.com

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