Bug#1136816: openssh-client: TCP connect hang in OpenSSH 10.0p2, nc works

On Sat, May 16, 2026 at 02:08:57PM +0200, Ezequiel Fernandez wrote:
>Package: openssh-client
>Version: 1:10.0p2-7
>Severity: normal

You quoted version 1:10.0p2-7, which is surprising as that's missing all 
the security updates we've released since trixie.  But the `ssh -V` 
output below suggests you in fact have version 1:10.0p2-7+deb13u2.

>OpenSSH 10.0p2 in Debian Trixie hangs indefinitely on TCP connect()
>to any remote host. nc(1) and curl(1) to the same IP:port work
>instantly, confirming this is not a network or firewall issue.
>
>Steps to reproduce:
>1. ssh -V  ->  OpenSSH_10.0p2 Debian-7+deb13u2, OpenSSL 3.5.5

It could still be a network problem, just a more subtle one involving 
quality-of-service settings.

Could you try upgrading to 1:10.0p1-7+deb13u4 from the recent stable 
point release, which applies several quality-of-service changes from 
more recent upstream releases?  It's quite possible that this will at 
least change the failure mode.  If it still doesn't work with that 
version, please include the full output of `ssh -vvvT [email protected]` 
until the point where you have to use Ctrl-C.

Please also include the output of `ssh -G [email protected]` so that we can 
see whether any local configuration might be affecting things.  (There 
shouldn't be anything secret in that output, but feel free to redact 
things you aren't comfortable with sharing as long as you make it clear 
you've done so.)

Thanks,