Re: sshd conflicts with mintty allocating /dev/tty[0-9]

[Christopher Faylor <cgf-use-the-mailinglist-please at cygwin dot com>]

On Mon, Aug 01, 2011 at 06:51:04PM +0300, Alexey Luchko wrote:
>Hi, everyone!
>
>
>I've run mkpasswd and mkgroups, installed sshd, run sshd-host-config, 
>turned on privilege separation, installed it as a service.
>
>'CYGWIN sshd' service starts normally but it closes connection right after 
>successful login:
>"""
>$ ssh localhost
>user@localhost's password:
>Connection to localhost closed by remote host.
>Connection to localhost closed.
>"""
>
>Logged in sshd's account and started '/usr/sbin/sshd -d' and tries to login 
>via ssh localhost.  Tail of sshd output follows:
>"""
>debug1: userauth-request for user user service ssh-connection method password
>debug1: attempt 2 failures 1
>Accepted password for user from ::1 port 63719 ssh2
>debug1: monitor_child_preauth: user has been authenticated by privileged 
>process
>debug1: Entering interactive session for SSH2.
>debug1: server_init_dispatch_20
>debug1: server_input_channel_open: ctype session rchan 0 win 1048576 max 16384
>debug1: input_session_request
>debug1: channel 0: new [server-session]
>debug1: session_new: session 0
>debug1: session_open: channel 0
>debug1: session_open: session 0: link with channel 0
>debug1: server_input_channel_open: confirm session
>debug1: server_input_global_request: rtype no-more-sessions@openssh.com 
>want_reply 0
>debug1: server_input_channel_req: channel 0 request pty-req reply 1
>debug1: session_by_channel: session 0 channel 0
>debug1: session_input_channel_req: session 0 req pty-req
>debug1: Allocating pty.
>debug1: session_pty_req: session 0 alloc /dev/tty2
>chown(/dev/tty2, 11135, 10513) failed: Bad file descriptor
>debug1: do_cleanup
>debug1: session_pty_cleanup: session 0 release /dev/tty2
>"""
>
>It conflicts with mintty because every mintty allocates terminal for 
>himself like this running in mintty:
>"""
>$ ls -l `tty`
>crw--w---- 1 user Domain Users 136, 0 Aug  1 18:46 /dev/tty0
>"""
>
>Version: CYGWIN_NT-6.1-WOW64 1.7.9(0.237/5/3) 2011-03-29 10:10 i686 Cygwin

I don't understand how this conflicts with mintty.  mintty should
allocate the first tty if it is the first thing run.  ssh would allocate
some other pty (tty2) after that.  I don't see anything amiss other than
the error message above.

We'll need to see the debugging details mentioned here:

http://cygwin.com/problems.html

Please provide information on any changes you've made to your ssh setup
as well as the cygcheck output mentioned there.

cgf

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