XAuthLocation $HOME/.Xauthority

It would not work with this entry in either file.

So I changed this entry in both files to:

XAuthLocation /usr/bin/xauth

And it works.

So for anyone that runs across this thread, I will put the config entries in both the files that are working now.

On the remote sshd_config file, I have:

X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost yes
AllowTcpForwarding yes
XAuthLocation /usr/bin/xauth

On the local system and its ssh_config file, I have in the  ~/.ssh/config  file:

Host IP_ADDR
    ForwardAgent yes
    ForwardX11 yes
    ForwardX11Trusted yes
    XAuthLocation /usr/bin/xauth 

To use, I open a terminal window and enter the Xephyr command to open a blank and black window:

Next, enter the command to ssh into the remote box and forward the xsession to display two on the local machine:

Lastly, in the same terminal window which is now showing connected to the remote machine, I entered

startxfce4

And it works.

ssh -X user@remote
Xephyr :1 -screen 1024x768 -resizeable &

And then one of the following:

icewm --display=:1
jwm -display=:1
DISPLAY=:1 openbox-session

usernames are not the same on local and remote machines.
I didn't have to do anything with Xauthority or Forwarding settings.

Tested on second machine where I had to use :2 instead of :1.

* Just to be perfectly clear, I was in a terminal and logged into the remote with 'ssh -X' when I ran startxfce4, and it affected the local machine instead of the remote.

This is an example of what I have used in the past:
https://nek0.eu/posts/2014-10-25-Deskto … ephyr.html
or
https://www.dedoimedo.com/computers/xephyr.html

But this depends on Xforwarding successfully working, which I am getting errors on at the moment.  Thanks again.

$ ssh -v -Y user@xxx.xxx.xxx.100

TL/DR-
- xauth is installed on both the client and server
- .Xauthority file is located on both client and server and it has the correct permissions
- sshd_config on server and ssh_config on client "appear" to have all needed options active.

These are the commands used with Xephyr,

This loads a blank black screen, which is normal.

user@host:~$ DISPLAY=:2 ssh -Y user@xxx.xxx.xxx.100

...
Warning: No xauth data; using fake authentication data for X11 forwarding.
...

Common configurations of client and server:

# xauth is installed on both the client and server

       
# xorg is installed on both client and server

# Xauthority has the proper permissions on both the client and server

I added this to both the server and client in the ~/.bashrc file just to try "something"

The username on the account is the same for both server and client.

Server setup

# sshd_config contains

# Client setup

# ssh_config contains in ~/.ssh/config

There is a lot written about this on the web and it seems rather straightforward to implement.  However, I am overlooking something.  I have tried several examples that I found on the web, but still I get these errors.

Additional info:
Even with the ssh x-forwarding errors, the ssh connection will succeed, so if I go ahead and issue the command to "startxfce4" in the terminal window connected to the server, I expect the xsession to start in the blank black Xephyr window.  Instead, I get this output:

But if I go into /etc/X11/Xwrapper-config and change

allowed_users=console

to

allowed_users=anybody

then the xsession will start, but not within the Xephyr nested x window.  It starts on the monitor connected to the physical machine. 

It is not forwarding the xsession to Xephyr, and I am out of ideas on what to check and I can not find anything new on the web to help me out, yet.  So I am asking for help.  Any ideas?