openssh unix dev - Oct 2025 - On the impossibility to use escape sequences when the networks hangs

On Mon, 13 Oct 2025, Dennis Clarke via openssh-unix-dev wrote:
> Seems to work fine at the beginning of a line. :/
This was improved relatively recently:

commit fec014785de198b9a325d1b94e324bb958c5fe7b
Author: djm at openbsd.org <djm at openbsd.org>
Date:   Wed Apr 20 04:19:11 2022 +0000

    upstream: Try to continue running local I/O for channels in state
    
    OPEN during SSH transport rekeying. The most visible benefit is that it
    should make ~-escapes work in the client (e.g. to exit) if the connection
    happened to have stalled during a rekey event. Based work by and ok dtucker@
    
    OpenBSD-Commit-ID: a66e8f254e92edd4ce09c9f750883ec8f1ea5f45

Before this change (in OpenSSH 9.1), an unresponsive connection might
get uninterruptibly stuck if it was in the process of rekeying but
AFAIK that should no longer be the case.

-d

Damien Miller wrote in
 <89d93aab-0510-31a4-9542-45a718702591 at mindrot.org>:
 |On Mon, 13 Oct 2025, Dennis Clarke via openssh-unix-dev wrote:
 |
 |> Seems to work fine at the beginning of a line. :/
 |
 |This was improved relatively recently:
 |
 |commit fec014785de198b9a325d1b94e324bb958c5fe7b
 |Author: djm at openbsd.org <djm at openbsd.org>
 |Date:   Wed Apr 20 04:19:11 2022 +0000
 |
 |    upstream: Try to continue running local I/O for channels in state
 |    
 |    OPEN during SSH transport rekeying. The most visible benefit is that it
 |    should make ~-escapes work in the client (e.g. to exit) if the \
 |    connection
 |    happened to have stalled during a rekey event. Based work by and \
 |    ok dtucker@
 |    
 |    OpenBSD-Commit-ID: a66e8f254e92edd4ce09c9f750883ec8f1ea5f45
 |
 |Before this change (in OpenSSH 9.1), an unresponsive connection might
 |get uninterruptibly stuck if it was in the process of rekeying but
 |AFAIK that should no longer be the case.

Should i open a bug for that ^Z, the ^C inconsistency, and i
do not know, it is a WireGuard VPN within which SSH is used,
and at times no packets get through whatsoever, then no input is
accepted at all, and ^C is not processed, too.

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)

Hey Damien.

On Tue, 2025-10-14 at 14:58 +1100, Damien Miller wrote:
> Before this change (in OpenSSH 9.1), an unresponsive connection might
> get uninterruptibly stuck if it was in the process of rekeying but
> AFAIK that should no longer be the case.
There probably are still some other cases left, see #2573.


Cheers,
Chris.