sshd not working properly

Corinna Vinschen corinna-cygwin@cygwin.com
Fri Jan 17 14:00:49 GMT 2025


On Jan 17 06:41, Brian Inglis via Cygwin wrote:
> On 2025-01-17 05:51, Corinna Vinschen via Cygwin wrote:
> > On Jan 17 11:59, Mario Emmenlauer via Cygwin wrote:
> > > I am under the impression that there may be a misbehavior in more recent
> > > Cygwin OpenSSH :-(
> > > 
> > > I observe the same problem as Andy Wood was having, and found another
> > > very recent identical report at https://serverfault.com/q/1168457/473559.
> > > Their cases, as well as mine, seem to share, that OpenSSH can no longer
> > > correctly authenticate as a user without having the plain text password
> > > stored in the registry.
> > > 
> > > In my case, this is exclusively limited to domain users. Local users
> > > work correctly. I can see that at least one other report, the one at
> > > Serverfault, is also for a domain user. Also, everything that is
> > > reported at Serverfault applies basically identically to my case, i.e.
> > > the connection being just dropped, and the only relevant message from
> > > OpenSSH being "fatal: seteuid 4096: Function not implemented".
> > 
> > I just tested this on my local W11 24H2 Enterprise installation with
> > Cygwin 3.5.5 and OpenSSH 9.9p1 installed as service under the SYSTEM
> > account, and it works fine for me in a Windows domain with one 2019 and
> > one 2022 Domain Server.
> > 
> > I tested with a user account in the administrators group as well as with
> > a non-admin user account, and to both accounts I can login with pubkey
> > authentication as expected.
> > 
> > The error message "seteuid 4096: Function not implemented" is weird.
> > The internal implementation only uses documented functions.
> > 
> > Which Windows version are you running the service on exactly?
> > 
> > Do you have any other entries in the server-side Windows Log, which may
> > be connected, especially inside the Security log.  Kerberos or so.
> > 
> > Other than that, it might be prudent to run sshd in a SYSTEM shell
> > under strace.
> 
> Any chance the user is also running Windows sshd and tyhat has grabbed the port?

Good point, worth checking...


Corinna


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