[Bug 1179344] Re: ssh doesn't get pty; says "inappropriate ioctl for device"

[Colin Watson]

Given that the nature of the other bug messes quite thoroughly with
sshd's ability to communicate between bits of itself, including the
protocol that allows it to set up a session properly, I don't think it's
fair to consider the TERM/pty/login-shell issues as unrelated.  If
1:6.2p1-3 fixes this then I would consider this bug a duplicate, even
though the exact set of symptoms reported here is a bit different.

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Title:
  ssh doesn't get pty; says "inappropriate ioctl for device"

Status in “openssh” package in Ubuntu:
  Confirmed

Bug description:
  ## Versions

      $ lsb_release -rd
      Description:    Ubuntu Saucy Salamander (development branch)
      Release:        13.10

      $ uname -a
      Linux emu 3.9.0-1-generic #5-Ubuntu SMP Wed May 8 20:52:16 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

      $ apt-show-versions -a openssh-server
      openssh-server 1:6.2p1-2 install ok installed
      openssh-server 1:6.2p1-2 saucy us.archive.ubuntu.com

  ## Problem

  After a recent (accidental) upgrade to 13.10, recent updates to the
  kernel seem to make inbound SSH connections problematic. Specifically,
  the remote client is unable to connect to a login shell. This was
  extremely difficult to diagnose, because all the client says is:

      $ ssh emu 
      Last login: Sun May 12 21:35:35 2013 from goldendelicious
      Shared connection to 192.168.1.127 closed.
      Connection to 192.168.1.127 closed by remote host.

  Even with the verbose flag turned on (e.g. `-v` and `-vvv`) all you
  see is that you connect, then get "debug1: Exit status -1" for no
  discernable reason. The rest of the verbose output is completely
  uninteresting However, there are other ways to debug this, as shown
  below.

  ### SSH connection results in dumb terminal

      $ echo $TERM
      xterm-256color

      $ ssh emu /bin/echo \$TERM
      dumb

  As you can see, openssh does not use the correct TERM environment
  variable. However, manually setting TERM (e.g. `export TERM=vt100`)
  doesn't solve the problem, because you don't actually have a pty. See
  next section.

  ### Non-login shells work...sort of

      $ ssh emu /bin/bash -i
      bash: cannot set terminal process group (-1): Inappropriate ioctl for device
      bash: no job control in this shell
      emu:~$  echo $TERM
      echodumb
       $TERM
      emu:~$ tty
      tty
      not a tty

  As you can see here, openssh is unable to open a tty or pty. If you
  try to force it with `-t` or `-tt`, then it returns to the previous
  behavior of simply closing the connection without explanation.

  ## Temporary Work-Around

  One way to work around this problem is to use X-Forwarding to launch
  an xterm as a login shell. For example:

      $ ssh emu xterm -e 'bash -l'

  This works, assigns a pty, and otherwise results in a usable remote
  connection, but is certainly not a substitute for having a working
  non-X11 shell.

  ## Expected Behavior

  1. OpenSSH should receive a pty on the remote host.
  2. The TERM variable should be properly propogated.
  3. There should be a more obvious way to debug this; openssh reports NOTHING of use in this situation, even with maximum verbosity.

  ProblemType: Bug
  DistroRelease: Ubuntu 13.10
  Package: openssh-server 1:6.2p1-2
  ProcVersionSignature: Ubuntu 3.9.0-1.5-generic 3.9.1
  Uname: Linux 3.9.0-1-generic x86_64
  NonfreeKernelModules: nvidia
  ApportVersion: 2.10-0ubuntu3
  Architecture: amd64
  Date: Sun May 12 21:40:41 2013
  EcryptfsInUse: Yes
  InstallationDate: Installed on 2011-10-15 (575 days ago)
  InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
  MarkForUpload: True
  SourcePackage: openssh
  UpgradeStatus: Upgraded to saucy on 2013-05-06 (6 days ago)

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