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

[Treviño]

Public bug reported:

[ 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@localhost

The client should show:

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


## 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

** Affects: openssh (Ubuntu)
     Importance: Medium
     Assignee: Marco Trevisan (Treviño) (3v1n0)
         Status: Fix Released

** Affects: openssh (Ubuntu Focal)
     Importance: Medium
     Assignee: Marco Trevisan (Treviño) (3v1n0)
         Status: In Progress

** Affects: openssh (Ubuntu Jammy)
     Importance: Medium
     Assignee: Marco Trevisan (Treviño) (3v1n0)
         Status: In Progress

** Affects: openssh (Ubuntu Noble)
     Importance: Medium
     Assignee: Marco Trevisan (Treviño) (3v1n0)
         Status: Fix Released

** Also affects: openssh (Ubuntu Jammy)
   Importance: Undecided
       Status: New

** Changed in: openssh (Ubuntu Jammy)
   Importance: Undecided => Medium

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

** Changed in: openssh (Ubuntu Jammy)
     Assignee: (unassigned) => Marco Trevisan (Treviño) (3v1n0)

** Also affects: openssh (Ubuntu Focal)
   Importance: Undecided
       Status: New

** Changed in: openssh (Ubuntu Focal)
   Importance: Undecided => Medium

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

** Changed in: openssh (Ubuntu Focal)
     Assignee: (unassigned) => Marco Trevisan (Treviño) (3v1n0)

** Also affects: openssh (Ubuntu Noble)
   Importance: Undecided
       Status: New

** Changed in: openssh (Ubuntu Noble)
   Importance: Undecided => Medium

** Changed in: openssh (Ubuntu Noble)
       Status: New => In Progress

** Changed in: openssh (Ubuntu Noble)
     Assignee: (unassigned) => Marco Trevisan (Treviño) (3v1n0)

** Changed in: openssh (Ubuntu Noble)
       Status: In Progress => Fix Released

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

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

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

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