[Bug 2077576] Re: SSH client doesn't handle properly non-ASCII chars

[Sebastien Bacher]

** Changed in: openssh (Ubuntu Focal)
       Status: In Progress => Fix Committed

** Changed in: openssh (Ubuntu Jammy)
       Status: In Progress => Fix Committed

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https://bugs.launchpad.net/bugs/2077576

Title:
  SSH client doesn't handle properly non-ASCII chars

Status in openssh package in Ubuntu:
  Fix Released
Status in openssh source package in Focal:
  Fix Committed
Status in openssh source package in Jammy:
  Fix Committed
Status in openssh source package in Noble:
  Fix Released

Bug description:
  [ Impact ]

  Non-ascii visible chars are not properly rendered by clients, showing
  their octal visualization.

  Such as:

  Hello SSHD! We love \360\237\215\225!

  [ Test case ]

  ## Server preparation

  Enable PAM and keyboard interactive authentication in a ssh server:

  Add a configuration file such as:
   /etc/ssh/sshd_config.d/test-ssh-pam.conf

  Containing:

  UsePAM yes
  KbdInteractiveAuthentication yes

  Restart the server:

    sudo systemctl restart ssh.service

  Edit the sshd PAM configuration file, adding as first line:

    auth    requisite pam_echo.so Hello SSHD! We love 🍕!

  Can be done with the command:
    sudo sed '1 i\auth    requisite pam_echo.so Hello SSHD! We love 🍕!' -i /etc/pam.d/sshd

  ## Client test

  In the same host:

   ssh -o PubkeyAuthentication=no \
       -o PasswordAuthentication=no \
       -o PreferredAuthentications=keyboard-interactive \
       $USER at localhost

  The client should show:

  Hello SSHD-dev in devel schroot! Want some 🍕?
  ($USER at localhost) Password:

  Retry the same with another host and without keyboard authentication
  enabled in the server side.

  ## Cleanup

  Revert the changes done in the cleanup phase, after test is done

  sudo sed '/pam_echo\.so/d' -i /etc/pam.d/sshd
  sudo rm /etc/ssh/sshd_config.d/test-ssh-pam.conf

  [ Regression potential ]

  SSH info messages are not shown by the client.

  These kind of messages are normally shown only when PAM is enabled in
  the server side, so it should not affect the normal behavior.

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