X-forwarding no longer works

[Robert Dinse]

I operate a Linux based Internet hosting service that includes Linux shell servers of various flavors. I control these from home using Ubuntu 21.10 presently. Until recently, X-forwarding has worked from all but ancient Redhat 6.2 servers. I recently upgraded my debian shell server to Bullet, and after the upgrade ssh -X debian.eskimo.com from my workstation nanook.eskimo.com ceased to function. It simply says "Cannot open DISPLAY". At the time, all the others continued to work. Today, when I went to do upgrades, now ssh -X is forwarding across the board to all flavors of Linux. I did an ssh -V, nothing obvious wrong in the connection.

debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering public key: /home/nanook/.ssh/id_rsa RSA SHA256:a5bReJXl7L91eGOuCYugHsY2rn2a0WTDXEBTC93YdmA agent
debug1: Server accepts key: /home/nanook/.ssh/id_rsa RSA SHA256:a5bReJXl7L91eGOuCYugHsY2rn2a0WTDXEBTC93YdmA agent
debug1: Authentication succeeded (publickey).
Authenticated to igloo.eskimo.com ([204.122.16.128]:22).
debug1: channel 0: new [client-session]
debug1: Requesting <email address hidden>
debug1: Entering interactive session.
debug1: pledge: network
debug1: client_input_global_request: rtype <email address hidden> want_reply 0
debug1: Remote: /home/nanook/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
debug1: Remote: /home/nanook/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: client_input_channel_req: channel 0 rtype <email address hidden> reply 0
debug1: channel 0: free: client-session, nchannels 1
debug1: fd 2 clearing O_NONBLOCK
Connection to igloo.eskimo.com closed.
Transferred: sent 3748, received 3820 bytes, in 6.4 seconds
Bytes per second: sent 589.4, received 600.8

I don't see anything obviously wrong here but still it does not work, I get:
xclock
Error: Can't open display:

ProblemType: Bug
DistroRelease: Ubuntu 21.10
Package: ssh (not installed)
Uname: Linux 5.13.19 x86_64
ApportVersion: 2.20.11-0ubuntu71
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: MATE
Date: Tue Nov 2 17:31:14 2021
SourcePackage: openssh
UpgradeStatus: No upgrade log present (probably fresh install)

[Paride Legovini (paride)]

Hello Robert and thanks for your bug report. You wrote:

> I recently upgraded my debian shell server to Bullet

but I'm not sure I get what you mean. Is it a Debian system or an Ubuntu system? If it's upgrading a Debian system that broke your setup then there's nothing I can see that points to a bug in Ubuntu. Moreover: what is Bullet? Did you mean Bullseye or Bookworm?

If you think there's actually a bug in Ubuntu here please share more of your reasoning, possibly providing a reproducer, e.g. by ssh -X to a container or VM. I'm marking this bug report as Incomplete for the moment. Feel free to change it back to New after commenting back. Thanks!

[Robert Dinse (nanook)]

      I am originating from a Ubuntu 21.10 system to a Debian Bullet system,
but now I can't get X-forwarding to work from any site I connect to when
originating from Ubuntu 21.10.

-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
  Eskimo North Linux Friendly Internet Access, Shell Accounts, and Hosting.
    Knowledgeable human assistance, not telephone trees or script readers.
  See our web site: http://www.eskimo.com/ [phone] or [phone].

On Mon, 8 Nov 2021, Paride Legovini wrote:

> Date: Mon, 08 Nov 2021 15:43:10 -0000
> From: Paride Legovini <email address hidden>
> To: <email address hidden>
> Subject: [Bug 1949535] Re: X-forwarding no longer works
>
> Hello Robert and thanks for your bug report. You wrote:
>
>> I recently upgraded my debian shell server to Bullet
>
> but I'm not sure I get what you mean. Is it a Debian system or an Ubuntu
> system? If it's upgrading a Debian system that broke your setup then
> there's nothing I can see that points to a bug in Ubuntu. Moreover: what
> is Bullet? Did you mean Bullseye or Bookworm?
>
> If you think there's actually a bug in Ubuntu here please share more of
> your reasoning, possibly providing a reproducer, e.g. by ssh -X to a
> container or VM. I'm marking this bug report as Incomplete for the
> moment. Feel free to change it back to New after commenting back.
> Thanks!
>
> ** Changed in: openssh (Ubuntu)
> Status: New => Incomplete
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1949535
>
> Title:
> X-forwarding no longer works
>
> Status in openssh package in Ubuntu:
> Incomplete
>
> Bug description:
> I operate a Linux based Internet hosting service that includes Linux
> shell servers of various flavors. I control these from home using
> Ubuntu 21.10 presently. Until recently, X-forwarding has worked from
> all but ancient Redhat 6.2 servers. I recently upgraded my debian
> shell server to Bullet, and after the upgrade ssh -X debian.eskimo.com
> from my workstation nanook.eskimo.com ceased to function. It simply
> says "Cannot open DISPLAY". At the time, all the others continued to
> work. Today, when I went to do upgrades, now ssh -X is forwarding
> across the board to all flavors of Linux. I did an ssh -V, nothing
> obvious wrong in the connection.
>
> debug1: Authentications that can continue: publickey,password
> debug1: Next authentication method: publickey
> debug1: Offering public key: /home/nanook/.ssh/id_rsa RSA SHA256:a5bReJXl7L91eGOuCYugHsY2rn2a0WTDXEBTC93YdmA agent
> debug1: Server accepts key: /home/nanook/.ssh/id_rsa RSA SHA256:a5bReJXl7L91eGOuCYugHsY2rn2a0WTDXEBTC93YdmA agent
> debug1: Authentication succeeded (publickey).
> Authenticated to igloo.eskimo.com ([204.122.16.128]:22).
> debug1: channel 0: new [client-session]
> debug1: Requesting <email address hidden>
> debug1: Entering interactive session.
> debug1: pledge: network
> debug1: client_input_global_request: rtype <email address hidden> want_reply 0
> debug1: Remote: /home/nanook/.ssh/authorized_keys:1: key options: agent-forwarding port-forw...

[Lucas Kanashiro (lucaskanashiro)]

This is confusing Robert, is your target system running Debian Bullseye? There is no Debian release called Bullet. Do you have any custom configuration in the server or client side? Please provide more information, for instance detailed steps, so we can attempt to reproduce it.

[Robert Dinse (nanook)]

      Yes Bullseye, you can close this ticket. Something went wrong during
the upgrade. I re-installed it now it is working.

-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-
  Eskimo North Linux Friendly Internet Access, Shell Accounts, and Hosting.
    Knowledgeable human assistance, not telephone trees or script readers.
  See our web site: http://www.eskimo.com/ [phone] or [phone].

On Tue, 9 Nov 2021, Lucas Kanashiro wrote:

> Date: Tue, 09 Nov 2021 15:08:27 -0000
> From: Lucas Kanashiro <email address hidden>
> To: <email address hidden>
> Subject: [Bug 1949535] Re: X-forwarding no longer works
>
> This is confusing Robert, is your target system running Debian Bullseye?
> There is no Debian release called Bullet. Do you have any custom
> configuration in the server or client side? Please provide more
> information, for instance detailed steps, so we can attempt to reproduce
> it.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1949535
>
> Title:
> X-forwarding no longer works
>
> Status in openssh package in Ubuntu:
> Incomplete
>
> Bug description:
> I operate a Linux based Internet hosting service that includes Linux
> shell servers of various flavors. I control these from home using
> Ubuntu 21.10 presently. Until recently, X-forwarding has worked from
> all but ancient Redhat 6.2 servers. I recently upgraded my debian
> shell server to Bullet, and after the upgrade ssh -X debian.eskimo.com
> from my workstation nanook.eskimo.com ceased to function. It simply
> says "Cannot open DISPLAY". At the time, all the others continued to
> work. Today, when I went to do upgrades, now ssh -X is forwarding
> across the board to all flavors of Linux. I did an ssh -V, nothing
> obvious wrong in the connection.
>
> debug1: Authentications that can continue: publickey,password
> debug1: Next authentication method: publickey
> debug1: Offering public key: /home/nanook/.ssh/id_rsa RSA SHA256:a5bReJXl7L91eGOuCYugHsY2rn2a0WTDXEBTC93YdmA agent
> debug1: Server accepts key: /home/nanook/.ssh/id_rsa RSA SHA256:a5bReJXl7L91eGOuCYugHsY2rn2a0WTDXEBTC93YdmA agent
> debug1: Authentication succeeded (publickey).
> Authenticated to igloo.eskimo.com ([204.122.16.128]:22).
> debug1: channel 0: new [client-session]
> debug1: Requesting <email address hidden>
> debug1: Entering interactive session.
> debug1: pledge: network
> debug1: client_input_global_request: rtype <email address hidden> want_reply 0
> debug1: Remote: /home/nanook/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
> debug1: Remote: /home/nanook/.ssh/authorized_keys:1: key options: agent-forwarding port-forwarding pty user-rc x11-forwarding
> debug1: Sending environment.
> debug1: Sending env LANG = en_US.UTF-8
> debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
> debug1: client_input_channel_req: channel 0 rtype <email address hidden> reply 0
> debug1: channel 0: free: client-session, nchannels 1
> debug1: fd 2 clearing O_NONBLOCK
> Connection to igloo.eskimo.com clo...

[Sergio Durigan Junior (sergiodj)]

Closing the bug as Invalid as per the reporter's request.